Migrate tests to JUnit5 (core / hudson / 2) (#10577)

core/src/test/java/hudson/BulkChangeTest.java

@@ -24,18 +24,18 @@
 
 package hudson;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import hudson.model.Saveable;
 import java.io.IOException;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * Tests {@link BulkChange}.
  *
  * @author Kohsuke Kawaguchi
  */
-public class BulkChangeTest {
+class BulkChangeTest {
 
     private static class Point implements Saveable {
         /**
@@ -72,7 +72,7 @@ public class BulkChangeTest {
      * If there is no BulkChange, we should see two saves.
      */
     @Test
-    public void noBulkChange() throws Exception {
+    void noBulkChange() throws Exception {
         Point pt = new Point();
         pt.set(0, 0);
         assertEquals(2, pt.saveCount);
@@ -82,7 +82,7 @@ public class BulkChangeTest {
      * With a {@link BulkChange}, this will become just one save.
      */
     @Test
-    public void bulkChange() throws Exception {
+    void bulkChange() throws Exception {
         Point pt = new Point();
         BulkChange bc = new BulkChange(pt);
         try {
@@ -97,7 +97,7 @@ public class BulkChangeTest {
      * {@link BulkChange}s can be nested.
      */
     @Test
-    public void nestedBulkChange() throws Exception {
+    void nestedBulkChange() throws Exception {
         Point pt = new Point();
         Point pt2 = new Point();
         BulkChange bc1 = new BulkChange(pt);

core/src/test/java/hudson/ChannelRule.java

@@ -1,64 +0,0 @@
-package hudson;
-
-
-import hudson.remoting.Channel;
-import hudson.remoting.ChannelBuilder;
-import hudson.remoting.FastPipedInputStream;
-import hudson.remoting.FastPipedOutputStream;
-import java.io.IOException;
-import java.io.UncheckedIOException;
-import java.util.concurrent.Callable;
-import java.util.concurrent.ExecutorService;
-import java.util.concurrent.Executors;
-import java.util.concurrent.Future;
-import org.junit.rules.ExternalResource;
-
-/**
- * Test that uses a connected channel.
- *
- * @author Kohsuke Kawaguchi
- */
-public final class ChannelRule extends ExternalResource {
-    /**
-     * Two channels that are connected to each other, but shares the same classloader.
-     */
-    public Channel french;
-    public Channel british;
-    private ExecutorService executors;
-
-    @Override protected void before() throws Exception {
-        executors = Executors.newCachedThreadPool();
-        final FastPipedInputStream p1i = new FastPipedInputStream();
-        final FastPipedInputStream p2i = new FastPipedInputStream();
-        final FastPipedOutputStream p1o = new FastPipedOutputStream(p1i);
-        final FastPipedOutputStream p2o = new FastPipedOutputStream(p2i);
-
-        Future<Channel> f1 = executors.submit(new Callable<>() {
-            @Override
-            public Channel call() throws Exception {
-                return new ChannelBuilder("This side of the channel", executors).withMode(Channel.Mode.BINARY).build(p1i, p2o);
-            }
-        });
-        Future<Channel> f2 = executors.submit(new Callable<>() {
-            @Override
-            public Channel call() throws Exception {
-                return new ChannelBuilder("The other side of the channel", executors).withMode(Channel.Mode.BINARY).build(p2i, p1o);
-            }
-        });
-        french = f1.get();
-        british = f2.get();
-    }
-
-    @Override protected void after() {
-        try {
-            french.close(); // this will automatically initiate the close on the other channel, too.
-            french.join();
-            british.join();
-        } catch (IOException e) {
-            throw new UncheckedIOException(e);
-        } catch (InterruptedException x) {
-            throw new AssertionError(x);
-        }
-        executors.shutdownNow();
-    }
-}

core/src/test/java/hudson/ClassicPluginStrategyTest.java

@@ -37,10 +37,10 @@ import org.junit.jupiter.api.Test;
 /**
  * @author <a href="mailto:tom.fennelly@gmail.com">tom.fennelly@gmail.com</a>
  */
-public class ClassicPluginStrategyTest {
+class ClassicPluginStrategyTest {
 
     @Test
-    public void test_getDetachedPlugins() {
+    void test_getDetachedPlugins() {
         List<DetachedPlugin> list = DetachedPluginsUtil.getDetachedPlugins(new VersionNumber("1.296"));
 
         assertTrue(list.size() >= 14); // There were 14 at the time of writing this test

core/src/test/java/hudson/EnvVarsTest.java

@@ -41,17 +41,17 @@ import org.junit.jupiter.api.Test;
 /**
  * @author Kohsuke Kawaguchi
  */
-public class EnvVarsTest {
+class EnvVarsTest {
 
     @Test
-    public void caseInsensitive() {
+    void caseInsensitive() {
         EnvVars ev = new EnvVars(Map.of("Path", "A:B:C"));
         assertTrue(ev.containsKey("PATH"));
         assertEquals("A:B:C", ev.get("PATH"));
     }
 
     @Test
-    public void overrideExpandingAll() {
+    void overrideExpandingAll() {
         EnvVars env = new EnvVars();
         env.put("PATH", "orig");
         env.put("A", "Value1");
@@ -71,7 +71,7 @@ public class EnvVarsTest {
     }
 
     @Test
-    public void overrideOrderCalculatorSimple() {
+    void overrideOrderCalculatorSimple() {
         EnvVars env = new EnvVars();
         EnvVars overrides = new EnvVars();
         overrides.put("A", "NoReference");
@@ -87,7 +87,7 @@ public class EnvVarsTest {
     }
 
     @Test
-    public void overrideOrderCalculatorInOrder() {
+    void overrideOrderCalculatorInOrder() {
         EnvVars env = new EnvVars();
         EnvVars overrides = new EnvVars();
         overrides.put("A", "NoReference");
@@ -102,7 +102,7 @@ public class EnvVarsTest {
     }
 
     @Test
-    public void overrideOrderCalculatorMultiple() {
+    void overrideOrderCalculatorMultiple() {
         EnvVars env = new EnvVars();
         EnvVars overrides = new EnvVars();
         overrides.put("A", "Noreference");
@@ -115,7 +115,7 @@ public class EnvVarsTest {
     }
 
     @Test
-    public void overrideOrderCalculatorSelfReference() {
+    void overrideOrderCalculatorSelfReference() {
         EnvVars env = new EnvVars();
         EnvVars overrides = new EnvVars();
         overrides.put("PATH", "some;${PATH}");
@@ -126,7 +126,7 @@ public class EnvVarsTest {
     }
 
     @Test
-    public void overrideOrderCalculatorCyclic() {
+    void overrideOrderCalculatorCyclic() {
         EnvVars env = new EnvVars();
         env.put("C", "Existing");
         EnvVars overrides = new EnvVars();
@@ -144,7 +144,7 @@ public class EnvVarsTest {
     }
 
     @Test
-    public void putIfNotNull() {
+    void putIfNotNull() {
         EnvVars env = new EnvVars();
         env.putIfNotNull("foo", null);
         assertTrue(env.isEmpty());
@@ -153,7 +153,7 @@ public class EnvVarsTest {
     }
 
     @Test
-    public void putAllNonNull() {
+    void putAllNonNull() {
         EnvVars env = new EnvVars();
         TreeMap<String, String> map = new TreeMap<>();
         map.put("A", "a");

core/src/test/java/hudson/FilePathTest.java

@@ -26,14 +26,14 @@ package hudson;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assume.assumeFalse;
-import static org.junit.Assume.assumeTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assumptions.assumeFalse;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.verify;
 import static org.mockito.Mockito.when;
@@ -41,6 +41,10 @@ import static org.mockito.Mockito.when;
 import hudson.FilePath.TarCompression;
 import hudson.model.TaskListener;
 import hudson.os.WindowsUtil;
+import hudson.remoting.Channel;
+import hudson.remoting.ChannelBuilder;
+import hudson.remoting.FastPipedInputStream;
+import hudson.remoting.FastPipedOutputStream;
 import hudson.remoting.VirtualChannel;
 import hudson.slaves.WorkspaceList;
 import hudson.util.StreamTaskListener;
@@ -51,6 +55,7 @@ import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.RandomAccessFile;
+import java.io.UncheckedIOException;
 import java.net.ConnectException;
 import java.net.HttpURLConnection;
 import java.net.URL;
@@ -79,29 +84,66 @@ import java.util.zip.ZipOutputStream;
 import org.apache.commons.io.FileUtils;
 import org.apache.tools.ant.Project;
 import org.apache.tools.ant.taskdefs.Chmod;
-import org.junit.Ignore;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.jvnet.hudson.test.Issue;
 import org.mockito.Mockito;
 
 /**
  * @author Kohsuke Kawaguchi
  */
-public class FilePathTest {
+class FilePathTest {
 
-    @Rule public ChannelRule channels = new ChannelRule();
-    @Rule public TemporaryFolder temp = new TemporaryFolder();
+    @TempDir
+    private File temp;
 
-    @Test public void copyTo() throws Exception {
-        File tmp = temp.newFile();
-        FilePath f = new FilePath(channels.french, tmp.getPath());
+    /**
+     * Two channels that are connected to each other, but shares the same classloader.
+     */
+    private Channel french;
+    private Channel british;
+    private ExecutorService executors;
+
+    @BeforeEach
+    void setUp() throws Exception {
+        executors = Executors.newCachedThreadPool();
+        final FastPipedInputStream p1i = new FastPipedInputStream();
+        final FastPipedInputStream p2i = new FastPipedInputStream();
+        final FastPipedOutputStream p1o = new FastPipedOutputStream(p1i);
+        final FastPipedOutputStream p2o = new FastPipedOutputStream(p2i);
+
+        Future<Channel> f1 = executors.submit(() -> new ChannelBuilder("This side of the channel", executors).withMode(Channel.Mode.BINARY).build(p1i, p2o));
+        Future<Channel> f2 = executors.submit(() -> new ChannelBuilder("The other side of the channel", executors).withMode(Channel.Mode.BINARY).build(p2i, p1o));
+        french = f1.get();
+        british = f2.get();
+    }
+
+    @AfterEach
+    void tearDown() {
+        try {
+            french.close(); // this will automatically initiate the close on the other channel, too.
+            french.join();
+            british.join();
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        } catch (InterruptedException x) {
+            throw new AssertionError(x);
+        }
+        executors.shutdownNow();
+    }
+
+    @Test
+    void copyTo() throws Exception {
+        File tmp = File.createTempFile("junit", null, temp);
+        FilePath f = new FilePath(french, tmp.getPath());
         try (OutputStream out = OutputStream.nullOutputStream()) {
             f.copyTo(out);
         }
-        assertTrue("target does not exist", tmp.exists());
-        assertTrue("could not delete target " + tmp.getPath(), tmp.delete());
+        assertTrue(tmp.exists(), "target does not exist");
+        assertTrue(tmp.delete(), "could not delete target " + tmp.getPath());
     }
 
     /**
@@ -110,12 +152,13 @@ public class FilePathTest {
      */
     // TODO: this test is much too slow to be a traditional unit test. Should be extracted into some stress test
     // which is no part of the default test harness?
-    @Test public void noFileLeakInCopyTo() throws Exception {
+    @Test
+    void noFileLeakInCopyTo() throws Exception {
         for (int j = 0; j < 2500; j++) {
-            File tmp = temp.newFile();
+            File tmp = File.createTempFile("junit", null, temp);
             FilePath f = new FilePath(tmp);
-            File tmp2 = temp.newFile();
-            FilePath f2 = new FilePath(channels.british, tmp2.getPath());
+            File tmp2 = File.createTempFile("junit", null, temp);
+            FilePath f2 = new FilePath(british, tmp2.getPath());
 
             f.copyTo(f2);
 
@@ -137,8 +180,9 @@ public class FilePathTest {
      * Also see JENKINS-7897
      */
     @Issue("JENKINS-7871")
-    @Test public void noRaceConditionInCopyTo() throws Exception {
-        final File tmp = temp.newFile();
+    @Test
+    void noRaceConditionInCopyTo() throws Exception {
+        final File tmp = File.createTempFile("junit", null, temp);
 
            int fileSize = 90000;
 
@@ -197,7 +241,7 @@ public class FilePathTest {
                     }
                 }
 
-                FilePath f = new FilePath(channels.french, file.getPath());
+                FilePath f = new FilePath(french, file.getPath());
                 Sink sink = new Sink();
                 f.copyTo(sink);
                 return sink.count.get();
@@ -212,11 +256,12 @@ public class FilePathTest {
         }
     }
 
-    @Test public void repeatCopyRecursiveTo() throws Exception {
+    @Test
+    void repeatCopyRecursiveTo() throws Exception {
         // local->local copy used to return 0 if all files were "up to date"
         // should return number of files processed, whether or not they were copied or already current
-        File src = temp.newFolder("src");
-        File dst = temp.newFolder("dst");
+        File src = newFolder(temp, "src");
+        File dst = newFolder(temp, "dst");
             File.createTempFile("foo", ".tmp", src);
             FilePath fp = new FilePath(src);
             assertEquals(1, fp.copyRecursiveTo(new FilePath(dst)));
@@ -225,11 +270,12 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-9540")
-    @Test public void errorMessageInRemoteCopyRecursive() throws Exception {
-        File src = temp.newFolder("src");
-        File dst = temp.newFolder("dst");
+    @Test
+    void errorMessageInRemoteCopyRecursive() throws Exception {
+        File src = newFolder(temp, "src");
+        File dst = newFolder(temp, "dst");
             FilePath from = new FilePath(src);
-            FilePath to = new FilePath(channels.british, dst.getAbsolutePath());
+            FilePath to = new FilePath(british, dst.getAbsolutePath());
             for (int i = 0; i < 10000; i++) {
                 // TODO is there a simpler way to force the TarOutputStream to be flushed and the reader to start?
                 // Have not found a way to make the failure guaranteed.
@@ -257,8 +303,9 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-4039")
-    @Test public void archiveBug() throws Exception {
-            FilePath d = new FilePath(channels.french, temp.getRoot().getPath());
+    @Test
+    void archiveBug() throws Exception {
+            FilePath d = new FilePath(french, temp.getPath());
             d.child("test").touch(0);
             try (OutputStream out = OutputStream.nullOutputStream()) {
                 d.zip(out);
@@ -268,7 +315,8 @@ public class FilePathTest {
             }
     }
 
-    @Test public void normalization() {
+    @Test
+    void normalization() {
         compare("abc/def\\ghi", "abc/def\\ghi"); // allow mixed separators
 
         { // basic '.' trimming
@@ -322,7 +370,8 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-6494")
-    @Test public void getParent() {
+    @Test
+    void getParent() {
         FilePath fp = new FilePath((VirtualChannel) null, "/abc/def");
         assertEquals("/abc", (fp = fp.getParent()).getRemote());
         assertEquals("/", (fp = fp.getParent()).getRemote());
@@ -352,7 +401,8 @@ public class FilePathTest {
      * Performs round-trip archiving for Tar handling methods.
      * @throws Exception test failure
      */
-    @Test public void compressTarUntarRoundTrip() throws Exception {
+    @Test
+    void compressTarUntarRoundTrip() throws Exception {
         checkTarUntarRoundTrip("compressTarUntarRoundTrip_zero", 0);
         checkTarUntarRoundTrip("compressTarUntarRoundTrip_small", 100);
         checkTarUntarRoundTrip("compressTarUntarRoundTrip_medium", 50000);
@@ -365,15 +415,16 @@ public class FilePathTest {
      * @throws Exception test failure
      */
     @Issue("JENKINS-10629")
-    @Ignore
-    @Test public void archiveBigFile() throws Exception {
+    @Disabled
+    @Test
+    void archiveBigFile() throws Exception {
         final long largeFileSize = 9000000000L; // >8589934591 bytes
         final String filePrefix = "JENKINS-10629";
         checkTarUntarRoundTrip(filePrefix, largeFileSize);
     }
 
     private void checkTarUntarRoundTrip(String filePrefix, long fileSize) throws Exception {
-        final File tmpDir = temp.newFolder(filePrefix);
+        final File tmpDir = newFolder(temp, filePrefix);
         final File tempFile =  new File(tmpDir, filePrefix + ".log");
         RandomAccessFile file = new RandomAccessFile(tempFile, "rw");
         final File tarFile = new File(tmpDir, filePrefix + ".tar");
@@ -385,18 +436,18 @@ public class FilePathTest {
         // Compress archive
         final FilePath tmpDirPath = new FilePath(tmpDir);
         int tar = tmpDirPath.tar(Files.newOutputStream(tarFile.toPath()), tempFile.getName());
-        assertEquals("One file should have been compressed", 1, tar);
+        assertEquals(1, tar, "One file should have been compressed");
 
         // Decompress
-        FilePath outDir = new FilePath(temp.newFolder(filePrefix + "_out"));
+        FilePath outDir = new FilePath(newFolder(temp, filePrefix + "_out"));
         final FilePath outFile = outDir.child(tempFile.getName());
         tmpDirPath.child(tarFile.getName()).untar(outDir, TarCompression.NONE);
-        assertEquals("Result file after the roundtrip differs from the initial file",
-                new FilePath(tempFile).digest(), outFile.digest());
+        assertEquals(new FilePath(tempFile).digest(), outFile.digest(), "Result file after the roundtrip differs from the initial file");
     }
 
-    @Test public void list() throws Exception {
-        File baseDir = temp.getRoot();
+    @Test
+    void list() throws Exception {
+        File baseDir = temp;
             final Set<FilePath> expected = new HashSet<>();
             expected.add(createFilePath(baseDir, "top", "sub", "app.log"));
             expected.add(createFilePath(baseDir, "top", "sub", "trace.log"));
@@ -406,8 +457,9 @@ public class FilePathTest {
             assertEquals(expected, new HashSet<>(Arrays.asList(result)));
     }
 
-    @Test public void listWithExcludes() throws Exception {
-        File baseDir = temp.getRoot();
+    @Test
+    void listWithExcludes() throws Exception {
+        File baseDir = temp;
             final Set<FilePath> expected = new HashSet<>();
             expected.add(createFilePath(baseDir, "top", "sub", "app.log"));
             createFilePath(baseDir, "top", "sub", "trace.log");
@@ -417,8 +469,9 @@ public class FilePathTest {
             assertEquals(expected, new HashSet<>(Arrays.asList(result)));
     }
 
-    @Test public void listWithDefaultExcludes() throws Exception {
-        File baseDir = temp.getRoot();
+    @Test
+    void listWithDefaultExcludes() throws Exception {
+        File baseDir = temp;
             final Set<FilePath> expected = new HashSet<>();
             expected.add(createFilePath(baseDir, "top", "sub", "backup~"));
             expected.add(createFilePath(baseDir, "top", "CVS", "somefile,v"));
@@ -430,7 +483,8 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-11073")
-    @Test public void isUnix() {
+    @Test
+    void isUnix() {
         VirtualChannel dummy = Mockito.mock(VirtualChannel.class);
         FilePath winPath = new FilePath(dummy,
                 " c:\\app\\hudson\\workspace\\3.8-jelly-db\\jdk/jdk1.6.0_21/label/sqlserver/profile/sqlserver\\acceptance-tests\\distribution.zip");
@@ -453,8 +507,9 @@ public class FilePathTest {
      * Also tries to check that a problem with setting the last-modified date on Windows doesn't fail the whole copy
      * - well at least when running this test on a Windows OS. See JENKINS-11073
      */
-    @Test public void copyToWithPermission() throws IOException, InterruptedException {
-        File tmp = temp.getRoot();
+    @Test
+    void copyToWithPermission() throws IOException, InterruptedException {
+        File tmp = temp;
             File child = new File(tmp, "child");
             FilePath childP = new FilePath(child);
             childP.touch(4711);
@@ -465,7 +520,7 @@ public class FilePathTest {
             chmodTask.setPerm("0400");
             chmodTask.execute();
 
-            FilePath copy = new FilePath(channels.british, tmp.getPath()).child("copy");
+            FilePath copy = new FilePath(british, tmp.getPath()).child("copy");
             childP.copyToWithPermission(copy);
 
             assertEquals(childP.mode(), copy.mode());
@@ -477,15 +532,16 @@ public class FilePathTest {
             // Windows seems to have random failures when setting the timestamp on newly generated
             // files. So test that:
             for (int i = 0; i < 100; i++) {
-                copy = new FilePath(channels.british, tmp.getPath()).child("copy" + i);
+                copy = new FilePath(british, tmp.getPath()).child("copy" + i);
                 childP.copyToWithPermission(copy);
             }
     }
 
-    @Test public void symlinkInTar() throws Exception {
+    @Test
+    void symlinkInTar() throws Exception {
         assumeFalse(Functions.isWindows());
 
-        FilePath tmp = new FilePath(temp.getRoot());
+        FilePath tmp = new FilePath(temp);
             FilePath in = tmp.child("in");
             in.mkdirs();
             in.child("c").touch(0);
@@ -501,7 +557,8 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-13649")
-    @Test public void multiSegmentRelativePaths() {
+    @Test
+    void multiSegmentRelativePaths() {
         VirtualChannel d = Mockito.mock(VirtualChannel.class);
         FilePath winPath = new FilePath(d, "c:\\app\\jenkins\\workspace");
         FilePath nixPath = new FilePath(d, "/opt/jenkins/workspace");
@@ -514,9 +571,10 @@ public class FilePathTest {
         assertEquals("/opt/jenkins/workspace/foo/bar/manchu", new FilePath(nixPath, "foo/bar/manchu").getRemote());
     }
 
-    @Test public void validateAntFileMask() throws Exception {
-        File tmp = temp.getRoot();
-            FilePath d = new FilePath(channels.french, tmp.getPath());
+    @Test
+    void validateAntFileMask() throws Exception {
+        File tmp = temp;
+            FilePath d = new FilePath(french, tmp.getPath());
             d.child("d1/d2/d3").mkdirs();
             d.child("d1/d2/d3/f.txt").touch(0);
             d.child("d1/d2/d3/f.html").touch(0);
@@ -537,9 +595,10 @@ public class FilePathTest {
 
     @Issue("JENKINS-7214")
     @SuppressWarnings("deprecation")
-    @Test public void validateAntFileMaskBounded() throws Exception {
-        File tmp = temp.getRoot();
-            FilePath d = new FilePath(channels.french, tmp.getPath());
+    @Test
+    void validateAntFileMaskBounded() throws Exception {
+        File tmp = temp;
+            FilePath d = new FilePath(french, tmp.getPath());
             FilePath d2 = d.child("d1/d2");
             d2.mkdirs();
             for (int i = 0; i < 100; i++) {
@@ -554,10 +613,11 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-5253")
-    @Test public void testValidateCaseSensitivity() throws Exception {
+    @Test
+    void testValidateCaseSensitivity() throws Exception {
         File tmp = Util.createTempDir();
         try {
-            FilePath d = new FilePath(channels.french, tmp.getPath());
+            FilePath d = new FilePath(french, tmp.getPath());
             d.child("d1/d2/d3").mkdirs();
             d.child("d1/d2/d3/f.txt").touch(0);
             d.child("d1/d2/d3/f.html").touch(0);
@@ -573,9 +633,10 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-15418")
-    @Test public void deleteLongPathOnWindows() throws Exception {
-        File tmp = temp.getRoot();
-            FilePath d = new FilePath(channels.french, tmp.getPath());
+    @Test
+    void deleteLongPathOnWindows() throws Exception {
+        File tmp = temp;
+            FilePath d = new FilePath(french, tmp.getPath());
 
             // construct a very long path
             StringBuilder sb = new StringBuilder();
@@ -592,12 +653,13 @@ public class FilePathTest {
             File firstDirectory = new File(tmp.getAbsolutePath() + "/very");
             Util.deleteRecursive(firstDirectory);
 
-            assertFalse("Could not delete directory!", firstDirectory.exists());
+            assertFalse(firstDirectory.exists(), "Could not delete directory!");
     }
 
     @Issue("JENKINS-16215")
-    @Test public void installIfNecessaryAvoidsExcessiveDownloadsByUsingIfModifiedSince() throws Exception {
-        File tmp = temp.getRoot();
+    @Test
+    void installIfNecessaryAvoidsExcessiveDownloadsByUsingIfModifiedSince() throws Exception {
+        File tmp = temp;
             final FilePath d = new FilePath(tmp);
 
             d.child(".timestamp").touch(123000);
@@ -614,8 +676,9 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-16215")
-    @Test public void installIfNecessaryPerformsInstallation() throws Exception {
-        File tmp = temp.getRoot();
+    @Test
+    void installIfNecessaryPerformsInstallation() throws Exception {
+        File tmp = temp;
             final FilePath d = new FilePath(tmp);
 
             final HttpURLConnection con = mock(HttpURLConnection.class);
@@ -631,8 +694,9 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-26196")
-    @Test public void installIfNecessarySkipsDownloadWhenErroneous() throws Exception {
-        File tmp = temp.getRoot();
+    @Test
+    void installIfNecessarySkipsDownloadWhenErroneous() throws Exception {
+        File tmp = temp;
         final FilePath d = new FilePath(tmp);
         d.child(".timestamp").touch(123000);
         final HttpURLConnection con = mock(HttpURLConnection.class);
@@ -645,13 +709,14 @@ public class FilePathTest {
         assertFalse(d.installIfNecessaryFrom(url, new StreamTaskListener(baos, Charset.defaultCharset()), message));
         verify(con).setIfModifiedSince(123000);
         String log = baos.toString(Charset.defaultCharset());
-        assertFalse(log, log.contains(message));
-        assertTrue(log, log.contains("504 Gateway Timeout"));
+        assertFalse(log.contains(message), log);
+        assertTrue(log.contains("504 Gateway Timeout"), log);
     }
 
     @Issue("JENKINS-23507")
-    @Test public void installIfNecessaryFollowsRedirects() throws Exception {
-        File tmp = temp.getRoot();
+    @Test
+    void installIfNecessaryFollowsRedirects() throws Exception {
+        File tmp = temp;
         final FilePath d = new FilePath(tmp);
         FilePath.UrlFactory urlFactory = mock(FilePath.UrlFactory.class);
         d.setUrlFactory(urlFactory);
@@ -671,13 +736,15 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-72469")
-    @Test public void installIfNecessaryWithoutLastModifiedStrongValidator() throws Exception {
+    @Test
+    void installIfNecessaryWithoutLastModifiedStrongValidator() throws Exception {
         String strongValidator = "\"An-ETag-strong-validator\"";
         installIfNecessaryWithoutLastModified(strongValidator);
     }
 
     @Issue("JENKINS-72469")
-    @Test public void installIfNecessaryWithoutLastModifiedStrongValidatorNoQuotes() throws Exception {
+    @Test
+    void installIfNecessaryWithoutLastModifiedStrongValidatorNoQuotes() throws Exception {
         // This ETag is a violation of the spec at https://httpwg.org/specs/rfc9110.html#field.etag
         // However, better safe to handle without quotes as well, just in case
         String strongValidator = "An-ETag-strong-validator-without-quotes";
@@ -685,20 +752,23 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-72469")
-    @Test public void installIfNecessaryWithoutLastModifiedWeakValidator() throws Exception {
+    @Test
+    void installIfNecessaryWithoutLastModifiedWeakValidator() throws Exception {
         String weakValidator = "W/\"An-ETag-weak-validator\"";
         installIfNecessaryWithoutLastModified(weakValidator);
     }
 
     @Issue("JENKINS-72469")
-    @Test public void installIfNecessaryWithoutLastModifiedStrongAndWeakValidators() throws Exception {
+    @Test
+    void installIfNecessaryWithoutLastModifiedStrongAndWeakValidators() throws Exception {
         String strongValidator = "\"An-ETag-validator\"";
         String weakValidator = "W/" + strongValidator;
         installIfNecessaryWithoutLastModified(strongValidator, weakValidator);
     }
 
     @Issue("JENKINS-72469")
-    @Test public void installIfNecessaryWithoutLastModifiedWeakAndStrongValidators() throws Exception {
+    @Test
+    void installIfNecessaryWithoutLastModifiedWeakAndStrongValidators() throws Exception {
         String strongValidator = "\"An-ETag-validator\"";
         String weakValidator = "W/" + strongValidator;
         installIfNecessaryWithoutLastModified(weakValidator, strongValidator);
@@ -718,7 +788,7 @@ public class FilePathTest {
 
         final URL url = someUrlToZipFile(con);
 
-        File tmp = temp.getRoot();
+        File tmp = temp;
         final FilePath d = new FilePath(tmp);
 
         /* Initial download expected to occur */
@@ -764,8 +834,9 @@ public class FilePathTest {
     }
 
     @Issue("JENKINS-16846")
-    @Test public void moveAllChildrenTo() throws IOException, InterruptedException {
-        File tmp = temp.getRoot();
+    @Test
+    void moveAllChildrenTo() throws IOException, InterruptedException {
+        File tmp = temp;
             final String dirname = "sub";
             final File top = new File(tmp, "test");
             final File sub = new File(top, dirname);
@@ -787,8 +858,8 @@ public class FilePathTest {
 
     @Issue("JENKINS-10629")
     @Test
-    public void testEOFbrokenFlush() throws IOException, InterruptedException {
-        final File srcFolder = temp.newFolder("src");
+    void testEOFbrokenFlush() throws IOException, InterruptedException {
+        final File srcFolder = newFolder(temp, "src");
         // simulate magic structure with magic sizes:
         // |- dir/pom.xml   (2049)
         // |- pom.xml       (2049)
@@ -801,15 +872,15 @@ public class FilePathTest {
         givenSomeContentInFile(pomFile, 2049);
         FileUtils.copyFileToDirectory(pomFile, srcFolder);
 
-        final File archive = temp.newFile("archive.tar");
+        final File archive = File.createTempFile("archive.tar", null, temp);
 
         // Compress archive
         final FilePath tmpDirPath = new FilePath(srcFolder);
         int tarred = tmpDirPath.tar(Files.newOutputStream(archive.toPath()), "**");
-        assertEquals("One file should have been compressed", 3, tarred);
+        assertEquals(3, tarred, "One file should have been compressed");
 
         // Decompress
-        final File dstFolder = temp.newFolder("dst");
+        final File dstFolder = newFolder(temp, "dst");
         dstFolder.mkdirs();
         FilePath outDir = new FilePath(dstFolder);
         // and now fail when flush is bad!
@@ -817,9 +888,9 @@ public class FilePathTest {
     }
 
     @Test
-    public void chmod() throws Exception {
+    void chmod() throws Exception {
         assumeFalse(Functions.isWindows());
-        File f = temp.newFile("file");
+        File f = File.createTempFile("file", null, temp);
         FilePath fp = new FilePath(f);
         int prevMode = fp.mode();
         assertEquals(0400, chmodAndMode(fp, 0400));
@@ -829,12 +900,12 @@ public class FilePathTest {
     }
 
     @Test
-    public void chmodInvalidPermissions() throws Exception {
+    void chmodInvalidPermissions() throws Exception {
         assumeFalse(Functions.isWindows());
-        File f = temp.newFolder("folder");
+        File f = newFolder(temp, "folder");
         FilePath fp = new FilePath(f);
         int invalidMode = 01770; // Full permissions for owner and group plus sticky bit.
-        final IOException e = assertThrows("Setting sticky bit should fail", IOException.class, () -> chmodAndMode(fp, invalidMode));
+        final IOException e = assertThrows(IOException.class, () -> chmodAndMode(fp, invalidMode), "Setting sticky bit should fail");
         assertEquals("Invalid mode: " + invalidMode, e.getMessage());
     }
 
@@ -845,41 +916,42 @@ public class FilePathTest {
 
     @Issue("JENKINS-48227")
     @Test
-    public void testCreateTempDir() throws IOException, InterruptedException  {
-        final File srcFolder = temp.newFolder("src");
+    void testCreateTempDir() throws IOException, InterruptedException  {
+        final File srcFolder = newFolder(temp, "src");
         final FilePath filePath = new FilePath(srcFolder);
         FilePath x = filePath.createTempDir("jdk", "dmg");
         FilePath y = filePath.createTempDir("jdk", "pkg");
         FilePath z = filePath.createTempDir("jdk", null);
 
-        assertNotNull("FilePath x should not be null", x);
-        assertNotNull("FilePath y should not be null", y);
-        assertNotNull("FilePath z should not be null", z);
+        assertNotNull(x, "FilePath x should not be null");
+        assertNotNull(y, "FilePath y should not be null");
+        assertNotNull(z, "FilePath z should not be null");
 
         assertTrue(x.getName().contains("jdk.dmg"));
         assertTrue(y.getName().contains("jdk.pkg"));
         assertTrue(z.getName().contains("jdk.tmp"));
     }
 
-    @Test public void deleteRecursiveOnUnix() throws Exception {
+    @Test
+    void deleteRecursiveOnUnix() throws Exception {
         assumeFalse(Functions.isWindows());
-        Path targetDir = temp.newFolder("target").toPath();
+        Path targetDir = newFolder(temp, "target").toPath();
         Path targetContents = Files.createFile(targetDir.resolve("contents.txt"));
-        Path toDelete = temp.newFolder("toDelete").toPath();
+        Path toDelete = newFolder(temp, "toDelete").toPath();
         Util.createSymlink(toDelete.toFile(), "../targetDir", "link", TaskListener.NULL);
         Files.createFile(toDelete.resolve("foo"));
         Files.createFile(toDelete.resolve("bar"));
         FilePath f = new FilePath(toDelete.toFile());
         f.deleteRecursive();
-        assertTrue("symlink target should not be deleted", Files.exists(targetDir));
-        assertTrue("symlink target contents should not be deleted", Files.exists(targetContents));
-        assertFalse("could not delete target", Files.exists(toDelete));
+        assertTrue(Files.exists(targetDir), "symlink target should not be deleted");
+        assertTrue(Files.exists(targetContents), "symlink target contents should not be deleted");
+        assertFalse(Files.exists(toDelete), "could not delete target");
     }
 
     @Test
     @Issue("JENKINS-44909")
-    public void deleteSuffixesRecursive() throws Exception {
-        File deleteSuffixesRecursiveFolder = temp.newFolder("deleteSuffixesRecursive");
+    void deleteSuffixesRecursive() throws Exception {
+        File deleteSuffixesRecursiveFolder = newFolder(temp, "deleteSuffixesRecursive");
         FilePath filePath = new FilePath(deleteSuffixesRecursiveFolder);
         FilePath suffix = filePath.withSuffix(WorkspaceList.COMBINATOR + "suffixed");
         FilePath textTempFile = suffix.createTextTempFile("tmp", null, "dummy", true);
@@ -890,55 +962,58 @@ public class FilePathTest {
         assertThat(textTempFile.exists(), is(false));
     }
 
-    @Test public void deleteRecursiveOnWindows() throws Exception {
-        assumeTrue("Uses Windows-specific features", Functions.isWindows());
-        Path targetDir = temp.newFolder("targetDir").toPath();
+    @Test
+    void deleteRecursiveOnWindows() throws Exception {
+        assumeTrue(Functions.isWindows(), "Uses Windows-specific features");
+        Path targetDir = newFolder(temp, "targetDir").toPath();
         Path targetContents = Files.createFile(targetDir.resolve("contents.txt"));
-        Path toDelete = temp.newFolder("toDelete").toPath();
+        Path toDelete = newFolder(temp, "toDelete").toPath();
         File junction = WindowsUtil.createJunction(toDelete.resolve("junction").toFile(), targetDir.toFile());
         Files.createFile(toDelete.resolve("foo"));
         Files.createFile(toDelete.resolve("bar"));
         FilePath f = new FilePath(toDelete.toFile());
         f.deleteRecursive();
-        assertTrue("junction target should not be deleted", Files.exists(targetDir));
-        assertTrue("junction target contents should not be deleted", Files.exists(targetContents));
-        assertFalse("could not delete junction", junction.exists());
-        assertFalse("could not delete target", Files.exists(toDelete));
+        assertTrue(Files.exists(targetDir), "junction target should not be deleted");
+        assertTrue(Files.exists(targetContents), "junction target contents should not be deleted");
+        assertFalse(junction.exists(), "could not delete junction");
+        assertFalse(Files.exists(toDelete), "could not delete target");
     }
 
     @Issue("JENKINS-13128")
-    @Test public void copyRecursivePreservesPosixFilePermissions() throws Exception {
+    @Test
+    void copyRecursivePreservesPosixFilePermissions() throws Exception {
         assumeFalse(Functions.isWindows());
-        File src = temp.newFolder("src");
-        File dst = temp.newFolder("dst");
+        File src = newFolder(temp, "src");
+        File dst = newFolder(temp, "dst");
         Path sourceFile = Files.createFile(src.toPath().resolve("test-file"));
         Set<PosixFilePermission> allRWX = EnumSet.allOf(PosixFilePermission.class);
         Files.setPosixFilePermissions(sourceFile, allRWX);
         FilePath f = new FilePath(src);
         f.copyRecursiveTo(new FilePath(dst));
         Path destinationFile = dst.toPath().resolve("test-file");
-        assertTrue("file was not copied", Files.exists(destinationFile));
+        assertTrue(Files.exists(destinationFile), "file was not copied");
         Set<PosixFilePermission> destinationPermissions = Files.getPosixFilePermissions(destinationFile);
-        assertEquals("file permissions not copied", allRWX, destinationPermissions);
+        assertEquals(allRWX, destinationPermissions, "file permissions not copied");
     }
 
     @Issue("JENKINS-13128")
-    @Test public void copyRecursivePreservesLastModifiedTime() throws Exception {
-        File src = temp.newFolder("src");
-        File dst = temp.newFolder("dst");
+    @Test
+    void copyRecursivePreservesLastModifiedTime() throws Exception {
+        File src = newFolder(temp, "src");
+        File dst = newFolder(temp, "dst");
         Path sourceFile = Files.createFile(src.toPath().resolve("test-file"));
         FileTime mtime = FileTime.from(42L, TimeUnit.SECONDS);
         Files.setLastModifiedTime(sourceFile, mtime);
         FilePath f = new FilePath(src);
         f.copyRecursiveTo(new FilePath(dst));
         Path destinationFile = dst.toPath().resolve("test-file");
-        assertTrue("file was not copied", Files.exists(destinationFile));
-        assertEquals("file mtime was not preserved", mtime, Files.getLastModifiedTime(destinationFile));
+        assertTrue(Files.exists(destinationFile), "file was not copied");
+        assertEquals(mtime, Files.getLastModifiedTime(destinationFile), "file mtime was not preserved");
     }
 
     @Test
     @Issue("SECURITY-904")
-    public void isDescendant_regularFiles() throws IOException, InterruptedException {
+    void isDescendant_regularFiles() throws IOException, InterruptedException {
         //  root
         //      /workspace
         //          /sub
@@ -946,7 +1021,7 @@ public class FilePathTest {
         //          regular.txt
         //      /protected
         //          secret.txt
-        FilePath rootFolder = new FilePath(temp.newFolder("root"));
+        FilePath rootFolder = new FilePath(newFolder(temp, "root"));
         FilePath workspaceFolder = rootFolder.child("workspace");
         FilePath subFolder = workspaceFolder.child("sub");
         FilePath protectedFolder = rootFolder.child("protected");
@@ -988,7 +1063,7 @@ public class FilePathTest {
 
     @Test
     @Issue("SECURITY-904")
-    public void isDescendant_regularSymlinks() throws IOException, InterruptedException {
+    void isDescendant_regularSymlinks() throws IOException, InterruptedException {
         assumeFalse(Functions.isWindows());
         //  root
         //      /workspace
@@ -1004,7 +1079,7 @@ public class FilePathTest {
         //          _secrettxt => symlink to ../protected/secret.txt (illegal)
         //      /protected
         //          secret.txt
-        FilePath rootFolder = new FilePath(temp.newFolder("root"));
+        FilePath rootFolder = new FilePath(newFolder(temp, "root"));
         FilePath workspaceFolder = rootFolder.child("workspace");
         FilePath aFolder = workspaceFolder.child("a");
         FilePath bFolder = workspaceFolder.child("b");
@@ -1052,7 +1127,7 @@ public class FilePathTest {
 
     @Test
     @Issue("SECURITY-904")
-    public void isDescendant_windowsSpecificSymlinks() throws Exception {
+    void isDescendant_windowsSpecificSymlinks() throws Exception {
         assumeTrue(Functions.isWindows());
         //  root
         //      /workspace
@@ -1067,7 +1142,7 @@ public class FilePathTest {
         //          _protected => junction to ../protected (illegal)
         //      /protected
         //          secret.txt
-        File root = temp.newFolder("root");
+        File root = newFolder(temp, "root");
         FilePath rootFolder = new FilePath(root);
         FilePath workspaceFolder = rootFolder.child("workspace");
         FilePath aFolder = workspaceFolder.child("a");
@@ -1118,7 +1193,7 @@ public class FilePathTest {
     @Issue("SECURITY-904")
     public void isDescendant_throwIfParentDoesNotExist_symlink() throws Exception {
         assumeFalse(Functions.isWindows());
-        FilePath rootFolder = new FilePath(temp.newFolder("root"));
+        FilePath rootFolder = new FilePath(newFolder(temp, "root"));
         FilePath aFolder = rootFolder.child("a");
         aFolder.mkdirs();
         FilePath linkToNonexistent = aFolder.child("linkToNonexistent");
@@ -1129,22 +1204,22 @@ public class FilePathTest {
 
     @Issue("SECURITY-904")
     public void isDescendant_throwIfParentDoesNotExist_directNonexistent() throws Exception {
-        FilePath rootFolder = new FilePath(temp.newFolder("root"));
+        FilePath rootFolder = new FilePath(newFolder(temp, "root"));
         FilePath nonexistent = rootFolder.child("nonexistent");
         assertThat(nonexistent.isDescendant("."), is(false));
     }
 
     @Test
     @Issue("SECURITY-904")
-    public void isDescendant_throwIfAbsolutePathGiven() throws Exception {
-        FilePath rootFolder = new FilePath(temp.newFolder("root"));
+    void isDescendant_throwIfAbsolutePathGiven() throws Exception {
+        FilePath rootFolder = new FilePath(newFolder(temp, "root"));
         rootFolder.mkdirs();
-        assertThrows(IllegalArgumentException.class, () -> rootFolder.isDescendant(temp.newFile().getAbsolutePath()));
+        assertThrows(IllegalArgumentException.class, () -> rootFolder.isDescendant(File.createTempFile("junit", null, temp).getAbsolutePath()));
     }
 
     @Test
     @Issue("SECURITY-904")
-    public void isDescendant_worksEvenInSymbolicWorkspace() throws Exception {
+    void isDescendant_worksEvenInSymbolicWorkspace() throws Exception {
         assumeFalse(Functions.isWindows());
         //  root
         //      /w
@@ -1162,7 +1237,7 @@ public class FilePathTest {
         //          _secrettxt => symlink to ../protected/secret.txt (illegal)
         //      /protected
         //          secret.txt
-        FilePath rootFolder = new FilePath(temp.newFolder("root"));
+        FilePath rootFolder = new FilePath(newFolder(temp, "root"));
         FilePath workspaceFolder = rootFolder.child("workspace");
         FilePath aFolder = workspaceFolder.child("a");
         FilePath bFolder = workspaceFolder.child("b");
@@ -1213,4 +1288,13 @@ public class FilePathTest {
         assertFalse(symbolicWorkspace.isDescendant("./_secrettxt"));
         assertFalse(symbolicWorkspace.isDescendant("_secrettxt2"));
     }
+
+    private static File newFolder(File root, String... subDirs) throws IOException {
+        String subFolder = String.join("/", subDirs);
+        File result = new File(root, subFolder);
+        if (!result.mkdirs()) {
+            throw new IOException("Couldn't create folders " + root);
+        }
+        return result;
+    }
 }

core/src/test/java/hudson/FunctionsTest.java

@@ -30,9 +30,9 @@ import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.nullValue;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.mockStatic;
 import static org.mockito.Mockito.when;
@@ -56,17 +56,18 @@ import java.util.logging.LogRecord;
 import java.util.regex.Matcher;
 import java.util.regex.Pattern;
 import jenkins.model.Jenkins;
-import org.junit.Ignore;
-import org.junit.Test;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
 import org.jvnet.hudson.test.Issue;
 import org.kohsuke.stapler.Ancestor;
 import org.kohsuke.stapler.Stapler;
 import org.kohsuke.stapler.StaplerRequest2;
 import org.mockito.MockedStatic;
 
-public class FunctionsTest {
+class FunctionsTest {
+
     @Test
-    public void testGetActionUrl_absoluteUriWithAuthority() {
+    void testGetActionUrl_absoluteUriWithAuthority() {
         String[] uris = {
             "http://example.com/foo/bar",
             "https://example.com/foo/bar",
@@ -81,7 +82,7 @@ public class FunctionsTest {
 
     @Test
     @Issue("JENKINS-7725")
-    public void testGetActionUrl_absoluteUriWithoutAuthority() {
+    void testGetActionUrl_absoluteUriWithoutAuthority() {
         String[] uris = {
             "mailto:nobody@example.com",
             "mailto:nobody@example.com?subject=hello",
@@ -94,7 +95,7 @@ public class FunctionsTest {
     }
 
     @Test
-    public void testGetActionUrl_absolutePath() {
+    void testGetActionUrl_absolutePath() {
         String contextPath = "/jenkins";
         StaplerRequest2 req = createMockRequest(contextPath);
         String[] paths = {
@@ -112,7 +113,7 @@ public class FunctionsTest {
     }
 
     @Test
-    public void testGetActionUrl_relativePath() {
+    void testGetActionUrl_relativePath() {
         String contextPath = "/jenkins";
         String itUrl = "iturl/";
         StaplerRequest2 req = createMockRequest(contextPath);
@@ -131,7 +132,7 @@ public class FunctionsTest {
     }
 
     @Test
-    public void testGetRelativeLinkTo_JobContainedInView() {
+    void testGetRelativeLinkTo_JobContainedInView() {
         String contextPath = "/jenkins";
         StaplerRequest2 req = createMockRequest(contextPath);
         try (
@@ -153,7 +154,7 @@ public class FunctionsTest {
     }
 
     @Test
-    public void testGetRelativeLinkTo_JobFromComputer() {
+    void testGetRelativeLinkTo_JobFromComputer() {
         String contextPath = "/jenkins";
         StaplerRequest2 req = createMockRequest(contextPath);
         try (
@@ -171,9 +172,9 @@ public class FunctionsTest {
         }
     }
 
-    @Ignore("too expensive to make it correct")
+    @Disabled("too expensive to make it correct")
     @Test
-    public void testGetRelativeLinkTo_JobNotContainedInView() {
+    void testGetRelativeLinkTo_JobNotContainedInView() {
         String contextPath = "/jenkins";
         StaplerRequest2 req = createMockRequest(contextPath);
         try (
@@ -196,7 +197,7 @@ public class FunctionsTest {
     private interface TopLevelItemAndItemGroup<T extends TopLevelItem> extends TopLevelItem, ItemGroup<T>, ViewGroup {}
 
     @Test
-    public void testGetRelativeLinkTo_JobContainedInViewWithinItemGroup() {
+    void testGetRelativeLinkTo_JobContainedInViewWithinItemGroup() {
         String contextPath = "/jenkins";
         StaplerRequest2 req = createMockRequest(contextPath);
         try (
@@ -219,7 +220,8 @@ public class FunctionsTest {
     }
 
     @Issue("JENKINS-17713")
-    @Test public void getRelativeLinkTo_MavenModules() {
+    @Test
+    void getRelativeLinkTo_MavenModules() {
         StaplerRequest2 req = createMockRequest("/jenkins");
         try (
                 MockedStatic<Stapler> mocked = mockStatic(Stapler.class);
@@ -239,7 +241,7 @@ public class FunctionsTest {
     }
 
     @Test
-    public void testGetRelativeDisplayName() {
+    void testGetRelativeDisplayName() {
         Item i = mock(Item.class);
         when(i.getName()).thenReturn("jobName");
         when(i.getFullDisplayName()).thenReturn("displayName");
@@ -247,7 +249,7 @@ public class FunctionsTest {
     }
 
     @Test
-    public void testGetRelativeDisplayNameInsideItemGroup() {
+    void testGetRelativeDisplayNameInsideItemGroup() {
         Item i = mock(Item.class);
         when(i.getName()).thenReturn("jobName");
         when(i.getDisplayName()).thenReturn("displayName");
@@ -297,7 +299,7 @@ public class FunctionsTest {
     }
 
     @Test
-    public void testGetActionUrl_unparseable() {
+    void testGetActionUrl_unparseable() {
         assertNull(Functions.getActionUrl(null, createMockAction("http://example.net/stuff?something=^woohoo")));
     }
 
@@ -315,7 +317,7 @@ public class FunctionsTest {
 
     @Test
     @Issue("JENKINS-16630")
-    public void testHumanReadableFileSize() {
+    void testHumanReadableFileSize() {
         Locale defaultLocale = Locale.getDefault();
         try {
             Locale.setDefault(Locale.ENGLISH);
@@ -335,7 +337,7 @@ public class FunctionsTest {
 
     @Issue("JENKINS-17030")
     @Test
-    public void testBreakableString() {
+    void testBreakableString() {
 
         assertBrokenAs("Hello world!", "Hello world!");
         assertBrokenAs("Hello-world!", "Hello", "-world!");
@@ -363,110 +365,129 @@ public class FunctionsTest {
     }
 
     @Issue("JENKINS-20800")
-    @Test public void printLogRecordHtml() {
+    @Test
+    void printLogRecordHtml() {
         LogRecord lr = new LogRecord(Level.INFO, "Bad input <xml/>");
         lr.setLoggerName("test");
         assertEquals("Bad input &lt;xml/&gt;\n", Functions.printLogRecordHtml(lr, null)[3]);
     }
 
-    @Test public void printLogRecordHtmlNoLogger() {
+    @Test
+    void printLogRecordHtmlNoLogger() {
         LogRecord lr = new LogRecord(Level.INFO, "<discarded/>");
         assertEquals("&lt;discarded/&gt;\n", Functions.printLogRecordHtml(lr, null)[3]);
     }
 
     @Test
-    public void extractPluginNameFromIconSrcHandlesNull() {
+    void extractPluginNameFromIconSrcHandlesNull() {
         String result = Functions.extractPluginNameFromIconSrc(null);
 
         assertThat(result, is(emptyString()));
     }
 
     @Test
-    public void extractPluginNameFromIconSrcHandlesEmptyString() {
+    void extractPluginNameFromIconSrcHandlesEmptyString() {
         String result = Functions.extractPluginNameFromIconSrc("");
 
         assertThat(result, is(emptyString()));
     }
 
     @Test
-    public void extractPluginNameFromIconSrcOnlyReturnsPluginFromStart() {
+    void extractPluginNameFromIconSrcOnlyReturnsPluginFromStart() {
         String result = Functions.extractPluginNameFromIconSrc("symbol-plugin-mailer plugin-design-library");
 
         assertThat(result, is(equalTo("design-library")));
     }
 
     @Test
-    public void extractPluginNameFromIconSrcExtractsPlugin() {
+    void extractPluginNameFromIconSrcExtractsPlugin() {
         String result = Functions.extractPluginNameFromIconSrc("symbol-padlock plugin-design-library");
 
         assertThat(result, is(equalTo("design-library")));
     }
 
     @Test
-    public void extractPluginNameFromIconSrcWhichContainsPluginWordInThePluginName() {
+    void extractPluginNameFromIconSrcWhichContainsPluginWordInThePluginName() {
         String result = Functions.extractPluginNameFromIconSrc("symbol-padlock plugin-design-library-plugin");
 
         assertThat(result, is(equalTo("design-library-plugin")));
     }
 
     @Issue("JDK-6507809")
-    @Test public void printThrowable() {
+    @Test
+    void printThrowable() {
         // Basics: a single exception. No change.
         assertPrintThrowable(new Stack("java.lang.NullPointerException: oops", "p.C.method1:17", "m.Main.main:1"),
-            "java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "\tat m.Main.main(Main.java:1)\n",
-            "java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "\tat m.Main.main(Main.java:1)\n");
+                """
+                        java.lang.NullPointerException: oops
+                        \tat p.C.method1(C.java:17)
+                        \tat m.Main.main(Main.java:1)
+                        """,
+                """
+                        java.lang.NullPointerException: oops
+                        \tat p.C.method1(C.java:17)
+                        \tat m.Main.main(Main.java:1)
+                        """);
         // try {…} catch (Exception x) {throw new IllegalStateException(x);}
         assertPrintThrowable(new Stack("java.lang.IllegalStateException: java.lang.NullPointerException: oops", "p.C.method1:19", "m.Main.main:1").
                        cause(new Stack("java.lang.NullPointerException: oops", "p.C.method2:23", "p.C.method1:17", "m.Main.main:1")),
-            "java.lang.IllegalStateException: java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method1(C.java:19)\n" +
-            "\tat m.Main.main(Main.java:1)\n" +
-            "Caused by: java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method2(C.java:23)\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "\t... 1 more\n",
-            "java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method2(C.java:23)\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "Caused: java.lang.IllegalStateException\n" +
-            "\tat p.C.method1(C.java:19)\n" +
-            "\tat m.Main.main(Main.java:1)\n");
+                """
+                        java.lang.IllegalStateException: java.lang.NullPointerException: oops
+                        \tat p.C.method1(C.java:19)
+                        \tat m.Main.main(Main.java:1)
+                        Caused by: java.lang.NullPointerException: oops
+                        \tat p.C.method2(C.java:23)
+                        \tat p.C.method1(C.java:17)
+                        \t... 1 more
+                        """,
+                """
+                        java.lang.NullPointerException: oops
+                        \tat p.C.method2(C.java:23)
+                        \tat p.C.method1(C.java:17)
+                        Caused: java.lang.IllegalStateException
+                        \tat p.C.method1(C.java:19)
+                        \tat m.Main.main(Main.java:1)
+                        """);
         // try {…} catch (Exception x) {throw new IllegalStateException("more info");}
         assertPrintThrowable(new Stack("java.lang.IllegalStateException: more info", "p.C.method1:19", "m.Main.main:1").
                        cause(new Stack("java.lang.NullPointerException: oops", "p.C.method2:23", "p.C.method1:17", "m.Main.main:1")),
-            "java.lang.IllegalStateException: more info\n" +
-            "\tat p.C.method1(C.java:19)\n" +
-            "\tat m.Main.main(Main.java:1)\n" +
-            "Caused by: java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method2(C.java:23)\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "\t... 1 more\n",
-            "java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method2(C.java:23)\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "Caused: java.lang.IllegalStateException: more info\n" +
-            "\tat p.C.method1(C.java:19)\n" +
-            "\tat m.Main.main(Main.java:1)\n");
+                """
+                        java.lang.IllegalStateException: more info
+                        \tat p.C.method1(C.java:19)
+                        \tat m.Main.main(Main.java:1)
+                        Caused by: java.lang.NullPointerException: oops
+                        \tat p.C.method2(C.java:23)
+                        \tat p.C.method1(C.java:17)
+                        \t... 1 more
+                        """,
+                """
+                        java.lang.NullPointerException: oops
+                        \tat p.C.method2(C.java:23)
+                        \tat p.C.method1(C.java:17)
+                        Caused: java.lang.IllegalStateException: more info
+                        \tat p.C.method1(C.java:19)
+                        \tat m.Main.main(Main.java:1)
+                        """);
         // try {…} catch (Exception x) {throw new IllegalStateException("more info: " + x);}
         assertPrintThrowable(new Stack("java.lang.IllegalStateException: more info: java.lang.NullPointerException: oops", "p.C.method1:19", "m.Main.main:1").
                        cause(new Stack("java.lang.NullPointerException: oops", "p.C.method2:23", "p.C.method1:17", "m.Main.main:1")),
-            "java.lang.IllegalStateException: more info: java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method1(C.java:19)\n" +
-            "\tat m.Main.main(Main.java:1)\n" +
-            "Caused by: java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method2(C.java:23)\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "\t... 1 more\n",
-            "java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method2(C.java:23)\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "Caused: java.lang.IllegalStateException: more info\n" +
-            "\tat p.C.method1(C.java:19)\n" +
-            "\tat m.Main.main(Main.java:1)\n");
+                """
+                        java.lang.IllegalStateException: more info: java.lang.NullPointerException: oops
+                        \tat p.C.method1(C.java:19)
+                        \tat m.Main.main(Main.java:1)
+                        Caused by: java.lang.NullPointerException: oops
+                        \tat p.C.method2(C.java:23)
+                        \tat p.C.method1(C.java:17)
+                        \t... 1 more
+                        """,
+                """
+                        java.lang.NullPointerException: oops
+                        \tat p.C.method2(C.java:23)
+                        \tat p.C.method1(C.java:17)
+                        Caused: java.lang.IllegalStateException: more info
+                        \tat p.C.method1(C.java:19)
+                        \tat m.Main.main(Main.java:1)
+                        """);
         // Synthetic stack showing an exception made elsewhere, such as happens with hudson.remoting.Channel.attachCallSiteStackTrace.
         Throwable t = new Stack("remote.Exception: oops", "remote.Place.method:17", "remote.Service.run:9");
         StackTraceElement[] callSite = new Stack("wrapped.Exception", "local.Side.call:11", "local.Main.main:1").getStackTrace();
@@ -477,18 +498,22 @@ public class FunctionsTest {
         System.arraycopy(callSite, 0, combined, original.length + 1, callSite.length);
         t.setStackTrace(combined);
         assertPrintThrowable(t,
-            "remote.Exception: oops\n" +
-            "\tat remote.Place.method(Place.java:17)\n" +
-            "\tat remote.Service.run(Service.java:9)\n" +
-            "\tat ......remote call(Native Method)\n" +
-            "\tat local.Side.call(Side.java:11)\n" +
-            "\tat local.Main.main(Main.java:1)\n",
-            "remote.Exception: oops\n" +
-            "\tat remote.Place.method(Place.java:17)\n" +
-            "\tat remote.Service.run(Service.java:9)\n" +
-            "\tat ......remote call(Native Method)\n" +
-            "\tat local.Side.call(Side.java:11)\n" +
-            "\tat local.Main.main(Main.java:1)\n");
+                """
+                        remote.Exception: oops
+                        \tat remote.Place.method(Place.java:17)
+                        \tat remote.Service.run(Service.java:9)
+                        \tat ......remote call(Native Method)
+                        \tat local.Side.call(Side.java:11)
+                        \tat local.Main.main(Main.java:1)
+                        """,
+                """
+                        remote.Exception: oops
+                        \tat remote.Place.method(Place.java:17)
+                        \tat remote.Service.run(Service.java:9)
+                        \tat ......remote call(Native Method)
+                        \tat local.Side.call(Side.java:11)
+                        \tat local.Main.main(Main.java:1)
+                        """);
         // Same but now using a cause on the remote side.
         t = new Stack("remote.Wrapper: remote.Exception: oops", "remote.Place.method2:19", "remote.Service.run:9").cause(new Stack("remote.Exception: oops", "remote.Place.method1:11", "remote.Place.method2:17", "remote.Service.run:9"));
         callSite = new Stack("wrapped.Exception", "local.Side.call:11", "local.Main.main:1").getStackTrace();
@@ -499,16 +524,18 @@ public class FunctionsTest {
         System.arraycopy(callSite, 0, combined, original.length + 1, callSite.length);
         t.setStackTrace(combined);
         assertPrintThrowable(t,
-            "remote.Wrapper: remote.Exception: oops\n" +
-            "\tat remote.Place.method2(Place.java:19)\n" +
-            "\tat remote.Service.run(Service.java:9)\n" +
-            "\tat ......remote call(Native Method)\n" +
-            "\tat local.Side.call(Side.java:11)\n" +
-            "\tat local.Main.main(Main.java:1)\n" +
-            "Caused by: remote.Exception: oops\n" +
-            "\tat remote.Place.method1(Place.java:11)\n" +
-            "\tat remote.Place.method2(Place.java:17)\n" +
-            "\tat remote.Service.run(Service.java:9)\n",
+                """
+                        remote.Wrapper: remote.Exception: oops
+                        \tat remote.Place.method2(Place.java:19)
+                        \tat remote.Service.run(Service.java:9)
+                        \tat ......remote call(Native Method)
+                        \tat local.Side.call(Side.java:11)
+                        \tat local.Main.main(Main.java:1)
+                        Caused by: remote.Exception: oops
+                        \tat remote.Place.method1(Place.java:11)
+                        \tat remote.Place.method2(Place.java:17)
+                        \tat remote.Service.run(Service.java:9)
+                        """,
             "remote.Exception: oops\n" +
             "\tat remote.Place.method1(Place.java:11)\n" +
             "\tat remote.Place.method2(Place.java:17)\n" +
@@ -525,40 +552,44 @@ public class FunctionsTest {
                   suppressed(new Stack("java.io.IOException: could not close", "p.C.close:99", "p.C.method1:18", "m.Main.main:1"),
                              new Stack("java.io.IOException: java.lang.NullPointerException", "p.C.flush:77", "p.C.method1:18", "m.Main.main:1").
                        cause(new Stack("java.lang.NullPointerException", "p.C.findFlushee:70", "p.C.flush:75", "p.C.method1:18", "m.Main.main:1"))),
-            "java.lang.IllegalStateException: java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method1(C.java:19)\n" +
-            "\tat m.Main.main(Main.java:1)\n" +
-            "\tSuppressed: java.io.IOException: could not close\n" +
-            "\t\tat p.C.close(C.java:99)\n" +
-            "\t\tat p.C.method1(C.java:18)\n" +
-            "\t\t... 1 more\n" +
-            "\tSuppressed: java.io.IOException: java.lang.NullPointerException\n" +
-            "\t\tat p.C.flush(C.java:77)\n" +
-            "\t\tat p.C.method1(C.java:18)\n" +
-            "\t\t... 1 more\n" +
-            "\tCaused by: java.lang.NullPointerException\n" +
-            "\t\tat p.C.findFlushee(C.java:70)\n" +
-            "\t\tat p.C.flush(C.java:75)\n" +
-            "\t\t... 2 more\n" +
-            "Caused by: java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method2(C.java:23)\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "\t... 1 more\n",
-            "java.lang.NullPointerException: oops\n" +
-            "\tat p.C.method2(C.java:23)\n" +
-            "\tat p.C.method1(C.java:17)\n" +
-            "Also:   java.io.IOException: could not close\n" +
-            "\t\tat p.C.close(C.java:99)\n" +
-            "\t\tat p.C.method1(C.java:18)\n" +
-            "Also:   java.lang.NullPointerException\n" +
-            "\t\tat p.C.findFlushee(C.java:70)\n" +
-            "\t\tat p.C.flush(C.java:75)\n" +
-            "\tCaused: java.io.IOException\n" +
-            "\t\tat p.C.flush(C.java:77)\n" +
-            "\t\tat p.C.method1(C.java:18)\n" +
-            "Caused: java.lang.IllegalStateException\n" +
-            "\tat p.C.method1(C.java:19)\n" +
-            "\tat m.Main.main(Main.java:1)\n");
+                """
+                        java.lang.IllegalStateException: java.lang.NullPointerException: oops
+                        \tat p.C.method1(C.java:19)
+                        \tat m.Main.main(Main.java:1)
+                        \tSuppressed: java.io.IOException: could not close
+                        \t\tat p.C.close(C.java:99)
+                        \t\tat p.C.method1(C.java:18)
+                        \t\t... 1 more
+                        \tSuppressed: java.io.IOException: java.lang.NullPointerException
+                        \t\tat p.C.flush(C.java:77)
+                        \t\tat p.C.method1(C.java:18)
+                        \t\t... 1 more
+                        \tCaused by: java.lang.NullPointerException
+                        \t\tat p.C.findFlushee(C.java:70)
+                        \t\tat p.C.flush(C.java:75)
+                        \t\t... 2 more
+                        Caused by: java.lang.NullPointerException: oops
+                        \tat p.C.method2(C.java:23)
+                        \tat p.C.method1(C.java:17)
+                        \t... 1 more
+                        """,
+                """
+                        java.lang.NullPointerException: oops
+                        \tat p.C.method2(C.java:23)
+                        \tat p.C.method1(C.java:17)
+                        Also:   java.io.IOException: could not close
+                        \t\tat p.C.close(C.java:99)
+                        \t\tat p.C.method1(C.java:18)
+                        Also:   java.lang.NullPointerException
+                        \t\tat p.C.findFlushee(C.java:70)
+                        \t\tat p.C.flush(C.java:75)
+                        \tCaused: java.io.IOException
+                        \t\tat p.C.flush(C.java:77)
+                        \t\tat p.C.method1(C.java:18)
+                        Caused: java.lang.IllegalStateException
+                        \tat p.C.method1(C.java:19)
+                        \tat m.Main.main(Main.java:1)
+                        """);
         // Custom printStackTrace implementations:
         assertPrintThrowable(new Throwable() {
             @Override
@@ -576,28 +607,36 @@ public class FunctionsTest {
         if (getVersion().isNewerThanOrEqualTo(new VersionNumber("11.0.9")) ||
                 (getVersion().getDigitAt(0) == 8 && getVersion().isNewerThanOrEqualTo(new VersionNumber("8.0.272")))) {
             assertPrintThrowable(stack1,
-                    "p.Exc1\n" +
-                            "\tat p.C.method1(C.java:17)\n" +
-                            "Caused by: p.Exc2\n" +
-                            "\tat p.C.method2(C.java:27)\n" +
-                            "Caused by: [CIRCULAR REFERENCE: p.Exc1]\n",
-                    "<cycle to p.Exc1>\n" +
-                            "Caused: p.Exc2\n" +
-                            "\tat p.C.method2(C.java:27)\n" +
-                            "Caused: p.Exc1\n" +
-                            "\tat p.C.method1(C.java:17)\n");
+                    """
+                            p.Exc1
+                            \tat p.C.method1(C.java:17)
+                            Caused by: p.Exc2
+                            \tat p.C.method2(C.java:27)
+                            Caused by: [CIRCULAR REFERENCE: p.Exc1]
+                            """,
+                    """
+                            <cycle to p.Exc1>
+                            Caused: p.Exc2
+                            \tat p.C.method2(C.java:27)
+                            Caused: p.Exc1
+                            \tat p.C.method1(C.java:17)
+                            """);
         } else {
             assertPrintThrowable(stack1,
-                    "p.Exc1\n" +
-                            "\tat p.C.method1(C.java:17)\n" +
-                            "Caused by: p.Exc2\n" +
-                            "\tat p.C.method2(C.java:27)\n" +
-                            "\t[CIRCULAR REFERENCE:p.Exc1]\n",
-                    "<cycle to p.Exc1>\n" +
-                            "Caused: p.Exc2\n" +
-                            "\tat p.C.method2(C.java:27)\n" +
-                            "Caused: p.Exc1\n" +
-                            "\tat p.C.method1(C.java:17)\n");
+                    """
+                            p.Exc1
+                            \tat p.C.method1(C.java:17)
+                            Caused by: p.Exc2
+                            \tat p.C.method2(C.java:27)
+                            \t[CIRCULAR REFERENCE:p.Exc1]
+                            """,
+                    """
+                            <cycle to p.Exc1>
+                            Caused: p.Exc2
+                            \tat p.C.method2(C.java:27)
+                            Caused: p.Exc1
+                            \tat p.C.method1(C.java:17)
+                            """);
         }
     }
 
@@ -651,42 +690,42 @@ public class FunctionsTest {
     }
 
     @Test
-    public void tryGetIcon_shouldReturnNullForNull() throws Exception {
+    void tryGetIcon_shouldReturnNullForNull() {
         assertThat(Functions.tryGetIcon(null), is(nullValue()));
     }
 
     @Test
-    public void tryGetIcon_shouldReturnNullForSymbol() throws Exception {
+    void tryGetIcon_shouldReturnNullForSymbol() {
         assertThat(Functions.tryGetIcon("symbol-search"), is(nullValue()));
     }
 
     @Test
-    public void tryGetIcon_shouldReturnMetadataForExactSpec() throws Exception {
+    void tryGetIcon_shouldReturnMetadataForExactSpec() {
         assertThat(Functions.tryGetIcon("icon-help icon-sm"), is(not(nullValue())));
     }
 
     @Test
-    public void tryGetIcon_shouldReturnMetadataForExtraSpec() throws Exception {
+    void tryGetIcon_shouldReturnMetadataForExtraSpec() {
         assertThat(Functions.tryGetIcon("icon-help icon-sm extra-class"), is(not(nullValue())));
     }
 
     @Test
-    public void tryGetIcon_shouldReturnMetadataForFilename() throws Exception {
+    void tryGetIcon_shouldReturnMetadataForFilename() {
         assertThat(Functions.tryGetIcon("help.svg"), is(not(nullValue())));
     }
 
     @Test
-    public void tryGetIcon_shouldReturnMetadataForUrl() throws Exception {
+    void tryGetIcon_shouldReturnMetadataForUrl() {
         assertThat(Functions.tryGetIcon("48x48/green.gif"), is(not(nullValue())));
     }
 
     @Test
-    public void tryGetIcon_shouldReturnNullForUnknown() throws Exception {
+    void tryGetIcon_shouldReturnNullForUnknown() {
         assertThat(Functions.tryGetIcon("icon-nosuchicon"), is(nullValue()));
     }
 
     @Test
-    public void guessIcon() throws Exception {
+    void guessIcon() {
         Jenkins.RESOURCE_PATH = "/static/12345678";
         assertEquals("/jenkins/static/12345678/images/48x48/green.gif", Functions.guessIcon("jenkins/images/48x48/green.gif", "/jenkins"));
         assertEquals("/jenkins/static/12345678/images/48x48/green.gif", Functions.guessIcon("/jenkins/images/48x48/green.gif", "/jenkins"));

core/src/test/java/hudson/GetLocaleStaticHelpUrlTest.java

@@ -40,10 +40,10 @@ import org.jvnet.hudson.test.Issue;
 import org.kohsuke.stapler.StaplerRequest2;
 import org.kohsuke.stapler.lang.Klass;
 
-public class GetLocaleStaticHelpUrlTest {
+class GetLocaleStaticHelpUrlTest {
 
     @Test
-    public void getStaticHelpUrlAcceptEnResDefault() {
+    void getStaticHelpUrlAcceptEnResDefault() {
         // Accept-Language: en
         StaplerRequest2 req = mockStaplerRequest2(
                 Locale.ENGLISH
@@ -58,7 +58,7 @@ public class GetLocaleStaticHelpUrlTest {
     }
 
     @Test
-    public void getStaticHelpUrlAcceptDeResDeNoCountry() {
+    void getStaticHelpUrlAcceptDeResDeNoCountry() {
         // Accept-Language: de-DE,de;q=0.9,en;q=0.8
         StaplerRequest2 req = mockStaplerRequest2(
                 Locale.GERMANY,
@@ -76,7 +76,7 @@ public class GetLocaleStaticHelpUrlTest {
     }
 
     @Test
-    public void getStaticHelpUrlAcceptDeResDeCountry() {
+    void getStaticHelpUrlAcceptDeResDeCountry() {
         // Accept-Language: de-DE,de;q=0.9,en;q=0.8
         StaplerRequest2 req = mockStaplerRequest2(
                 Locale.GERMANY,
@@ -94,7 +94,7 @@ public class GetLocaleStaticHelpUrlTest {
     }
 
     @Test
-    public void getStaticHelpUrlAcceptDeResBoth() {
+    void getStaticHelpUrlAcceptDeResBoth() {
         // Accept-Language: de-DE,de;q=0.9,en;q=0.8
         StaplerRequest2 req = mockStaplerRequest2(
                 Locale.GERMANY,
@@ -113,7 +113,7 @@ public class GetLocaleStaticHelpUrlTest {
     }
 
     @Test
-    public void getStaticHelpUrlAcceptZhResDefault() {
+    void getStaticHelpUrlAcceptZhResDefault() {
         // Accept-Language: zh,zh-CN;q=0.9,en-US;q=0.8,en;q=0.7,zh-TW;q=0.6
         StaplerRequest2 req = mockStaplerRequest2(
                 Locale.CHINESE,
@@ -132,7 +132,7 @@ public class GetLocaleStaticHelpUrlTest {
     }
 
     @Test
-    public void getStaticHelpUrlAcceptZhResZhCountry() {
+    void getStaticHelpUrlAcceptZhResZhCountry() {
         // Accept-Language: zh,zh-CN;q=0.9,en-US;q=0.8,en;q=0.7,zh-TW;q=0.6
         StaplerRequest2 req = mockStaplerRequest2(
                 Locale.CHINESE,
@@ -152,7 +152,7 @@ public class GetLocaleStaticHelpUrlTest {
     }
 
     @Test
-    public void getStaticHelpUrlAcceptZhResBoth() {
+    void getStaticHelpUrlAcceptZhResBoth() {
         // Accept-Language: zh,zh-CN;q=0.9,en-US;q=0.8,en;q=0.7,zh-TW;q=0.6
         StaplerRequest2 req = mockStaplerRequest2(
                 Locale.CHINESE,
@@ -172,7 +172,7 @@ public class GetLocaleStaticHelpUrlTest {
     }
 
     @Test
-    public void getStaticHelpUrlAcceptZhResMore() {
+    void getStaticHelpUrlAcceptZhResMore() {
         // Accept-Language: zh,zh-CN;q=0.9,en-US;q=0.8,en;q=0.7,zh-TW;q=0.6
         StaplerRequest2 req = mockStaplerRequest2(
                 Locale.CHINESE,
@@ -194,7 +194,7 @@ public class GetLocaleStaticHelpUrlTest {
 
     @Issue("JENKINS-73246")
     @Test
-    public void getStaticHelpUrlAcceptEnFirst() {
+    void getStaticHelpUrlAcceptEnFirst() {
         // Accept-Language: en-US,en;q=0.9,de;q=0.8
         StaplerRequest2 req = mockStaplerRequest2(
                 Locale.US,

core/src/test/java/hudson/LauncherTest.java

@@ -24,39 +24,85 @@
 
 package hudson;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotEquals;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assume.assumeFalse;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assumptions.assumeFalse;
 
 import hudson.model.StreamBuildListener;
 import hudson.model.TaskListener;
+import hudson.remoting.Channel;
+import hudson.remoting.ChannelBuilder;
+import hudson.remoting.FastPipedInputStream;
+import hudson.remoting.FastPipedOutputStream;
 import hudson.util.ProcessTree;
 import hudson.util.StreamTaskListener;
 import java.io.ByteArrayOutputStream;
 import java.io.File;
+import java.io.IOException;
+import java.io.UncheckedIOException;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
 import jenkins.security.MasterToSlaveCallable;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.jvnet.hudson.test.Issue;
 
-public class LauncherTest {
+class LauncherTest {
 
-    @Rule public ChannelRule channels = new ChannelRule();
-    @Rule public TemporaryFolder temp = new TemporaryFolder();
+    @TempDir
+    private File temp;
+
+    /**
+     * Two channels that are connected to each other, but shares the same classloader.
+     */
+    private Channel french;
+    private Channel british;
+    private ExecutorService executors;
+
+    @BeforeEach
+    void setUp() throws Exception {
+        executors = Executors.newCachedThreadPool();
+        final FastPipedInputStream p1i = new FastPipedInputStream();
+        final FastPipedInputStream p2i = new FastPipedInputStream();
+        final FastPipedOutputStream p1o = new FastPipedOutputStream(p1i);
+        final FastPipedOutputStream p2o = new FastPipedOutputStream(p2i);
+
+        Future<Channel> f1 = executors.submit(() -> new ChannelBuilder("This side of the channel", executors).withMode(Channel.Mode.BINARY).build(p1i, p2o));
+        Future<Channel> f2 = executors.submit(() -> new ChannelBuilder("The other side of the channel", executors).withMode(Channel.Mode.BINARY).build(p2i, p1o));
+        french = f1.get();
+        british = f2.get();
+    }
+
+    @AfterEach
+    void tearDown() {
+        try {
+            french.close(); // this will automatically initiate the close on the other channel, too.
+            french.join();
+            british.join();
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        } catch (InterruptedException x) {
+            throw new AssertionError(x);
+        }
+        executors.shutdownNow();
+    }
 
     @Issue("JENKINS-4611")
-    @Test public void remoteKill() throws Exception {
+    @Test
+    void remoteKill() throws Exception {
         assumeFalse(Functions.isWindows());
 
-        File tmp = temp.newFile();
+        File tmp = File.createTempFile("junit", null, temp);
 
-            FilePath f = new FilePath(channels.french, tmp.getPath());
+            FilePath f = new FilePath(french, tmp.getPath());
             Launcher l = f.createLauncher(StreamTaskListener.fromStderr());
             Proc p = l.launch().cmds("sh", "-c", "echo $$$$ > " + tmp + "; sleep 30").stdout(System.out).stderr(System.err).start();
             while (!tmp.exists())
@@ -66,10 +112,10 @@ public class LauncherTest {
             assertNotEquals(0, p.join());
             long end = System.currentTimeMillis();
             long terminationTime = end - start;
-            assertTrue("Join did not finish promptly. The completion time (" + terminationTime + "ms) is longer than expected 15s", terminationTime < 15000);
-            channels.french.call(new NoopCallable()); // this only returns after the other side of the channel has finished executing cancellation
+            assertTrue(terminationTime < 15000, "Join did not finish promptly. The completion time (" + terminationTime + "ms) is longer than expected 15s");
+            french.call(new NoopCallable()); // this only returns after the other side of the channel has finished executing cancellation
             Thread.sleep(2000); // more delay to make sure it's gone
-            assertNull("process should be gone", ProcessTree.get().get(Integer.parseInt(Files.readString(tmp.toPath(), Charset.defaultCharset()).trim())));
+            assertNull(ProcessTree.get().get(Integer.parseInt(Files.readString(tmp.toPath(), Charset.defaultCharset()).trim())), "process should be gone");
 
             // Manual version of test: set up instance w/ one agent. Now in script console
             // new hudson.FilePath(new java.io.File("/tmp")).createLauncher(new hudson.util.StreamTaskListener(System.err)).
@@ -88,7 +134,8 @@ public class LauncherTest {
     }
 
     @Issue("JENKINS-15733")
-    @Test public void decorateByEnv() throws Exception {
+    @Test
+    void decorateByEnv() throws Exception {
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
         TaskListener l = new StreamBuildListener(baos, Charset.defaultCharset());
         Launcher base = new Launcher.LocalLauncher(l);
@@ -96,12 +143,13 @@ public class LauncherTest {
         Launcher decorated = base.decorateByEnv(env);
         int res = decorated.launch().envs("key2=val2").cmds(Functions.isWindows() ? new String[] {"cmd", "/q", "/c", "echo %key1% %key2%"} : new String[] {"sh", "-c", "echo $key1 $key2"}).stdout(l).join();
         String log = baos.toString(Charset.defaultCharset());
-        assertEquals(log, 0, res);
-        assertTrue(log, log.contains("val1 val2"));
+        assertEquals(0, res, log);
+        assertTrue(log.contains("val1 val2"), log);
     }
 
     @Issue("JENKINS-18368")
-    @Test public void decoratedByEnvMaintainsIsUnix() {
+    @Test
+    void decoratedByEnvMaintainsIsUnix() {
         ByteArrayOutputStream output = new ByteArrayOutputStream();
         TaskListener listener = new StreamBuildListener(output, Charset.defaultCharset());
         Launcher remoteLauncher = new Launcher.RemoteLauncher(listener, FilePath.localChannel, false);
@@ -113,7 +161,8 @@ public class LauncherTest {
     }
 
     @Issue("JENKINS-18368")
-    @Test public void decoratedByPrefixMaintainsIsUnix() {
+    @Test
+    void decoratedByPrefixMaintainsIsUnix() {
         ByteArrayOutputStream output = new ByteArrayOutputStream();
         TaskListener listener = new StreamBuildListener(output, Charset.defaultCharset());
         Launcher remoteLauncher = new Launcher.RemoteLauncher(listener, FilePath.localChannel, false);

core/src/test/java/hudson/MarkupTextTest.java

@@ -34,10 +34,10 @@ import org.junit.jupiter.api.Test;
 /**
  * @author Kohsuke Kawaguchi
  */
-public class MarkupTextTest {
+class MarkupTextTest {
 
     @Test
-    public void test1() {
+    void test1() {
         MarkupText t = new MarkupText("I fixed issue #155. The rest is trick text: xissue #155 issue #123x");
         for (SubText st : t.findTokens(pattern)) {
             assertEquals(1, st.groupCount());
@@ -48,7 +48,7 @@ public class MarkupTextTest {
     }
 
     @Test
-    public void boundary() {
+    void boundary() {
         MarkupText t = new MarkupText("issue #155---issue #123");
         for (SubText st : t.findTokens(pattern))
             st.surroundWith("<$1>", "<$1>");
@@ -57,7 +57,7 @@ public class MarkupTextTest {
     }
 
     @Test
-    public void findTokensOnSubText() {
+    void findTokensOnSubText() {
         MarkupText t = new MarkupText("Fixed 2 issues in this commit, fixing issue 155, 145");
         List<SubText> tokens = t.findTokens(Pattern.compile("issue .*"));
         assertEquals(1, tokens.size(), "Expected one token");
@@ -69,7 +69,7 @@ public class MarkupTextTest {
     }
 
     @Test
-    public void literalTextSurround() {
+    void literalTextSurround() {
         MarkupText text = new MarkupText("AAA test AAA");
         for (SubText token : text.findTokens(Pattern.compile("AAA"))) {
             token.surroundWithLiteral("$9", "$9");
@@ -81,7 +81,7 @@ public class MarkupTextTest {
      * Start/end tag nesting should be correct regardless of the order tags are added.
      */
     @Test
-    public void addMarkupInOrder() {
+    void addMarkupInOrder() {
         MarkupText text = new MarkupText("abcdef");
         text.addMarkup(0, 3, "$", "$");
         text.addMarkup(3, 6, "#", "#");
@@ -89,7 +89,7 @@ public class MarkupTextTest {
     }
 
     @Test
-    public void addMarkupInReversedOrder() {
+    void addMarkupInReversedOrder() {
         MarkupText text = new MarkupText("abcdef");
         text.addMarkup(3, 6, "#", "#");
         text.addMarkup(0, 3, "$", "$");
@@ -97,7 +97,7 @@ public class MarkupTextTest {
     }
 
     @Test
-    public void escape() {
+    void escape() {
         MarkupText text = new MarkupText("&&&");
         assertEquals("&amp;&amp;&amp;", text.toString(false));
 
@@ -107,7 +107,7 @@ public class MarkupTextTest {
     }
 
     @Test
-    public void preEscape() {
+    void preEscape() {
         MarkupText text = new MarkupText("Line\n2   & 3\n<End>\n");
         assertEquals("Line\n2   &amp; 3\n&lt;End&gt;\n", text.toString(true));
         text.addMarkup(4, "<hr/>");
@@ -116,7 +116,7 @@ public class MarkupTextTest {
 
     /* @Issue("JENKINS-6252") */
     @Test
-    public void subTextSubText() {
+    void subTextSubText() {
         MarkupText text = new MarkupText("abcdefgh");
         SubText sub = text.subText(2, 7);
         assertEquals("cdefg", sub.getText());

core/src/test/java/hudson/PluginManagerTest.java

@@ -58,12 +58,13 @@ import org.xml.sax.SAXException;
 /**
  * Tests of {@link PluginManager}.
  */
-public class PluginManagerTest {
+class PluginManagerTest {
 
-    @TempDir Path tmp;
+    @TempDir
+    private Path tmp;
 
     @Test
-    public void parseRequestedPlugins() throws Exception {
+    void parseRequestedPlugins() throws Exception {
         Path output = Files.createFile(
                 tmp.resolve("output.txt")
         );
@@ -73,17 +74,19 @@ public class PluginManagerTest {
 
     @Issue("SECURITY-167")
     @Test
-    public void parseInvalidRequestedPlugins() throws Exception {
-        String evilXML = "<?xml version='1.0' encoding='UTF-8'?>\n" +
-                "<!DOCTYPE project[<!ENTITY foo SYSTEM \"file:///\">]>\n" +
-                "<root>\n" +
-                "  <stuff plugin='stuff@1.0'>\n" +
-                "&foo;" +
-                "    <more plugin='other@2.0'>\n" +
-                "      <things plugin='stuff@1.2'/>\n" +
-                "    </more>\n" +
-                "  </stuff>\n" +
-                "</root>\n";
+    void parseInvalidRequestedPlugins() throws Exception {
+        String evilXML = """
+                <?xml version='1.0' encoding='UTF-8'?>
+                <!DOCTYPE project[<!ENTITY foo SYSTEM "file:///">]>
+                <root>
+                  <stuff plugin='stuff@1.0'>
+                &foo;\
+                    <more plugin='other@2.0'>
+                      <things plugin='stuff@1.2'/>
+                    </more>
+                  </stuff>
+                </root>
+                """;
 
         PluginManager pluginManager = new LocalPluginManager(Util.createTempDir());
         final IOException ex = assertThrows(IOException.class,
@@ -95,7 +98,7 @@ public class PluginManagerTest {
     }
 
     @Test
-    public void shouldProperlyParseManifestFromJar() throws IOException {
+    void shouldProperlyParseManifestFromJar() throws IOException {
         File jar = createHpiWithManifest();
         final Manifest manifest = PluginManager.parsePluginManifest(jar.toURI().toURL());
 
@@ -112,7 +115,7 @@ public class PluginManagerTest {
     }
 
     @Test
-    public void shouldProperlyRetrieveModificationDate() throws IOException {
+    void shouldProperlyRetrieveModificationDate() throws IOException {
         File jar = createHpiWithManifest();
         URL url = toManifestUrl(jar);
         assertThat("Manifest last modified date should be equal to the file date",
@@ -123,7 +126,7 @@ public class PluginManagerTest {
 
     @Test
     @Issue("JENKINS-70420")
-    public void updateSiteURLCheckValidation() throws Exception {
+    void updateSiteURLCheckValidation() throws Exception {
         LocalPluginManager pm = new LocalPluginManager(tmp.toFile());
 
         assertThat("ftp urls are not acceptable", pm.checkUpdateSiteURL("ftp://foo/bar"),
@@ -163,29 +166,30 @@ public class PluginManagerTest {
 
     }
 
-    private static final String SAMPLE_MANIFEST_FILE = "Manifest-Version: 1.0\n" +
-                "Archiver-Version: Plexus Archiver\n" +
-                "Created-By: Apache Maven\n" +
-                "Built-By: jglick\n" +
-                "Build-Jdk: 1.8.0_92\n" +
-                "Extension-Name: matrix-auth\n" +
-                "Specification-Title: \n" +
-                " Offers matrix-based security \n" +
-                " authorization strate\n" +
-                " gies (global and per-project).\n" +
-                "Implementation-Title: matrix-auth\n" +
-                "Implementation-Version: 1.4\n" +
-                "Group-Id: org.jenkins-ci.plugins\n" +
-                "Short-Name: matrix-auth\n" +
-                "Long-Name: Matrix Authorization Strategy Plugin\n" +
-                "Url: http://wiki.jenkins-ci.org/display/JENKINS/Matrix+Authorization+S\n" +
-                " trategy+Plugin\n" +
-                "Plugin-Version: 1.4\n" +
-                "Hudson-Version: 1.609.1\n" +
-                "Jenkins-Version: 1.609.1\n" +
-                "Plugin-Dependencies: icon-shim:2.0.3,cloudbees-folder:5.2.2;resolution\n" +
-                " :=optional\n" +
-                "Plugin-Developers: ";
+    private static final String SAMPLE_MANIFEST_FILE = """
+            Manifest-Version: 1.0
+            Archiver-Version: Plexus Archiver
+            Created-By: Apache Maven
+            Built-By: jglick
+            Build-Jdk: 1.8.0_92
+            Extension-Name: matrix-auth
+            Specification-Title:\s
+             Offers matrix-based security\s
+             authorization strate
+             gies (global and per-project).
+            Implementation-Title: matrix-auth
+            Implementation-Version: 1.4
+            Group-Id: org.jenkins-ci.plugins
+            Short-Name: matrix-auth
+            Long-Name: Matrix Authorization Strategy Plugin
+            Url: http://wiki.jenkins-ci.org/display/JENKINS/Matrix+Authorization+S
+             trategy+Plugin
+            Plugin-Version: 1.4
+            Hudson-Version: 1.609.1
+            Jenkins-Version: 1.609.1
+            Plugin-Dependencies: icon-shim:2.0.3,cloudbees-folder:5.2.2;resolution
+             :=optional
+            Plugin-Developers:\s""";
 
     private File createHpiWithManifest() throws IOException {
         Path metaInf = tmp.resolve("META-INF");

core/src/test/java/hudson/PluginWrapperTest.java

@@ -32,26 +32,26 @@ import org.junit.jupiter.api.Test;
 import org.jvnet.hudson.test.Issue;
 import org.mockito.stubbing.Answer;
 
-public class PluginWrapperTest {
+class PluginWrapperTest {
 
     private static Locale loc;
 
     @BeforeAll
-    public static void before() {
+    static void before() {
         Jenkins.VERSION = "2.0"; // Some value needed - tests will overwrite if necessary
         loc = Locale.getDefault();
         Locale.setDefault(new Locale("en", "GB"));
     }
 
     @AfterAll
-    public static void after() {
+    static void after() {
         if (loc != null) {
             Locale.setDefault(loc);
         }
     }
 
     @Test
-    public void dependencyTest() {
+    void dependencyTest() {
         String version = "plugin:0.0.2";
         PluginWrapper.Dependency dependency = new PluginWrapper.Dependency(version);
         assertEquals("plugin", dependency.shortName);
@@ -60,7 +60,7 @@ public class PluginWrapperTest {
     }
 
     @Test
-    public void optionalDependencyTest() {
+    void optionalDependencyTest() {
         String version = "plugin:0.0.2;resolution:=optional";
         PluginWrapper.Dependency dependency = new PluginWrapper.Dependency(version);
         assertEquals("plugin", dependency.shortName);
@@ -69,7 +69,7 @@ public class PluginWrapperTest {
     }
 
     @Test
-    public void jenkinsCoreTooOld() {
+    void jenkinsCoreTooOld() {
         PluginWrapper pw = pluginWrapper("fake").requiredCoreVersion("3.0").buildLoaded();
 
         final IOException ex = assertThrows(IOException.class, pw::resolvePluginDependencies);
@@ -77,7 +77,7 @@ public class PluginWrapperTest {
     }
 
     @Test
-    public void dependencyNotInstalled() {
+    void dependencyNotInstalled() {
         PluginWrapper pw = pluginWrapper("dependee").deps("dependency:42").buildLoaded();
 
         final IOException ex = assertThrows(IOException.class, pw::resolvePluginDependencies);
@@ -85,7 +85,7 @@ public class PluginWrapperTest {
     }
 
     @Test
-    public void dependencyOutdated() {
+    void dependencyOutdated() {
         pluginWrapper("dependency").version("3").buildLoaded();
         PluginWrapper pw = pluginWrapper("dependee").deps("dependency:5").buildLoaded();
 
@@ -94,7 +94,7 @@ public class PluginWrapperTest {
     }
 
     @Test
-    public void dependencyFailedToLoad() {
+    void dependencyFailedToLoad() {
         pluginWrapper("dependency").version("5").buildFailed();
         PluginWrapper pw = pluginWrapper("dependee").deps("dependency:3").buildLoaded();
 
@@ -104,7 +104,7 @@ public class PluginWrapperTest {
 
     @Issue("JENKINS-66563")
     @Test
-    public void insertJarsIntoClassPath() throws Exception {
+    void insertJarsIntoClassPath() throws Exception {
         try (URLClassLoader2 cl = new URLClassLoader2("Test", new URL[0])) {
             assertInjectingJarsWorks(cl);
         }
@@ -210,7 +210,7 @@ public class PluginWrapperTest {
 
     @Issue("JENKINS-52665")
     @Test
-    public void isSnapshot() {
+    void isSnapshot() {
         assertFalse(PluginWrapper.isSnapshot("1.0"));
         assertFalse(PluginWrapper.isSnapshot("1.0-alpha-1"));
         assertFalse(PluginWrapper.isSnapshot("1.0-rc9999.abc123def456"));

core/src/test/java/hudson/ProxyConfigurationTest.java

@@ -29,10 +29,10 @@ import static org.junit.jupiter.api.Assertions.assertEquals;
 import java.net.Proxy;
 import org.junit.jupiter.api.Test;
 
-public class ProxyConfigurationTest {
+class ProxyConfigurationTest {
 
     @Test
-    public void noProxyHost() {
+    void noProxyHost() {
         String noProxyHost = "*.example.com|192.168.*";
         assertEquals(Proxy.Type.HTTP, ProxyConfiguration.createProxy("test.example.co.jp", "proxy.example.com", 8080, noProxyHost).type());
         assertEquals(Proxy.Type.DIRECT, ProxyConfiguration.createProxy("test.example.com", "proxy.example.com", 8080, noProxyHost).type());

core/src/test/java/hudson/RemoveWindowsDirectoryJunctionTest.java

@@ -4,40 +4,50 @@
 
 package hudson;
 
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assume.assumeTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
 
 import hudson.os.WindowsUtil;
 import java.io.File;
-import org.junit.Before;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import java.io.IOException;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.jvnet.hudson.test.For;
 import org.jvnet.hudson.test.Issue;
 
 @For(Util.class)
 // https://superuser.com/q/343074
-public class RemoveWindowsDirectoryJunctionTest {
-    @Rule
-    public TemporaryFolder tmp = new TemporaryFolder();
+class RemoveWindowsDirectoryJunctionTest {
 
-    @Before
-    public void windowsOnly() {
+    @TempDir
+    private File tmp;
+
+    @BeforeEach
+    void windowsOnly() {
        assumeTrue(Functions.isWindows());
     }
 
     @Test
     @Issue("JENKINS-2995")
-    public void testJunctionIsRemovedButNotContents() throws Exception {
-        File subdir1 = tmp.newFolder("notJunction");
+    void testJunctionIsRemovedButNotContents() throws Exception {
+        File subdir1 = newFolder(tmp, "notJunction");
         File f1 = new File(subdir1, "testfile1.txt");
-        assertTrue("Unable to create temporary file in notJunction directory", f1.createNewFile());
-        File j1 = WindowsUtil.createJunction(new File(tmp.getRoot(), "test junction"), subdir1);
+        assertTrue(f1.createNewFile(), "Unable to create temporary file in notJunction directory");
+        File j1 = WindowsUtil.createJunction(new File(tmp, "test junction"), subdir1);
         Util.deleteRecursive(j1);
-        assertFalse("Windows Junction should have been removed", j1.exists());
-        assertTrue("Contents of Windows Junction should not be removed", f1.exists());
+        assertFalse(j1.exists(), "Windows Junction should have been removed");
+        assertTrue(f1.exists(), "Contents of Windows Junction should not be removed");
+    }
+
+    private static File newFolder(File root, String... subDirs) throws IOException {
+        String subFolder = String.join("/", subDirs);
+        File result = new File(root, subFolder);
+        if (!result.mkdirs()) {
+            throw new IOException("Couldn't create folders " + root);
+        }
+        return result;
     }
 
 }

core/src/test/java/hudson/UtilTest.java

@@ -28,16 +28,16 @@ package hudson;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.not;
 import static org.hamcrest.Matchers.startsWith;
-import static org.junit.Assert.assertArrayEquals;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
-import static org.junit.Assume.assumeFalse;
-import static org.junit.Assume.assumeNoException;
-import static org.junit.Assume.assumeTrue;
+import static org.junit.jupiter.api.Assertions.assertArrayEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
+import static org.junit.jupiter.api.Assumptions.assumeFalse;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
 
 import hudson.model.TaskListener;
 import hudson.os.WindowsUtil;
@@ -62,21 +62,20 @@ import java.util.Properties;
 import org.apache.commons.io.FileUtils;
 import org.hamcrest.BaseMatcher;
 import org.hamcrest.Description;
-import org.junit.Assert;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.jvnet.hudson.test.Issue;
 
 /**
  * @author Kohsuke Kawaguchi
  */
-public class UtilTest {
+class UtilTest {
 
-    @Rule public TemporaryFolder tmp = new TemporaryFolder();
+    @TempDir
+    private File tmp;
 
     @Test
-    public void testReplaceMacro() {
+    void testReplaceMacro() {
         Map<String, String> m = new HashMap<>();
         m.put("A", "a");
         m.put("A.B", "a-b");
@@ -111,7 +110,7 @@ public class UtilTest {
     }
 
     @Test
-    public void testTimeSpanString() {
+    void testTimeSpanString() {
         // Check that amounts less than 365 days are not rounded up to a whole year.
         // In the previous implementation there were 360 days in a year.
         // We're still working on the assumption that a month is 30 days, so there will
@@ -144,8 +143,8 @@ public class UtilTest {
         Locale.setDefault(Locale.GERMANY);
         try {
             // Just verifying no exception is thrown:
-            assertNotNull("German locale", Util.getTimeSpanString(1234));
-            assertNotNull("German locale <1 sec", Util.getTimeSpanString(123));
+            assertNotNull(Util.getTimeSpanString(1234), "German locale");
+            assertNotNull(Util.getTimeSpanString(123), "German locale <1 sec");
         }
         finally { Locale.setDefault(saveLocale); }
     }
@@ -155,7 +154,7 @@ public class UtilTest {
      * Test that Strings that contain spaces are correctly URL encoded.
      */
     @Test
-    public void testEncodeSpaces() {
+    void testEncodeSpaces() {
         final String urlWithSpaces = "http://hudson/job/Hudson Job";
         String encoded = Util.encode(urlWithSpaces);
         assertEquals("http://hudson/job/Hudson%20Job", encoded);
@@ -165,7 +164,7 @@ public class UtilTest {
      * Test the rawEncode() method.
      */
     @Test
-    public void testRawEncode() {
+    void testRawEncode() {
         String[] data = {  // Alternating raw,encoded
             "abcdefghijklmnopqrstuvwxyz",
             "abcdefghijklmnopqrstuvwxyz",
@@ -185,7 +184,7 @@ public class UtilTest {
             "%C3%A9%20",
         };
         for (int i = 0; i < data.length; i += 2) {
-            assertEquals("test " + i, data[i + 1], Util.rawEncode(data[i]));
+            assertEquals(data[i + 1], Util.rawEncode(data[i]), "test " + i);
         }
     }
 
@@ -193,7 +192,7 @@ public class UtilTest {
      * Test the fullEncode() method.
      */
     @Test
-    public void testFullEncode() {
+    void testFullEncode() {
         String[] data = {
                 "abcdefghijklmnopqrstuvwxyz",
                 "abcdefghijklmnopqrstuvwxyz",
@@ -213,7 +212,7 @@ public class UtilTest {
                 "%C3%A9%20",
         };
         for (int i = 0; i < data.length; i += 2) {
-            assertEquals("test " + i, data[i + 1], Util.fullEncode(data[i]));
+            assertEquals(data[i + 1], Util.fullEncode(data[i]), "test " + i);
         }
     }
 
@@ -221,20 +220,20 @@ public class UtilTest {
      * Test the tryParseNumber() method.
      */
     @Test
-    public void testTryParseNumber() {
-        assertEquals("Successful parse did not return the parsed value", 20, Util.tryParseNumber("20", 10).intValue());
-        assertEquals("Failed parse did not return the default value", 10, Util.tryParseNumber("ss", 10).intValue());
-        assertEquals("Parsing empty string did not return the default value", 10, Util.tryParseNumber("", 10).intValue());
-        assertEquals("Parsing null string did not return the default value", 10, Util.tryParseNumber(null, 10).intValue());
+    void testTryParseNumber() {
+        assertEquals(20, Util.tryParseNumber("20", 10).intValue(), "Successful parse did not return the parsed value");
+        assertEquals(10, Util.tryParseNumber("ss", 10).intValue(), "Failed parse did not return the default value");
+        assertEquals(10, Util.tryParseNumber("", 10).intValue(), "Parsing empty string did not return the default value");
+        assertEquals(10, Util.tryParseNumber(null, 10).intValue(), "Parsing null string did not return the default value");
     }
 
     @Test
-    public void testSymlink() throws Exception {
+    void testSymlink() throws Exception {
         assumeFalse(Functions.isWindows());
 
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
         StreamTaskListener l = new StreamTaskListener(baos, Charset.defaultCharset());
-        File d = tmp.getRoot();
+        File d = tmp;
         try {
             new FilePath(new File(d, "a")).touch(0);
             assertNull(Util.resolveSymlink(new File(d, "a")));
@@ -256,7 +255,7 @@ public class UtilTest {
 
             // test linking from another directory
             File anotherDir = new File(d, "anotherDir");
-            assertTrue("Couldn't create " + anotherDir, anotherDir.mkdir());
+            assertTrue(anotherDir.mkdir(), "Couldn't create " + anotherDir);
 
             Util.createSymlink(d, "a", "anotherDir/link", l);
             assertEquals("a", Util.resolveSymlink(new File(d, "anotherDir/link")));
@@ -277,12 +276,12 @@ public class UtilTest {
     }
 
     @Test
-    public void testIsSymlink() throws IOException, InterruptedException {
+    void testIsSymlink() throws IOException, InterruptedException {
         assumeFalse(Functions.isWindows());
 
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
         StreamTaskListener l = new StreamTaskListener(baos, Charset.defaultCharset());
-        File d = tmp.getRoot();
+        File d = tmp;
         try {
             new FilePath(new File(d, "original")).touch(0);
             assertFalse(Util.isSymlink(new File(d, "original")));
@@ -292,11 +291,11 @@ public class UtilTest {
 
             // test linking to another directory
             File dir = new File(d, "dir");
-            assertTrue("Couldn't create " + dir, dir.mkdir());
+            assertTrue(dir.mkdir(), "Couldn't create " + dir);
             assertFalse(Util.isSymlink(new File(d, "dir")));
 
             File anotherDir = new File(d, "anotherDir");
-            assertTrue("Couldn't create " + anotherDir, anotherDir.mkdir());
+            assertTrue(anotherDir.mkdir(), "Couldn't create " + anotherDir);
 
             Util.createSymlink(d, "dir", "anotherDir/symlinkDir", l);
             // JENKINS-12331: either a bug in createSymlink or this isn't supposed to work:
@@ -307,22 +306,22 @@ public class UtilTest {
     }
 
     @Test
-    public void testIsSymlink_onWindows_junction() throws Exception {
-        assumeTrue("Uses Windows-specific features", Functions.isWindows());
-        File targetDir = tmp.newFolder("targetDir");
-        File d = tmp.newFolder("dir");
+    void testIsSymlink_onWindows_junction() throws Exception {
+        assumeTrue(Functions.isWindows(), "Uses Windows-specific features");
+        File targetDir = newFolder(tmp, "targetDir");
+        File d = newFolder(tmp, "dir");
         File junction = WindowsUtil.createJunction(new File(d, "junction"), targetDir);
         assertTrue(Util.isSymlink(junction));
     }
 
     @Test
     @Issue("JENKINS-55448")
-    public void testIsSymlink_ParentIsJunction() throws IOException, InterruptedException {
-        assumeTrue("Uses Windows-specific features", Functions.isWindows());
-        File targetDir = tmp.newFolder();
+    void testIsSymlink_ParentIsJunction() throws IOException, InterruptedException {
+        assumeTrue(Functions.isWindows(), "Uses Windows-specific features");
+        File targetDir = newFolder(tmp, "junit");
         File file = new File(targetDir, "test-file");
         new FilePath(file).touch(System.currentTimeMillis());
-        File dir = tmp.newFolder();
+        File dir = newFolder(tmp, "junit");
         File junction = WindowsUtil.createJunction(new File(dir, "junction"), targetDir);
 
         assertTrue(Util.isSymlink(junction));
@@ -331,19 +330,19 @@ public class UtilTest {
 
     @Test
     @Issue("JENKINS-55448")
-    public void testIsSymlink_ParentIsSymlink() throws IOException, InterruptedException {
+    void testIsSymlink_ParentIsSymlink() throws IOException, InterruptedException {
         assumeFalse(Functions.isWindows());
-        File folder = tmp.newFolder();
+        File folder = newFolder(tmp, "junit");
         File file = new File(folder, "test-file");
         new FilePath(file).touch(System.currentTimeMillis());
-        Path link = tmp.getRoot().toPath().resolve("sym-link");
+        Path link = tmp.toPath().resolve("sym-link");
         Path pathWithSymlinkParent = Files.createSymbolicLink(link, folder.toPath()).resolve("test-file");
         assertTrue(Util.isSymlink(link));
         assertFalse(Util.isSymlink(pathWithSymlinkParent));
     }
 
     @Test
-    public void testHtmlEscape() {
+    void testHtmlEscape() {
         assertEquals("<br>", Util.escape("\n"));
         assertEquals("&lt;a&gt;", Util.escape("<a>"));
         assertEquals("&#039;&quot;", Util.escape("'\""));
@@ -356,7 +355,7 @@ public class UtilTest {
      */
     @Issue("JENKINS-10346")
     @Test
-    public void testDigestThreadSafety() throws InterruptedException {
+    void testDigestThreadSafety() throws InterruptedException {
         String a = "abcdefgh";
         String b = "123456789";
 
@@ -405,7 +404,7 @@ public class UtilTest {
 
     @Test
     @SuppressWarnings("deprecation")
-    public void testIsAbsoluteUri() {
+    void testIsAbsoluteUri() {
         assertTrue(Util.isAbsoluteUri("http://foobar/"));
         assertTrue(Util.isAbsoluteUri("mailto:kk@kohsuke.org"));
         assertTrue(Util.isAbsoluteUri("d123://test/"));
@@ -417,7 +416,7 @@ public class UtilTest {
 
     @Test
     @Issue({"SECURITY-276", "SECURITY-3501"})
-    public void testIsSafeToRedirectTo() {
+    void testIsSafeToRedirectTo() {
         assertFalse(Util.isSafeToRedirectTo("http://foobar/"));
         assertFalse(Util.isSafeToRedirectTo("mailto:kk@kohsuke.org"));
         assertFalse(Util.isSafeToRedirectTo("d123://test/"));
@@ -440,7 +439,7 @@ public class UtilTest {
     }
 
     @Test
-    public void loadFile() throws IOException {
+    void loadFile() throws IOException {
         // Standard character sets
         assertEquals(
                 "Iñtërnâtiônàlizætiøn",
@@ -473,17 +472,17 @@ public class UtilTest {
     }
 
     @Test
-    public void loadProperties() throws IOException {
+    void loadProperties() throws IOException {
 
         assertEquals(0, Util.loadProperties("").size());
 
         Properties p = Util.loadProperties("k.e.y=va.l.ue");
-        assertEquals(p.toString(), "va.l.ue", p.get("k.e.y"));
-        assertEquals(p.toString(), 1, p.size());
+        assertEquals("va.l.ue", p.get("k.e.y"), p.toString());
+        assertEquals(1, p.size(), p.toString());
     }
 
     @Test
-    public void isRelativePathUnix() {
+    void isRelativePathUnix() {
         assertThat("/", not(aRelativePath()));
         assertThat("/foo/bar", not(aRelativePath()));
         assertThat("/foo/../bar", not(aRelativePath()));
@@ -496,7 +495,7 @@ public class UtilTest {
     }
 
     @Test
-    public void isRelativePathWindows() {
+    void isRelativePathWindows() {
         assertThat("\\", aRelativePath());
         assertThat("\\foo\\bar", aRelativePath());
         assertThat("\\foo\\..\\bar", aRelativePath());
@@ -534,7 +533,7 @@ public class UtilTest {
     }
 
     @Test
-    public void testIsDescendant() throws IOException {
+    void testIsDescendant() throws IOException {
         File root;
         File other;
         if (Functions.isWindows()) {
@@ -572,7 +571,7 @@ public class UtilTest {
     }
 
     @Test
-    public void testModeToPermissions() throws Exception {
+    void testModeToPermissions() throws Exception {
         assertEquals(PosixFilePermissions.fromString("rwxrwxrwx"), Util.modeToPermissions(0777));
         assertEquals(PosixFilePermissions.fromString("rwxr-xrwx"), Util.modeToPermissions(0757));
         assertEquals(PosixFilePermissions.fromString("rwxr-x---"), Util.modeToPermissions(0750));
@@ -584,14 +583,14 @@ public class UtilTest {
         assertEquals(PosixFilePermissions.fromString("-wxr--rw-"), Util.modeToPermissions(0346));
         assertEquals(PosixFilePermissions.fromString("---------"), Util.modeToPermissions(0000));
 
-        assertEquals("Non-permission bits should be ignored", PosixFilePermissions.fromString("r-xr-----"), Util.modeToPermissions(0100540));
+        assertEquals(PosixFilePermissions.fromString("r-xr-----"), Util.modeToPermissions(0100540), "Non-permission bits should be ignored");
 
-        Exception e = Assert.assertThrows(Exception.class, () -> Util.modeToPermissions(01777));
+        Exception e = assertThrows(Exception.class, () -> Util.modeToPermissions(01777));
         assertThat(e.getMessage(), startsWith("Invalid mode"));
     }
 
     @Test
-    public void testPermissionsToMode() {
+    void testPermissionsToMode() {
         assertEquals(0777, Util.permissionsToMode(PosixFilePermissions.fromString("rwxrwxrwx")));
         assertEquals(0757, Util.permissionsToMode(PosixFilePermissions.fromString("rwxr-xrwx")));
         assertEquals(0750, Util.permissionsToMode(PosixFilePermissions.fromString("rwxr-x---")));
@@ -605,7 +604,7 @@ public class UtilTest {
     }
 
     @Test
-    public void testDifferenceDays() throws Exception {
+    void testDifferenceDays() throws Exception {
         Date may_6_10am = parseDate("2018-05-06 10:00:00");
         Date may_6_11pm55 = parseDate("2018-05-06 23:55:00");
         Date may_7_01am = parseDate("2018-05-07 01:00:00");
@@ -636,7 +635,7 @@ public class UtilTest {
 
     @Test
     @Issue("SECURITY-904")
-    public void resolveSymlinkToFile() throws Exception {
+    void resolveSymlinkToFile() throws Exception {
         assumeFalse(Functions.isWindows());
         //  root
         //      /a
@@ -645,7 +644,7 @@ public class UtilTest {
         //          /_b => symlink to /root/b
         //      /b
         //          /_a => symlink to /root/a
-        File root = tmp.getRoot();
+        File root = tmp;
         File a = new File(root, "a");
         File aa = new File(a, "aa");
         aa.mkdirs();
@@ -675,14 +674,14 @@ public class UtilTest {
 
     @Test
     @Issue("JENKINS-67372")
-    public void createDirectories() throws Exception {
+    void createDirectories() throws Exception {
         assumeFalse(Functions.isWindows());
         //  root
         //      /a
         //          /a1
         //          /a2 => symlink to a1
         //      /b => symlink to a
-        Path root = tmp.getRoot().toPath().toRealPath();
+        Path root = tmp.toPath().toRealPath();
         Path a = root.resolve("a");
         Path a1 = a.resolve("a1");
         Files.createDirectories(a1);
@@ -706,7 +705,7 @@ public class UtilTest {
 
     @Test
     @Issue("JENKINS-67372")
-    public void createDirectoriesInRoot() throws Exception {
+    void createDirectoriesInRoot() throws Exception {
         assumeFalse(Functions.isWindows());
         Path newDirInRoot = Paths.get("/new-dir-in-root");
         Path newSymlinkInRoot = Paths.get("/new-symlink-in-root");
@@ -716,30 +715,30 @@ public class UtilTest {
             assertEquals(newDirInRoot.resolve("new2"), Util.createDirectories(newSymlinkInRoot.resolve("new2")).toRealPath());
         } catch (FileSystemException e) {
             // Not running as root
-            assumeNoException(e);
+            assumeTrue(false, e.toString());
         }
     }
 
     @Test
-    public void ifOverriddenSuccess() {
+    void ifOverriddenSuccess() {
         assertTrue(Util.ifOverridden(() -> true, BaseClass.class, DerivedClassSuccess.class, "method"));
     }
 
     @Test
-    public void ifOverriddenFailure() {
-        AbstractMethodError error = Assert.assertThrows(AbstractMethodError.class, () -> Util.ifOverridden(() -> true, BaseClass.class, DerivedClassFailure.class, "method"));
+    void ifOverriddenFailure() {
+        AbstractMethodError error = assertThrows(AbstractMethodError.class, () -> Util.ifOverridden(() -> true, BaseClass.class, DerivedClassFailure.class, "method"));
         assertEquals("The class " + DerivedClassFailure.class.getName() + " must override at least one of the BaseClass.method methods", error.getMessage());
     }
 
     @Test
-    public void testGetHexOfSHA256DigestOf() throws IOException {
+    void testGetHexOfSHA256DigestOf() {
         byte[] input = new byte[] {12, 34, 16};
         String str = Util.getHexOfSHA256DigestOf(input);
-        assertEquals(str, "134fefbd329986726407a5208107ef07c9e33da779f5068bff191733268fe997");
+        assertEquals("134fefbd329986726407a5208107ef07c9e33da779f5068bff191733268fe997", str);
     }
 
     @Test
-    public void testGetSHA256DigestOf() {
+    void testGetSHA256DigestOf() {
         byte[] input = new byte[] {12, 34, 16};
         byte[] sha256DigestActual = Util.getSHA256DigestOf(input);
 
@@ -753,6 +752,7 @@ public class UtilTest {
         protected String method() {
             return "base";
         }
+
     }
 
     public static class DerivedClassFailure extends BaseClass {
@@ -764,5 +764,15 @@ public class UtilTest {
         protected String method() {
             return DerivedClassSuccess.class.getName();
         }
+
+    }
+
+    private static File newFolder(File root, String... subDirs) throws IOException {
+        String subFolder = String.join("/", subDirs);
+        File result = new File(root, subFolder);
+        if (!result.exists() && !result.mkdirs()) {
+            throw new IOException("Couldn't create folders " + root);
+        }
+        return result;
     }
 }

core/src/test/java/hudson/XmlFileTest.java

@@ -3,7 +3,7 @@ package hudson;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import com.thoughtworks.xstream.converters.ConversionException;
 import com.thoughtworks.xstream.io.StreamException;
@@ -14,12 +14,12 @@ import java.io.File;
 import java.io.IOException;
 import java.net.URL;
 import jenkins.model.Jenkins;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-public class XmlFileTest {
+class XmlFileTest {
 
     @Test
-    public void canReadXml1_0Test() throws IOException {
+    void canReadXml1_0Test() throws IOException {
         URL configUrl = getClass().getResource("/hudson/config_1_0.xml");
         XStream2  xs = new XStream2();
         xs.alias("hudson", Jenkins.class);
@@ -33,7 +33,7 @@ public class XmlFileTest {
     }
 
     @Test
-    public void xml1_0_withSpecialCharsShouldFail() {
+    void xml1_0_withSpecialCharsShouldFail() {
         URL configUrl = getClass().getResource("/hudson/config_1_0_with_special_chars.xml");
         XStream2  xs = new XStream2();
         xs.alias("hudson", Jenkins.class);
@@ -53,7 +53,7 @@ public class XmlFileTest {
     }
 
     @Test
-    public void canReadXml1_1Test() throws IOException {
+    void canReadXml1_1Test() throws IOException {
         URL configUrl = getClass().getResource("/hudson/config_1_1.xml");
         XStream2  xs = new XStream2();
         xs.alias("hudson", Jenkins.class);
@@ -67,7 +67,7 @@ public class XmlFileTest {
     }
 
     @Test
-    public void canReadXmlWithControlCharsTest() throws IOException {
+    void canReadXmlWithControlCharsTest() throws IOException {
         URL configUrl = getClass().getResource("/hudson/config_1_1_with_special_chars.xml");
         XStream2  xs = new XStream2();
         xs.alias("hudson", Jenkins.class);

core/src/test/java/hudson/util/ArgumentListBuilderTest.java

@@ -27,88 +27,88 @@ package hudson.util;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.LinkedHashMap;
 import java.util.Map;
 import java.util.Set;
-import org.junit.Ignore;
-import org.junit.Test;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
 import org.jvnet.hudson.test.Issue;
 
-public class ArgumentListBuilderTest {
+class ArgumentListBuilderTest {
 
     @Test
-    public void assertEmptyMask() {
+    void assertEmptyMask() {
         ArgumentListBuilder builder = new ArgumentListBuilder();
         builder.add("arg");
         builder.add("other", "arguments");
 
-        assertFalse("There should not be any masked arguments", builder.hasMaskedArguments());
+        assertFalse(builder.hasMaskedArguments(), "There should not be any masked arguments");
         boolean[] array = builder.toMaskArray();
-        assertNotNull("The mask array should not be null", array);
+        assertNotNull(array, "The mask array should not be null");
         assertThat("The mask array was incorrect", array, is(new boolean[] { false, false, false }));
     }
 
     @Test
-    public void assertLastArgumentIsMasked() {
+    void assertLastArgumentIsMasked() {
         ArgumentListBuilder builder = new ArgumentListBuilder();
         builder.add("arg");
         builder.addMasked("ismasked");
 
-        assertTrue("There should be masked arguments", builder.hasMaskedArguments());
+        assertTrue(builder.hasMaskedArguments(), "There should be masked arguments");
         boolean[] array = builder.toMaskArray();
-        assertNotNull("The mask array should not be null", array);
+        assertNotNull(array, "The mask array should not be null");
         assertThat("The mask array was incorrect", array, is(new boolean[] { false, true }));
     }
 
     @Test
-    public void assertSeveralMaskedArguments() {
+    void assertSeveralMaskedArguments() {
         ArgumentListBuilder builder = new ArgumentListBuilder();
         builder.add("arg");
         builder.addMasked("ismasked");
         builder.add("non masked arg");
         builder.addMasked("ismasked2");
 
-        assertTrue("There should be masked arguments", builder.hasMaskedArguments());
+        assertTrue(builder.hasMaskedArguments(), "There should be masked arguments");
         boolean[] array = builder.toMaskArray();
-        assertNotNull("The mask array should not be null", array);
+        assertNotNull(array, "The mask array should not be null");
         assertThat("The mask array was incorrect", array, is(new boolean[] { false, true, false, true }));
     }
 
     @Test
-    public void assertPrependAfterAddingMasked() {
+    void assertPrependAfterAddingMasked() {
         ArgumentListBuilder builder = new ArgumentListBuilder();
         builder.addMasked("ismasked");
         builder.add("arg");
         builder.prepend("first", "second");
 
-        assertTrue("There should be masked arguments", builder.hasMaskedArguments());
+        assertTrue(builder.hasMaskedArguments(), "There should be masked arguments");
         boolean[] array = builder.toMaskArray();
-        assertNotNull("The mask array should not be null", array);
+        assertNotNull(array, "The mask array should not be null");
         assertThat("The mask array was incorrect", array, is(new boolean[] { false, false, true, false }));
     }
 
     @Test
-    public void assertPrependBeforeAddingMasked() {
+    void assertPrependBeforeAddingMasked() {
         ArgumentListBuilder builder = new ArgumentListBuilder();
         builder.prepend("first", "second");
         builder.addMasked("ismasked");
         builder.add("arg");
 
-        assertTrue("There should be masked arguments", builder.hasMaskedArguments());
+        assertTrue(builder.hasMaskedArguments(), "There should be masked arguments");
         boolean[] array = builder.toMaskArray();
-        assertNotNull("The mask array should not be null", array);
+        assertNotNull(array, "The mask array should not be null");
         assertThat("The mask array was incorrect", array, is(new boolean[] { false, false, true, false }));
     }
 
     @Test
-    public void testToWindowsCommand() {
+    void testToWindowsCommand() {
         ArgumentListBuilder builder = new ArgumentListBuilder().
                 add("ant.bat").add("-Dfoo1=abc").  // nothing special, no quotes
                 add("-Dfoo2=foo bar").add("-Dfoo3=/u*r").add("-Dfoo4=/us?").  // add quotes
@@ -148,9 +148,9 @@ public class ArgumentListBuilderTest {
     }
 
     @Test
-    @Ignore("It's only for reproduce JENKINS-28790 issue. It's added to testToWindowsCommand")
+    @Disabled("It's only for reproduce JENKINS-28790 issue. It's added to testToWindowsCommand")
     @Issue("JENKINS-28790")
-    public void testToWindowsCommandMasked() {
+    void testToWindowsCommandMasked() {
         ArgumentListBuilder builder = new ArgumentListBuilder().
                 add("ant.bat").add("-Dfoo1=abc").  // nothing special, no quotes
                 add("-Dfoo2=foo bar").add("-Dfoo3=/u*r").add("-Dfoo4=/us?").  // add quotes
@@ -177,16 +177,16 @@ public class ArgumentListBuilderTest {
     }
 
     @Test
-    public void assertMaskOnClone() {
+    void assertMaskOnClone() {
         ArgumentListBuilder builder = new ArgumentListBuilder();
         builder.add("arg1");
         builder.addMasked("masked1");
         builder.add("arg2");
 
         ArgumentListBuilder clone = builder.clone();
-        assertTrue("There should be masked arguments", clone.hasMaskedArguments());
+        assertTrue(clone.hasMaskedArguments(), "There should be masked arguments");
         boolean[] array = clone.toMaskArray();
-        assertNotNull("The mask array should not be null", array);
+        assertNotNull(array, "The mask array should not be null");
         assertThat("The mask array was incorrect", array, is(builder.toMaskArray()));
     }
 
@@ -201,30 +201,30 @@ public class ArgumentListBuilderTest {
     private static final Set<String> MASKS = Set.of("key2");
 
     @Test
-    public void assertKeyValuePairsWithMask() {
+    void assertKeyValuePairsWithMask() {
         ArgumentListBuilder builder = new ArgumentListBuilder();
         builder.addKeyValuePairs(null, KEY_VALUES, MASKS);
 
-        assertTrue("There should be masked arguments", builder.hasMaskedArguments());
+        assertTrue(builder.hasMaskedArguments(), "There should be masked arguments");
         boolean[] array = builder.toMaskArray();
-        assertNotNull("The mask array should not be null", array);
+        assertNotNull(array, "The mask array should not be null");
         assertThat("The mask array was incorrect", array, is(new boolean[] { false, true, false }));
 
     }
 
     @Test
-    public void assertKeyValuePairs() {
+    void assertKeyValuePairs() {
         ArgumentListBuilder builder = new ArgumentListBuilder();
         builder.addKeyValuePairs(null, KEY_VALUES);
 
-        assertFalse("There should not be any masked arguments", builder.hasMaskedArguments());
+        assertFalse(builder.hasMaskedArguments(), "There should not be any masked arguments");
         boolean[] array = builder.toMaskArray();
-        assertNotNull("The mask array should not be null", array);
+        assertNotNull(array, "The mask array should not be null");
         assertThat("The mask array was incorrect", array, is(new boolean[] { false, false, false }));
     }
 
     @Test
-    public void addKeyValuePairsFromPropertyString() throws IOException {
+    void addKeyValuePairsFromPropertyString() throws IOException {
         final Map<String, String> map = new HashMap<>();
         map.put("PATH", "C:\\Windows");
         final VariableResolver<String> resolver = new VariableResolver.ByMap<>(map);
@@ -241,15 +241,17 @@ public class ArgumentListBuilderTest {
     }
 
     @Test
-    public void numberOfBackslashesInPropertiesShouldBePreservedAfterMacroExpansion() throws IOException {
+    void numberOfBackslashesInPropertiesShouldBePreservedAfterMacroExpansion() throws IOException {
         final Map<String, String> map = new HashMap<>();
         map.put("ONE", "one\\backslash");
         map.put("TWO", "two\\\\backslashes");
         map.put("FOUR", "four\\\\\\\\backslashes");
 
-        final String properties = "one=$ONE\n" +
-                "two=$TWO\n" +
-                "four=$FOUR\n"
+        final String properties = """
+                one=$ONE
+                two=$TWO
+                four=$FOUR
+                """
         ;
 
         final String args = new ArgumentListBuilder()

core/src/test/java/hudson/util/AtomicFileWriterTest.java

@@ -4,12 +4,12 @@ import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assume.assumeFalse;
-import static org.junit.Assume.assumeThat;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assumptions.assumeFalse;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
 
 import edu.umd.cs.findbugs.annotations.Nullable;
 import hudson.Functions;
@@ -22,15 +22,14 @@ import java.nio.file.Path;
 import java.nio.file.Paths;
 import java.nio.file.attribute.PosixFilePermission;
 import java.util.Set;
-import org.junit.After;
-import org.junit.Before;
-import org.junit.BeforeClass;
-import org.junit.ClassRule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeAll;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.jvnet.hudson.test.Issue;
 
-public class AtomicFileWriterTest {
+class AtomicFileWriterTest {
     private static final String PREVIOUS = "previous value \n blah";
     /**
      * Provides access to the default permissions given to a new file. (i.e. indirect way to get umask settings).
@@ -38,15 +37,15 @@ public class AtomicFileWriterTest {
      */
     @Nullable
     private static Set<PosixFilePermission> DEFAULT_GIVEN_PERMISSIONS;
-    @ClassRule
-    public static TemporaryFolder tmp = new TemporaryFolder();
-    File af;
-    AtomicFileWriter afw;
-    String expectedContent = "hello world";
+    @TempDir
+    private static File tmp;
+    private File af;
+    private AtomicFileWriter afw;
+    private String expectedContent = "hello world";
 
-    @BeforeClass
-    public static void computePermissions() throws IOException {
-        final File tempDir = tmp.newFolder();
+    @BeforeAll
+    static void computePermissions() throws IOException {
+        final File tempDir = newFolder(tmp, "junit");
         final File newFile = new File(tempDir, "blah");
         assertThat(newFile.createNewFile(), is(true));
         if (!isPosixSupported(newFile)) {
@@ -66,23 +65,23 @@ public class AtomicFileWriterTest {
         return posixSupported;
     }
 
-    @Before
-    public void setUp() throws IOException {
-        af = tmp.newFile();
+    @BeforeEach
+    void setUp() throws IOException {
+        af = File.createTempFile("junit", null, tmp);
         Files.writeString(af.toPath(), PREVIOUS, Charset.defaultCharset());
         afw = new AtomicFileWriter(af.toPath(), Charset.defaultCharset());
     }
 
-    @After
-    public void tearDown() throws IOException {
+    @AfterEach
+    void tearDown() throws IOException {
         afw.abort();
     }
 
     @Test
-    public void symlinkToDirectory() throws Exception {
+    void symlinkToDirectory() throws Exception {
         assumeFalse(Functions.isWindows());
-        final File folder = tmp.newFolder();
-        final File containingSymlink = tmp.newFolder();
+        final File folder = newFolder(tmp, "junit");
+        final File containingSymlink = newFolder(tmp, "junit");
         final Path zeSymlink = Files.createSymbolicLink(Paths.get(containingSymlink.getAbsolutePath(), "ze_symlink"),
                                                          folder.toPath());
 
@@ -93,13 +92,13 @@ public class AtomicFileWriterTest {
     }
 
     @Test
-    public void createFile() {
+    void createFile() {
         // Verify the file we created exists
         assertTrue(Files.exists(afw.getTemporaryPath()));
     }
 
     @Test
-    public void writeToAtomicFile() throws Exception {
+    void writeToAtomicFile() throws Exception {
         // Given
         afw.write(expectedContent, 0, expectedContent.length());
         afw.write(expectedContent);
@@ -109,12 +108,11 @@ public class AtomicFileWriterTest {
         afw.flush();
 
         // Then
-        assertEquals("File writer did not properly flush to temporary file",
-                expectedContent.length() * 2 + 1, Files.size(afw.getTemporaryPath()));
+        assertEquals(expectedContent.length() * 2 + 1, Files.size(afw.getTemporaryPath()), "File writer did not properly flush to temporary file");
     }
 
     @Test
-    public void commitToFile() throws Exception {
+    void commitToFile() throws Exception {
         // Given
         afw.write(expectedContent, 0, expectedContent.length());
         afw.write(new char[]{'h', 'e', 'y'}, 0, 3);
@@ -128,7 +126,7 @@ public class AtomicFileWriterTest {
     }
 
     @Test
-    public void abortDeletesTmpFile() throws Exception {
+    void abortDeletesTmpFile() throws Exception {
         // Given
         afw.write(expectedContent, 0, expectedContent.length());
 
@@ -141,15 +139,15 @@ public class AtomicFileWriterTest {
     }
 
     @Test
-    public void indexOutOfBoundsLeavesOriginalUntouched() throws Exception {
+    void indexOutOfBoundsLeavesOriginalUntouched() throws Exception {
         // Given
         assertThrows(IndexOutOfBoundsException.class, () -> afw.write(expectedContent, 0, expectedContent.length() + 10));
         assertEquals(PREVIOUS, Files.readString(af.toPath(), Charset.defaultCharset()));
     }
 
     @Test
-    public void badPath() throws Exception {
-        final File newFile = tmp.newFile();
+    void badPath() throws Exception {
+        final File newFile = File.createTempFile("junit", null, tmp);
         File parentExistsAndIsAFile = new File(newFile, "badChild");
 
         assertTrue(newFile.exists());
@@ -163,12 +161,12 @@ public class AtomicFileWriterTest {
 
     @Issue("JENKINS-48407")
     @Test
-    public void checkPermissionsRespectUmask() throws IOException {
+    void checkPermissionsRespectUmask() throws IOException {
 
-        final File newFile = tmp.newFile();
+        final File newFile = File.createTempFile("junit", null, tmp);
         boolean posixSupported = isPosixSupported(newFile);
 
-        assumeThat(posixSupported, is(true));
+        assumeTrue(posixSupported);
 
         // given
         Path filePath = newFile.toPath();
@@ -184,4 +182,13 @@ public class AtomicFileWriterTest {
 
         assertThat(Files.getPosixFilePermissions(filePath), equalTo(DEFAULT_GIVEN_PERMISSIONS));
     }
+
+    private static File newFolder(File root, String... subDirs) throws IOException {
+        String subFolder = String.join("/", subDirs);
+        File result = new File(root, subFolder);
+        if (!result.exists() && !result.mkdirs()) {
+            throw new IOException("Couldn't create folders " + root);
+        }
+        return result;
+    }
 }

core/src/test/java/hudson/util/CompoundEnumerationTest.java

@@ -1,17 +1,17 @@
 package hudson.util;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.util.Collections;
 import java.util.List;
 import java.util.stream.Collectors;
 import java.util.stream.IntStream;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-public class CompoundEnumerationTest {
+class CompoundEnumerationTest {
 
     @Test
-    public void smokes() {
+    void smokes() {
         assertEquals(
                 rangeClosed(1, 12),
                 Collections.list(
@@ -22,7 +22,7 @@ public class CompoundEnumerationTest {
     }
 
     @Test
-    public void empty() {
+    void empty() {
         assertEquals(Collections.emptyList(), Collections.list(new CompoundEnumeration<>()));
         assertEquals(
                 Collections.emptyList(),
@@ -42,7 +42,7 @@ public class CompoundEnumerationTest {
     }
 
     @Test
-    public void gaps() {
+    void gaps() {
         assertEquals(
                 rangeClosed(1, 8),
                 Collections.list(

core/src/test/java/hudson/util/ConsistentHashTest.java

@@ -24,12 +24,12 @@
 
 package hudson.util;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNull;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.HashMap;
 import java.util.HashSet;
@@ -37,18 +37,18 @@ import java.util.Iterator;
 import java.util.Map;
 import java.util.Random;
 import java.util.Set;
-import org.junit.Ignore;
-import org.junit.Test;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
 
 /**
  * @author Kohsuke Kawaguchi
  */
-public class ConsistentHashTest {
+class ConsistentHashTest {
     /**
      * Just some random tests to ensure that we have no silly NPE or that kind of error.
      */
     @Test
-    public void basic() {
+    void basic() {
         ConsistentHash<String> hash = new ConsistentHash<>();
         hash.add("data1");
         hash.add("data2");
@@ -77,7 +77,7 @@ public class ConsistentHashTest {
      * Uneven distribution should result in uneven mapping.
      */
     @Test
-    public void unevenDistribution() {
+    void unevenDistribution() {
         ConsistentHash<String> hash = new ConsistentHash<>();
         hash.add("Even", 10);
         hash.add("Odd", 100);
@@ -102,7 +102,7 @@ public class ConsistentHashTest {
      * Removal shouldn't affect existing nodes
      */
     @Test
-    public void removal() {
+    void removal() {
         ConsistentHash<Integer> hash = new ConsistentHash<>();
         for (int i = 0; i < 10; i++) {
             hash.add(i);
@@ -127,7 +127,7 @@ public class ConsistentHashTest {
     }
 
     @Test
-    public void emptyBehavior() {
+    void emptyBehavior() {
         ConsistentHash<String> hash = new ConsistentHash<>();
         assertEquals(0, hash.countAllPoints());
         assertFalse(hash.list(0).iterator().hasNext());
@@ -136,7 +136,7 @@ public class ConsistentHashTest {
     }
 
     @Test
-    public void countAllPoints() {
+    void countAllPoints() {
         ConsistentHash<String> hash = new ConsistentHash<>();
         assertEquals(0, hash.countAllPoints());
         hash.add("foo", 10);
@@ -148,7 +148,7 @@ public class ConsistentHashTest {
     }
 
     @Test
-    public void defaultReplicationIsOneHundred() {
+    void defaultReplicationIsOneHundred() {
         ConsistentHash<String> hash = new ConsistentHash<>();
         assertEquals(0, hash.countAllPoints());
         hash.add("foo");
@@ -156,7 +156,7 @@ public class ConsistentHashTest {
     }
 
     @Test
-    public void setCustomDefaultReplication() {
+    void setCustomDefaultReplication() {
         ConsistentHash<String> hash = new ConsistentHash<>((ConsistentHash.Hash<String>) ConsistentHash.DEFAULT_HASH, 7);
         assertEquals(0, hash.countAllPoints());
         hash.add("foo");
@@ -164,7 +164,7 @@ public class ConsistentHashTest {
     }
 
     @Test
-    public void usesCustomHash() {
+    void usesCustomHash() {
         final RuntimeException exception = new RuntimeException();
         ConsistentHash.Hash<String> hashFunction = str -> {
             throw exception;
@@ -179,8 +179,8 @@ public class ConsistentHashTest {
      * This test doesn't fail but it's written to measure the performance of the consistent hash function with large data set.
      */
     @Test
-    @Ignore("Helper test for performance, no assertion")
-    public void speed() {
+    @Disabled("Helper test for performance, no assertion")
+    void speed() {
         Map<String, Integer> data = new CopyOnWriteMap.Hash<>();
         for (int i = 0; i < 1000; i++) {
             data.put("node" + i, 100);

core/src/test/java/hudson/util/CopyOnWriteListTest.java

@@ -25,20 +25,20 @@
 package hudson.util;
 
 import static org.hamcrest.MatcherAssert.assertThat;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 import static org.xmlunit.matchers.CompareMatcher.isSimilarTo;
 
 import java.util.ArrayList;
 import java.util.List;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.xmlunit.diff.DefaultNodeMatcher;
 import org.xmlunit.diff.ElementSelectors;
 
 /**
  * @author Kohsuke Kawaguchi, Alan Harder
  */
-public class CopyOnWriteListTest {
+class CopyOnWriteListTest {
 
     public static final class TestData {
         CopyOnWriteList list1 = new CopyOnWriteList();
@@ -49,7 +49,7 @@ public class CopyOnWriteListTest {
      * Verify that the serialization form of List and CopyOnWriteList are the same.
      */
     @Test
-    public void serialization() {
+    void serialization() {
         XStream2 xs = new XStream2();
         TestData td = new TestData();
 

core/src/test/java/hudson/util/CopyOnWriteMapTest.java

@@ -24,19 +24,19 @@
 
 package hudson.util;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.util.Comparator;
 import java.util.HashMap;
 import java.util.Map;
 import java.util.TreeMap;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * @author Mike Dillon, Alan Harder
  */
-public class CopyOnWriteMapTest {
+class CopyOnWriteMapTest {
     public static final class HashData {
         CopyOnWriteMap.Hash<String, String> map1 = new CopyOnWriteMap.Hash<>();
         HashMap<String, String> map2 = new HashMap<>();
@@ -45,14 +45,16 @@ public class CopyOnWriteMapTest {
     /**
      * Verify that serialization form of CopyOnWriteMap.Hash and HashMap are the same.
      */
-    @Test public void hashSerialization() {
+    @Test
+    void hashSerialization() {
         HashData td = new HashData();
         XStream2 xs = new XStream2();
 
         String out = xs.toXML(td);
-        assertEquals("empty maps", "<hudson.util.CopyOnWriteMapTest_-HashData>"
+        assertEquals("<hudson.util.CopyOnWriteMapTest_-HashData>"
                 + "<map1/><map2/></hudson.util.CopyOnWriteMapTest_-HashData>",
-                out.replaceAll("\\s+", ""));
+                out.replaceAll("\\s+", ""),
+                "empty maps");
         HashData td2 = (HashData) xs.fromXML(out);
         assertTrue(td2.map1.isEmpty());
         assertTrue(td2.map2.isEmpty());
@@ -60,11 +62,12 @@ public class CopyOnWriteMapTest {
         td.map1.put("foo1", "bar1");
         td.map2.put("foo2", "bar2");
         out = xs.toXML(td);
-        assertEquals("maps", "<hudson.util.CopyOnWriteMapTest_-HashData><map1>"
+        assertEquals("<hudson.util.CopyOnWriteMapTest_-HashData><map1>"
                 + "<entry><string>foo1</string><string>bar1</string></entry></map1>"
                 + "<map2><entry><string>foo2</string><string>bar2</string></entry>"
                 + "</map2></hudson.util.CopyOnWriteMapTest_-HashData>",
-                out.replaceAll("\\s+", ""));
+                out.replaceAll("\\s+", ""),
+                "maps");
         td2 = (HashData) xs.fromXML(out);
         assertEquals("bar1", td2.map1.get("foo1"));
         assertEquals("bar2", td2.map2.get("foo2"));
@@ -89,15 +92,17 @@ public class CopyOnWriteMapTest {
      * Verify that an empty CopyOnWriteMap.Tree can be serialized,
      * and that serialization form is the same as a standard TreeMap.
      */
-    @Test public void treeSerialization() {
+    @Test
+    void treeSerialization() {
         TreeData td = new TreeData();
         XStream2 xs = new XStream2();
 
         String out = xs.toXML(td);
-        assertEquals("empty maps", "<hudson.util.CopyOnWriteMapTest_-TreeData>"
+        assertEquals("<hudson.util.CopyOnWriteMapTest_-TreeData>"
                 + "<map1/><map2/>"
                 + "</hudson.util.CopyOnWriteMapTest_-TreeData>",
-                out.replaceAll("\\s+", ""));
+                out.replaceAll("\\s+", ""),
+                "empty maps");
         TreeData td2 = (TreeData) xs.fromXML(out);
         assertTrue(td2.map1.isEmpty());
         assertTrue(td2.map2.isEmpty());
@@ -106,20 +111,22 @@ public class CopyOnWriteMapTest {
         td.map1.put("foo1", "bar1");
         td.map2.put("foo2", "bar2");
         out = xs.toXML(td);
-        assertEquals("maps", "<hudson.util.CopyOnWriteMapTest_-TreeData><map1>"
+        assertEquals("<hudson.util.CopyOnWriteMapTest_-TreeData><map1>"
                 + "<comparator class=\"java.lang.String$CaseInsensitiveComparator\"/>"
                 + "<entry><string>foo1</string><string>bar1</string></entry></map1>"
                 + "<map2><comparator class=\"java.lang.String$CaseInsensitiveComparator\""
                 + " reference=\"../../map1/comparator\"/>"
                 + "<entry><string>foo2</string><string>bar2</string></entry></map2>"
                 + "</hudson.util.CopyOnWriteMapTest_-TreeData>",
-                out.replaceAll(">\\s+<", "><"));
+                out.replaceAll(">\\s+<", "><"),
+                "maps");
         td2 = (TreeData) xs.fromXML(out);
         assertEquals("bar1", td2.map1.get("foo1"));
         assertEquals("bar2", td2.map2.get("foo2"));
     }
 
-    @Test public void equalsHashCodeToString() {
+    @Test
+    void equalsHashCodeToString() {
         Map<String, Integer> m1 = new TreeMap<>();
         Map<String, Integer> m2 = new CopyOnWriteMap.Tree<>();
         m1.put("foo", 5);

core/src/test/java/hudson/util/CyclicGraphDetectorTest.java

@@ -1,19 +1,19 @@
 package hudson.util;
 
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import hudson.util.CyclicGraphDetector.CycleDetectedException;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.LinkedHashSet;
 import java.util.Set;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * @author Kohsuke Kawaguchi
  */
-public class CyclicGraphDetectorTest {
+class CyclicGraphDetectorTest {
 
     private static class Edge {
         String src, dst;
@@ -61,28 +61,27 @@ public class CyclicGraphDetectorTest {
         }
 
         void mustContainCycle(String... members) {
-            final CycleDetectedException e = assertThrows("Cycle expected",
-                    CycleDetectedException.class, this::check);
+            final CycleDetectedException e = assertThrows(CycleDetectedException.class, this::check, "Cycle expected");
 
             final String msg = "Expected cycle of " + Arrays.asList(members) + " but found " + e.cycle;
             for (String s : members) {
-                assertTrue(msg, e.cycle.contains(s));
+                assertTrue(e.cycle.contains(s), msg);
             }
         }
     }
 
     @Test
-    public void cycle1() {
+    void cycle1() {
         new Graph().e("A", "B").e("B", "C").e("C", "A").mustContainCycle("A", "B", "C");
     }
 
     @Test
-    public void cycle2() {
+    void cycle2() {
         new Graph().e("A", "B").e("B", "C").e("C", "C").mustContainCycle("C");
     }
 
     @Test
-    public void cycle3() {
+    void cycle3() {
         new Graph().e("A", "B").e("B", "C").e("C", "D").e("B", "E").e("E", "D").e("E", "A").mustContainCycle("A", "B", "E");
     }
 }

core/src/test/java/hudson/util/DescribableListTest.java

@@ -27,21 +27,21 @@ package hudson.util;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.arrayContaining;
 import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import com.thoughtworks.xstream.converters.basic.AbstractSingleValueConverter;
 import hudson.model.Describable;
 import hudson.model.Descriptor;
 import hudson.model.Saveable;
 import java.util.concurrent.atomic.AtomicInteger;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.jvnet.hudson.test.Issue;
 
-public class DescribableListTest {
+class DescribableListTest {
 
     @Issue("JENKINS-49054")
     @Test
-    public void exceptionDuringUnmarshalling() {
+    void exceptionDuringUnmarshalling() {
         Data data = new Data();
         data.list.add(new Datum(1));
         data.list.add(new Datum(2));
@@ -54,7 +54,7 @@ public class DescribableListTest {
     }
 
     @Test
-    public void replace() throws Exception {
+    void replace() throws Exception {
         AtomicInteger count = new AtomicInteger();
         DescribableList<Datum, Descriptor<Datum>> list = new DescribableList<>((Saveable) count::incrementAndGet);
         list.add(new Datum(1));

core/src/test/java/hudson/util/DirScannerTest.java

@@ -24,24 +24,25 @@
 
 package hudson.util;
 
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import hudson.FilePath;
 import java.io.File;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 
 /**
  * @author Christoph Thelen
  */
-public class DirScannerTest {
+class DirScannerTest {
 
-    @Rule public TemporaryFolder tmpRule = new TemporaryFolder();
+    @TempDir
+    private File tmpRule;
 
-    @Test public void globShouldUseDefaultExcludes() throws Exception {
-        FilePath tmp = new FilePath(tmpRule.getRoot());
+    @Test
+    void globShouldUseDefaultExcludes() throws Exception {
+        FilePath tmp = new FilePath(tmpRule);
         try {
             tmp.child(".gitignore").touch(0);
             FilePath git = tmp.child(".git");
@@ -63,8 +64,9 @@ public class DirScannerTest {
         }
     }
 
-    @Test public void globShouldIgnoreDefaultExcludesByRequest() throws Exception {
-        FilePath tmp = new FilePath(tmpRule.getRoot());
+    @Test
+    void globShouldIgnoreDefaultExcludesByRequest() throws Exception {
+        FilePath tmp = new FilePath(tmpRule);
         try {
             tmp.child(".gitignore").touch(0);
             FilePath git = tmp.child(".git");

core/src/test/java/hudson/util/FileChannelWriterTest.java

@@ -2,7 +2,7 @@ package hudson.util;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.equalTo;
-import static org.junit.Assert.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertThrows;
 
 import java.io.File;
 import java.io.IOException;
@@ -10,26 +10,26 @@ import java.nio.channels.ClosedChannelException;
 import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.StandardOpenOption;
-import org.junit.Before;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 
-public class FileChannelWriterTest {
-    @Rule
-    public TemporaryFolder temporaryFolder = new TemporaryFolder();
+class FileChannelWriterTest {
 
-    File file;
-    FileChannelWriter writer;
+    @TempDir
+    private File temporaryFolder;
 
-    @Before
-    public void setUp() throws Exception {
-        file = temporaryFolder.newFile();
+    private File file;
+    private FileChannelWriter writer;
+
+    @BeforeEach
+    void setUp() throws Exception {
+        file = File.createTempFile("junit", null, temporaryFolder);
         writer = new FileChannelWriter(file.toPath(), StandardCharsets.UTF_8, true, true,  StandardOpenOption.WRITE);
     }
 
     @Test
-    public void write() throws Exception {
+    void write() throws Exception {
         writer.write("helloooo");
         writer.close();
 
@@ -38,7 +38,7 @@ public class FileChannelWriterTest {
 
 
     @Test
-    public void flush() throws Exception {
+    void flush() throws Exception {
         writer.write("hello é è à".toCharArray());
 
         writer.flush();
@@ -46,7 +46,7 @@ public class FileChannelWriterTest {
     }
 
     @Test
-    public void close() throws Exception {
+    void close() throws Exception {
         writer.write("helloooo");
         writer.close();
 

core/src/test/java/hudson/util/FormValidationTest.java

@@ -28,35 +28,35 @@ import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.not;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.IOException;
 import java.net.URI;
 import java.util.Arrays;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * @author sogabe
  */
-public class FormValidationTest {
+class FormValidationTest {
 
     @Test
-    public void testValidateRequired_OK() {
+    void testValidateRequired_OK() {
         FormValidation actual = FormValidation.validateRequired("Name");
         assertEquals(FormValidation.ok(), actual);
     }
 
     @Test
-    public void testValidateRequired_Null() {
+    void testValidateRequired_Null() {
         FormValidation actual = FormValidation.validateRequired(null);
         assertNotNull(actual);
         assertEquals(FormValidation.Kind.ERROR, actual.kind);
     }
 
     @Test
-    public void testValidateRequired_Empty() {
+    void testValidateRequired_Empty() {
         FormValidation actual = FormValidation.validateRequired("  ");
         assertNotNull(actual);
         assertEquals(FormValidation.Kind.ERROR, actual.kind);
@@ -64,17 +64,17 @@ public class FormValidationTest {
 
     // @Issue("JENKINS-7438")
     @Test
-    public void testMessage() {
+    void testMessage() {
         assertEquals("test msg", FormValidation.errorWithMarkup("test msg").getMessage());
     }
 
     @Test
-    public void aggregateZeroValidations() {
+    void aggregateZeroValidations() {
         assertEquals(FormValidation.ok(), aggregate());
     }
 
     @Test
-    public void aggregateSingleValidations() {
+    void aggregateSingleValidations() {
         FormValidation ok = FormValidation.ok();
         FormValidation warning = FormValidation.warning("");
         FormValidation error = FormValidation.error("");
@@ -85,7 +85,7 @@ public class FormValidationTest {
     }
 
     @Test
-    public void aggregateSeveralValidations() {
+    void aggregateSeveralValidations() {
         FormValidation ok = FormValidation.ok("ok_message");
         FormValidation warning = FormValidation.warning("warning_message");
         FormValidation error = FormValidation.error("error_message");
@@ -115,13 +115,13 @@ public class FormValidationTest {
     }
 
     @Test
-    public void formValidationException() {
+    void formValidationException() {
         FormValidation fv = FormValidation.error(new Exception("<html"), "Message<html");
         assertThat(fv.renderHtml(), not(containsString("<html")));
     }
 
     @Test
-    public void testUrlCheck() throws IOException {
+    void testUrlCheck() throws IOException {
         FormValidation.URLCheck urlCheck = new FormValidation.URLCheck() {
             @Override
             protected FormValidation check() throws IOException {

core/src/test/java/hudson/util/GraphTest.java

@@ -24,9 +24,10 @@
 
 package hudson.util;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import java.awt.Dimension;
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 public class GraphTest {
 
@@ -34,25 +35,25 @@ public class GraphTest {
     public static final int DEFAULT_H = 300;
 
     @Test
-    public void testDimensions() {
+    void testDimensions() {
         final Dimension keep = Graph.safeDimension(Graph.MAX_AREA / 1_000, 1000, DEFAULT_W, DEFAULT_H);
-        Assert.assertEquals(Graph.MAX_AREA / 1_000, keep.width);
-        Assert.assertEquals(1_000, keep.height);
+        assertEquals(Graph.MAX_AREA / 1_000, keep.width);
+        assertEquals(1_000, keep.height);
 
         final Dimension keep2 = Graph.safeDimension(Graph.MAX_AREA / 2, 2, DEFAULT_W, DEFAULT_H);
-        Assert.assertEquals(Graph.MAX_AREA / 2, keep2.width);
-        Assert.assertEquals(2, keep2.height);
+        assertEquals(Graph.MAX_AREA / 2, keep2.width);
+        assertEquals(2, keep2.height);
 
         final Dimension resetArea = Graph.safeDimension(Graph.MAX_AREA, Graph.MAX_AREA, DEFAULT_W, DEFAULT_H);
-        Assert.assertEquals(DEFAULT_W, resetArea.width);
-        Assert.assertEquals(DEFAULT_H, resetArea.height);
+        assertEquals(DEFAULT_W, resetArea.width);
+        assertEquals(DEFAULT_H, resetArea.height);
 
         final Dimension resetNegativeWidth = Graph.safeDimension(-50, 1000, DEFAULT_W, DEFAULT_H);
-        Assert.assertEquals(DEFAULT_W, resetNegativeWidth.width);
-        Assert.assertEquals(DEFAULT_H, resetNegativeWidth.height);
+        assertEquals(DEFAULT_W, resetNegativeWidth.width);
+        assertEquals(DEFAULT_H, resetNegativeWidth.height);
 
         final Dimension resetNegativeHeight = Graph.safeDimension(1000, -50, DEFAULT_W, DEFAULT_H);
-        Assert.assertEquals(DEFAULT_W, resetNegativeHeight.width);
-        Assert.assertEquals(DEFAULT_H, resetNegativeHeight.height);
+        assertEquals(DEFAULT_W, resetNegativeHeight.width);
+        assertEquals(DEFAULT_H, resetNegativeHeight.height);
     }
 }

core/src/test/java/hudson/util/IsOverriddenTest.java

@@ -26,30 +26,26 @@ package hudson.util;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertAll;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import hudson.Util;
 import java.io.PrintWriter;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.ErrorCollector;
+import org.junit.jupiter.api.Test;
 import org.jvnet.hudson.test.Issue;
 
 /**
  * Test for {@link Util#isOverridden} method.
  */
-public class IsOverriddenTest {
-
-    @Rule
-    public ErrorCollector errors = new ErrorCollector();
+class IsOverriddenTest {
 
     /**
      * Test that a method is found by isOverridden even when it is inherited from an intermediate class.
      */
     @Test
-    public void isOverriddenTest() {
+    void isOverriddenTest() {
         assertTrue(Util.isOverridden(Base.class, Derived.class, "method"));
         assertTrue(Util.isOverridden(Base.class, Intermediate.class, "method"));
         assertFalse(Util.isOverridden(Base.class, Base.class, "method"));
@@ -64,13 +60,13 @@ public class IsOverriddenTest {
      * Trying to check for a method which does not exist in the hierarchy.
      */
     @Test
-    public void isOverriddenNegativeTest() {
+    void isOverriddenNegativeTest() {
         assertThrows(IllegalArgumentException.class, () -> Util.isOverridden(Base.class, Derived.class, "method2"));
     }
 
     /** Specifying a base class that is not a base class should result in an error. */
     @Test
-    public void badHierarchyIsReported() {
+    void badHierarchyIsReported() {
         assertThrows(IllegalArgumentException.class, () -> Util.isOverridden(Derived.class, Base.class, "method"));
     }
 
@@ -78,7 +74,7 @@ public class IsOverriddenTest {
      * Do not inspect private methods.
      */
     @Test
-    public void avoidPrivateMethodsInspection() {
+    void avoidPrivateMethodsInspection() {
         assertThrows(IllegalArgumentException.class, () -> Util.isOverridden(Base.class, Intermediate.class, "aPrivateMethod"));
     }
 
@@ -106,39 +102,17 @@ public class IsOverriddenTest {
 
     @Issue("JENKINS-62723")
     @Test
-    public void finalOverrides() {
-        errors.checkSucceeds(() -> {
-            assertThat("X1 overrides X.m1", Util.isOverridden(X.class, X1.class, "m1"), is(true));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("x1 does not override x.m2", Util.isOverridden(X.class, X1.class, "m2"), is(false));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("X2 overrides X.m1", Util.isOverridden(X.class, X2.class, "m1"), is(true));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("X2 does not override X.m2", Util.isOverridden(X.class, X2.class, "m2"), is(false));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("X3 overrides X.m1", Util.isOverridden(X.class, X3.class, "m1"), is(true));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("X3 overrides X.m2", Util.isOverridden(X.class, X3.class, "m2"), is(true));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("X4 overrides X.m1", Util.isOverridden(X.class, X4.class, "m1"), is(true));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("X4 overrides X.m2", Util.isOverridden(X.class, X4.class, "m2"), is(true));
-            return null;
-        });
+    void finalOverrides() {
+        assertAll(
+                () -> assertThat("X1 overrides X.m1", Util.isOverridden(X.class, X1.class, "m1"), is(true)),
+                () -> assertThat("x1 does not override x.m2", Util.isOverridden(X.class, X1.class, "m2"), is(false)),
+                () -> assertThat("X2 overrides X.m1", Util.isOverridden(X.class, X2.class, "m1"), is(true)),
+                () -> assertThat("X2 does not override X.m2", Util.isOverridden(X.class, X2.class, "m2"), is(false)),
+                () -> assertThat("X3 overrides X.m1", Util.isOverridden(X.class, X3.class, "m1"), is(true)),
+                () -> assertThat("X3 overrides X.m2", Util.isOverridden(X.class, X3.class, "m2"), is(true)),
+                () -> assertThat("X4 overrides X.m1", Util.isOverridden(X.class, X4.class, "m1"), is(true)),
+                () -> assertThat("X4 overrides X.m2", Util.isOverridden(X.class, X4.class, "m2"), is(true))
+        );
     }
 
     public interface X {
@@ -171,57 +145,23 @@ public class IsOverriddenTest {
 
     @Issue("JENKINS-62723")
     @Test
-    public void baseInterface() {
+    void baseInterface() {
         // Normal case: classes implementing interface methods
-        errors.checkSucceeds(() -> {
-            assertThat("I1 does not override I1.foo", Util.isOverridden(I1.class, I1.class, "foo"), is(false));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("I2 does not override I1.foo", Util.isOverridden(I1.class, I2.class, "foo"), is(false));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("C1 does not override I1.foo", Util.isOverridden(I1.class, C1.class, "foo"), is(false));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("C2 does not override I1.foo", Util.isOverridden(I1.class, C2.class, "foo"), is(false));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("C3 overrides I1.foo", Util.isOverridden(I1.class, C3.class, "foo"), is(true));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("C4 overrides I1.foo", Util.isOverridden(I1.class, C4.class, "foo"), is(true));
-            return null;
-        });
-        // Special case: interfaces providing default implementation of base interface
-        errors.checkSucceeds(() -> {
-            assertThat("I1 does not override I1.bar", Util.isOverridden(I1.class, I1.class, "bar"), is(false));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("I2 overrides I1.bar", Util.isOverridden(I1.class, I2.class, "bar"), is(true));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("C1 does not override I1.bar", Util.isOverridden(I1.class, C1.class, "bar"), is(false));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("C2 overrides I1.bar (via I2)", Util.isOverridden(I1.class, C2.class, "bar"), is(true));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("C3 overrides I1.bar (via I2)", Util.isOverridden(I1.class, C3.class, "bar"), is(true));
-            return null;
-        });
-        errors.checkSucceeds(() -> {
-            assertThat("C4 overrides I1.bar", Util.isOverridden(I1.class, C4.class, "bar"), is(true));
-            return null;
-        });
+        assertAll(
+                () -> assertThat("I1 does not override I1.foo", Util.isOverridden(I1.class, I1.class, "foo"), is(false)),
+                () -> assertThat("I2 does not override I1.foo", Util.isOverridden(I1.class, I2.class, "foo"), is(false)),
+                () -> assertThat("C1 does not override I1.foo", Util.isOverridden(I1.class, C1.class, "foo"), is(false)),
+                () -> assertThat("C2 does not override I1.foo", Util.isOverridden(I1.class, C2.class, "foo"), is(false)),
+                () -> assertThat("C3 overrides I1.foo", Util.isOverridden(I1.class, C3.class, "foo"), is(true)),
+                () -> assertThat("C4 overrides I1.foo", Util.isOverridden(I1.class, C4.class, "foo"), is(true)),
+                // Special case: interfaces providing default implementation of base interface
+                () -> assertThat("I1 does not override I1.bar", Util.isOverridden(I1.class, I1.class, "bar"), is(false)),
+                () -> assertThat("I2 overrides I1.bar", Util.isOverridden(I1.class, I2.class, "bar"), is(true)),
+                () -> assertThat("C1 does not override I1.bar", Util.isOverridden(I1.class, C1.class, "bar"), is(false)),
+                () -> assertThat("C2 overrides I1.bar (via I2)", Util.isOverridden(I1.class, C2.class, "bar"), is(true)),
+                () -> assertThat("C3 overrides I1.bar (via I2)", Util.isOverridden(I1.class, C3.class, "bar"), is(true)),
+                () -> assertThat("C4 overrides I1.bar", Util.isOverridden(I1.class, C4.class, "bar"), is(true))
+        );
     }
 
     private interface I1 {

core/src/test/java/hudson/util/IteratorsTest.java

@@ -28,23 +28,23 @@ import static java.util.Arrays.asList;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.not;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import hudson.util.Iterators.CountingPredicate;
 import java.util.Iterator;
 import java.util.List;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.jvnet.hudson.test.Issue;
 
 /**
  * @author Kohsuke Kawaguchi
  */
-public class IteratorsTest {
+class IteratorsTest {
 
     @Test
-    public void reverseSequence() {
+    void reverseSequence() {
         List<Integer> lst = Iterators.reverseSequence(1, 4);
         assertEquals(3, (int) lst.get(0));
         assertEquals(2, (int) lst.get(1));
@@ -53,7 +53,7 @@ public class IteratorsTest {
     }
 
     @Test
-    public void sequence() {
+    void sequence() {
         List<Integer> lst = Iterators.sequence(1, 4);
         assertEquals(1, (int) lst.get(0));
         assertEquals(2, (int) lst.get(1));
@@ -62,7 +62,7 @@ public class IteratorsTest {
     }
 
     @Test
-    public void wrap() {
+    void wrap() {
         List<Integer> lst = Iterators.sequence(1, 4);
         Iterable<Integer> wrapped = Iterators.wrap(lst);
         assertThat(wrapped, not(instanceOf(List.class)));
@@ -77,7 +77,7 @@ public class IteratorsTest {
     }
 
     @Test
-    public void limit() {
+    void limit() {
         assertEquals("[0]", com.google.common.collect.Iterators.toString(Iterators.limit(asList(0, 1, 2, 3, 4).iterator(), EVEN)));
         assertEquals("[]", com.google.common.collect.Iterators.toString(Iterators.limit(asList(1, 2, 4, 6).iterator(), EVEN)));
     }
@@ -86,7 +86,7 @@ public class IteratorsTest {
 
     @Issue("JENKINS-51779")
     @Test
-    public void skip() {
+    void skip() {
         List<Integer> lst = Iterators.sequence(1, 4);
         Iterator<Integer> it = lst.iterator();
         Iterators.skip(it, 0);

core/src/test/java/hudson/util/JSONObjectResponseTest.java

@@ -24,19 +24,20 @@
 
 package hudson.util;
 
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
 import java.util.HashMap;
 import java.util.Map;
 import net.sf.json.JSONObject;
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * @author <a href="mailto:tom.fennelly@gmail.com">tom.fennelly@gmail.com</a>
  */
-public class JSONObjectResponseTest {
+class JSONObjectResponseTest {
 
     @Test
-    public void test() {
+    void test() {
         Map<String, String> data = new HashMap<>();
 
         data.put("val_1", "1");
@@ -44,13 +45,13 @@ public class JSONObjectResponseTest {
         HttpResponses.JSONObjectResponse response = new HttpResponses.JSONObjectResponse(data);
         JSONObject payload = response.getJsonObject();
 
-        Assert.assertEquals("ok", payload.getString("status"));
+        assertEquals("ok", payload.getString("status"));
         JSONObject payloadData = payload.getJSONObject("data");
-        Assert.assertEquals("1", payloadData.getString("val_1"));
+        assertEquals("1", payloadData.getString("val_1"));
 
         // change it to an error
         response.error("a message");
-        Assert.assertEquals("error", payload.getString("status"));
-        Assert.assertEquals("a message", payload.getString("message"));
+        assertEquals("error", payload.getString("status"));
+        assertEquals("a message", payload.getString("message"));
     }
 }

core/src/test/java/hudson/util/MultipartFormDataParserTest.java

@@ -24,21 +24,23 @@
 
 package hudson.util;
 
-import org.junit.Assert;
-import org.junit.Test;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import org.junit.jupiter.api.Test;
 
 /**
  * @author <a href="mailto:tom.fennelly@gmail.com">tom.fennelly@gmail.com</a>
  */
-public class MultipartFormDataParserTest {
+class MultipartFormDataParserTest {
 
     @Test
-    public void testIsMultipart() {
-        Assert.assertFalse("Wrongly identified \"multipart/form-data\"", MultipartFormDataParser.isMultiPartForm(null));
-        Assert.assertFalse("Wrongly identified \"multipart/form-data\"", MultipartFormDataParser.isMultiPartForm("blah"));
+    void testIsMultipart() {
+        assertFalse(MultipartFormDataParser.isMultiPartForm(null), "Wrongly identified \"multipart/form-data\"");
+        assertFalse(MultipartFormDataParser.isMultiPartForm("blah"), "Wrongly identified \"multipart/form-data\"");
 
-        Assert.assertTrue("Failed to identify \"multipart/form-data\"", MultipartFormDataParser.isMultiPartForm("multipart/form-data"));
-        Assert.assertTrue("Failed to identify \"multipart/form-data\"", MultipartFormDataParser.isMultiPartForm("multipart/form-data;"));
-        Assert.assertTrue("Failed to identify \"multipart/form-data\"", MultipartFormDataParser.isMultiPartForm("multipart/form-data; boundary=----WebKitFormBoundary8OOwv1Xp4c5XkBmD"));
+        assertTrue(MultipartFormDataParser.isMultiPartForm("multipart/form-data"), "Failed to identify \"multipart/form-data\"");
+        assertTrue(MultipartFormDataParser.isMultiPartForm("multipart/form-data;"), "Failed to identify \"multipart/form-data\"");
+        assertTrue(MultipartFormDataParser.isMultiPartForm("multipart/form-data; boundary=----WebKitFormBoundary8OOwv1Xp4c5XkBmD"), "Failed to identify \"multipart/form-data\"");
     }
 }

core/src/test/java/hudson/util/PackedMapTest.java

@@ -1,15 +1,15 @@
 package hudson.util;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.util.Map;
 import java.util.TreeMap;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * @author Kohsuke Kawaguchi
  */
-public class PackedMapTest {
+class PackedMapTest {
 
     static class Holder {
         PackedMap pm;
@@ -18,7 +18,7 @@ public class PackedMapTest {
     private XStream2 xs = new XStream2();
 
     @Test
-    public void basic() {
+    void basic() {
         Map<String, String> o = new TreeMap<>();
         o.put("a", "b");
         o.put("c", "d");
@@ -35,18 +35,19 @@ public class PackedMapTest {
         h.pm = p;
         String xml = xs.toXML(h);
         assertEquals(
-                "<hudson.util.PackedMapTest_-Holder>\n" +
-                "  <pm>\n" +
-                "    <entry>\n" +
-                "      <string>a</string>\n" +
-                "      <string>b</string>\n" +
-                "    </entry>\n" +
-                "    <entry>\n" +
-                "      <string>c</string>\n" +
-                "      <string>d</string>\n" +
-                "    </entry>\n" +
-                "  </pm>\n" +
-                "</hudson.util.PackedMapTest_-Holder>",
+                """
+                        <hudson.util.PackedMapTest_-Holder>
+                          <pm>
+                            <entry>
+                              <string>a</string>
+                              <string>b</string>
+                            </entry>
+                            <entry>
+                              <string>c</string>
+                              <string>d</string>
+                            </entry>
+                          </pm>
+                        </hudson.util.PackedMapTest_-Holder>""",
                 xml);
 
         xs.fromXML(xml);

core/src/test/java/hudson/util/ProcessTreeTest.java

@@ -1,38 +1,82 @@
 package hudson.util;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertSame;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertSame;
 
-import hudson.ChannelRule;
+import hudson.remoting.Channel;
+import hudson.remoting.ChannelBuilder;
+import hudson.remoting.FastPipedInputStream;
+import hudson.remoting.FastPipedOutputStream;
 import hudson.remoting.VirtualChannel;
 import hudson.util.ProcessTree.OSProcess;
 import hudson.util.ProcessTree.ProcessCallable;
 import java.io.IOException;
+import java.io.Serial;
 import java.io.Serializable;
+import java.io.UncheckedIOException;
+import java.util.concurrent.ExecutorService;
+import java.util.concurrent.Executors;
+import java.util.concurrent.Future;
 import jenkins.security.MasterToSlaveCallable;
-import org.junit.Assume;
-import org.junit.Rule;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.Assumptions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
 /**
  * @author Kohsuke Kawaguchi
  */
-public class ProcessTreeTest {
+class ProcessTreeTest {
 
-    @Rule public ChannelRule channels = new ChannelRule();
+    /**
+     * Two channels that are connected to each other, but shares the same classloader.
+     */
+    private Channel french;
+    private Channel british;
+    private ExecutorService executors;
+
+    @BeforeEach
+    void setUp() throws Exception {
+        executors = Executors.newCachedThreadPool();
+        final FastPipedInputStream p1i = new FastPipedInputStream();
+        final FastPipedInputStream p2i = new FastPipedInputStream();
+        final FastPipedOutputStream p1o = new FastPipedOutputStream(p1i);
+        final FastPipedOutputStream p2o = new FastPipedOutputStream(p2i);
+
+        Future<Channel> f1 = executors.submit(() -> new ChannelBuilder("This side of the channel", executors).withMode(Channel.Mode.BINARY).build(p1i, p2o));
+        Future<Channel> f2 = executors.submit(() -> new ChannelBuilder("The other side of the channel", executors).withMode(Channel.Mode.BINARY).build(p2i, p1o));
+        french = f1.get();
+        british = f2.get();
+    }
+
+    @AfterEach
+    void tearDown() {
+        try {
+            french.close(); // this will automatically initiate the close on the other channel, too.
+            french.join();
+            british.join();
+        } catch (IOException e) {
+            throw new UncheckedIOException(e);
+        } catch (InterruptedException x) {
+            throw new AssertionError(x);
+        }
+        executors.shutdownNow();
+    }
 
     static class  Tag implements Serializable {
         ProcessTree tree;
         OSProcess p;
         int id;
+        @Serial
         private static final long serialVersionUID = 1L;
     }
 
-    @Test public void remoting() throws Exception {
-        Assume.assumeFalse("on some platforms where we fail to list any processes", ProcessTree.get() == ProcessTree.DEFAULT);
+    @Test
+    void remoting() throws Exception {
+        Assumptions.assumeFalse(ProcessTree.get() == ProcessTree.DEFAULT, "on some platforms where we fail to list any processes");
 
-        Tag t = channels.french.call(new MyCallable());
+        Tag t = french.call(new MyCallable());
 
         // make sure the serialization preserved the reference graph
         assertSame(t.p.getTree(), t.tree);
@@ -56,6 +100,7 @@ public class ProcessTreeTest {
             return t;
         }
 
+        @Serial
         private static final long serialVersionUID = 1L;
     }
 

core/src/test/java/hudson/util/RetrierTest.java

@@ -1,7 +1,9 @@
 package hudson.util;
 
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.io.IOException;
 import java.time.Duration;
@@ -9,14 +11,13 @@ import java.time.Instant;
 import java.util.concurrent.Callable;
 import java.util.logging.Level;
 import java.util.logging.Logger;
-import org.junit.Assert;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-public class RetrierTest {
+class RetrierTest {
     private static final Logger LOG = Logger.getLogger(RetrierTest.class.getName());
 
     @Test
-    public void performedAtThirdAttemptTest() throws Exception {
+    void performedAtThirdAttemptTest() throws Exception {
         final int SUCCESSFUL_ATTEMPT = 3;
         final String ACTION = "print";
 
@@ -45,14 +46,14 @@ public class RetrierTest {
 
         // Begin the process
         Boolean finalResult = r.start();
-        Assert.assertTrue(finalResult != null && finalResult);
+        assertTrue(finalResult != null && finalResult);
 
         String text = Messages.Retrier_Success(ACTION, SUCCESSFUL_ATTEMPT);
-        assertTrue(String.format("The log should contain '%s'", text), handler.getView().stream().anyMatch(m -> m.getMessage().contains(text)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().contains(text)), String.format("The log should contain '%s'", text));
     }
 
     @Test
-    public void sleepWorksTest() throws Exception {
+    void sleepWorksTest() throws Exception {
         final int SUCCESSFUL_ATTEMPT = 2;
         final String ACTION = "print";
         final int SLEEP = 500;
@@ -94,21 +95,21 @@ public class RetrierTest {
         long timeElapsed = Duration.between(start, finish).toMillis();
 
         // Check delay works
-        Assert.assertTrue(timeElapsed >= SLEEP);
+        assertTrue(timeElapsed >= SLEEP);
 
         // Check result is true
-        Assert.assertTrue(finalResult != null && finalResult);
+        assertTrue(finalResult != null && finalResult);
 
         // Check the log tell us the sleep time
         String text = Messages.Retrier_Sleeping(SLEEP, ACTION);
-        assertTrue(String.format("The log should contain '%s'", text), handler.getView().stream().anyMatch(m -> m.getMessage().contains(text)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().contains(text)), String.format("The log should contain '%s'", text));
 
         // recover log level
         retrierLogger.setLevel(currentLogLevel);
     }
 
     @Test
-    public void failedActionAfterThreeAttemptsTest() throws Exception {
+    void failedActionAfterThreeAttemptsTest() throws Exception {
         final int ATTEMPTS = 3;
         final String ACTION = "print";
 
@@ -138,15 +139,15 @@ public class RetrierTest {
         // Begin the process
         Boolean finalResult = r.start();
 
-        Assert.assertFalse(finalResult != null && finalResult);
+        assertFalse(finalResult != null && finalResult);
 
         String text = Messages.Retrier_NoSuccess(ACTION, ATTEMPTS);
-        assertTrue(String.format("The log should contain '%s'", text), handler.getView().stream().anyMatch(m -> m.getMessage().contains(text)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().contains(text)), String.format("The log should contain '%s'", text));
 
     }
 
     @Test
-    public void failedActionWithExceptionAfterThreeAttemptsWithoutListenerTest() throws Exception {
+    void failedActionWithExceptionAfterThreeAttemptsWithoutListenerTest() throws Exception {
         final int ATTEMPTS = 3;
         final String ACTION = "print";
 
@@ -174,18 +175,18 @@ public class RetrierTest {
 
         // Begin the process without catching the allowed exceptions
         Boolean finalResult = r.start();
-        Assert.assertNull(finalResult);
+        assertNull(finalResult);
 
         String textNoSuccess = Messages.Retrier_NoSuccess(ACTION, ATTEMPTS);
-        assertTrue(String.format("The log should contain '%s'", textNoSuccess), handler.getView().stream().anyMatch(m -> m.getMessage().contains(textNoSuccess)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().contains(textNoSuccess)), String.format("The log should contain '%s'", textNoSuccess));
 
         String testException = Messages.Retrier_ExceptionFailed(ATTEMPTS, ACTION);
-        assertTrue(String.format("The log should contain '%s'", testException), handler.getView().stream().anyMatch(m -> m.getMessage().startsWith(testException)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().startsWith(testException)), String.format("The log should contain '%s'", testException));
 
     }
 
     @Test
-    public void failedActionWithAllowedExceptionWithListenerChangingResultTest() throws Exception {
+    void failedActionWithAllowedExceptionWithListenerChangingResultTest() throws Exception {
         final int ATTEMPTS = 1;
         final String ACTION = "print";
 
@@ -215,19 +216,19 @@ public class RetrierTest {
 
         // Begin the process catching the allowed exception
         Boolean finalResult = r.start();
-        Assert.assertTrue(finalResult != null && finalResult);
+        assertTrue(finalResult != null && finalResult);
 
         // The action was a success
         String textSuccess = Messages.Retrier_Success(ACTION, ATTEMPTS);
-        assertTrue(String.format("The log should contain '%s'", textSuccess), handler.getView().stream().anyMatch(m -> m.getMessage().contains(textSuccess)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().contains(textSuccess)), String.format("The log should contain '%s'", textSuccess));
 
         // And the message talking about the allowed raised is also there
         String testException = Messages.Retrier_ExceptionFailed(ATTEMPTS, ACTION);
-        assertTrue(String.format("The log should contain '%s'", testException), handler.getView().stream().anyMatch(m -> m.getMessage().startsWith(testException)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().startsWith(testException)), String.format("The log should contain '%s'", testException));
     }
 
     @Test
-    public void failedActionWithAllowedExceptionByInheritanceTest() throws Exception {
+    void failedActionWithAllowedExceptionByInheritanceTest() throws Exception {
         final int ATTEMPTS = 1;
         final String ACTION = "print";
 
@@ -258,19 +259,19 @@ public class RetrierTest {
 
         // Begin the process catching the allowed exception
         Boolean finalResult = r.start();
-        Assert.assertTrue(finalResult != null && finalResult);
+        assertTrue(finalResult != null && finalResult);
 
         // The action was a success
         String textSuccess = Messages.Retrier_Success(ACTION, ATTEMPTS);
-        assertTrue(String.format("The log should contain '%s'", textSuccess), handler.getView().stream().anyMatch(m -> m.getMessage().contains(textSuccess)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().contains(textSuccess)), String.format("The log should contain '%s'", textSuccess));
 
         // And the message talking about the allowed raised is also there
         String testException = Messages.Retrier_ExceptionFailed(ATTEMPTS, ACTION);
-        assertTrue(String.format("The log should contain '%s'", testException), handler.getView().stream().anyMatch(m -> m.getMessage().startsWith(testException)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().startsWith(testException)), String.format("The log should contain '%s'", testException));
     }
 
     @Test
-    public void failedActionWithUnAllowedExceptionTest() {
+    void failedActionWithUnAllowedExceptionTest() {
         final int ATTEMPTS = 1;
         final String ACTION = "print";
 
@@ -298,8 +299,8 @@ public class RetrierTest {
                 .build();
 
         // Begin the process that raises an unexpected exception
-        assertThrows("The process should be exited with an unexpected exception", IOException.class, r::start);
+        assertThrows(IOException.class, r::start, "The process should be exited with an unexpected exception");
         String testFailure = Messages.Retrier_ExceptionThrown(ATTEMPTS, ACTION);
-        assertTrue(String.format("The log should contain '%s'", testFailure), handler.getView().stream().anyMatch(m -> m.getMessage().contains(testFailure)));
+        assertTrue(handler.getView().stream().anyMatch(m -> m.getMessage().contains(testFailure)), String.format("The log should contain '%s'", testFailure));
     }
 }

core/src/test/java/hudson/util/RobustCollectionConverterTest.java

@@ -26,10 +26,10 @@ package hudson.util;
 
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.instanceOf;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import com.thoughtworks.xstream.security.InputManipulationException;
 import hudson.model.Saveable;
@@ -43,27 +43,29 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 import jenkins.util.xstream.CriticalXStreamException;
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
 import org.jvnet.hudson.test.Issue;
 
-public class RobustCollectionConverterTest {
+class RobustCollectionConverterTest {
     private final boolean originalRecordFailures = RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS;
 
-    @Before
-    public void before() {
+    @BeforeEach
+    void before() {
         RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS = true;
     }
 
-    @After
-    public void after() {
+    @AfterEach
+    void after() {
         RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS = originalRecordFailures;
     }
 
     @Test
-    public void workingByDefaultWithSimplePayload() {
+    void workingByDefaultWithSimplePayload() {
         XStream2 xstream2 = new XStream2();
 
         Map<String, String> map = new HashMap<>();
@@ -91,9 +93,10 @@ public class RobustCollectionConverterTest {
      * We had to patch it in order to not be impacted by CVE-2021-43859
      */
     // force timeout to prevent DoS due to test in the case the DoS prevention is broken
-    @Test(timeout = 30 * 1000)
+    @Test
+    @Timeout(value = 30 * 1000, unit = TimeUnit.MILLISECONDS)
     @Issue("SECURITY-2602")
-    public void dosIsPrevented_customProgrammaticallyTimeout() {
+    void dosIsPrevented_customProgrammaticallyTimeout() {
         XStream2 xstream2 = new XStream2();
 
         Set<Object> set = preparePayload();
@@ -105,12 +108,13 @@ public class RobustCollectionConverterTest {
         assertNotNull(cause);
         assertThat(cause, instanceOf(InputManipulationException.class));
         InputManipulationException ime = (InputManipulationException) cause;
-        assertTrue("Limit expected in message", ime.getMessage().contains("exceeds 3 seconds"));
+        assertTrue(ime.getMessage().contains("exceeds 3 seconds"), "Limit expected in message");
     }
 
-    @Test(timeout = 30 * 1000)
+    @Test
+    @Timeout(value = 30 * 1000, unit = TimeUnit.MILLISECONDS)
     @Issue("SECURITY-2602")
-    public void dosIsPrevented_customPropertyTimeout() {
+    void dosIsPrevented_customPropertyTimeout() {
         String currentValue = System.getProperty(XStream2.COLLECTION_UPDATE_LIMIT_PROPERTY_NAME);
         try {
             System.setProperty(XStream2.COLLECTION_UPDATE_LIMIT_PROPERTY_NAME, "4");
@@ -125,7 +129,7 @@ public class RobustCollectionConverterTest {
             assertNotNull(cause);
             assertThat(cause, instanceOf(InputManipulationException.class));
             InputManipulationException ime = (InputManipulationException) cause;
-            assertTrue("Limit expected in message", ime.getMessage().contains("exceeds 4 seconds"));
+            assertTrue(ime.getMessage().contains("exceeds 4 seconds"), "Limit expected in message");
         } finally {
             if (currentValue == null) {
                 System.clearProperty(XStream2.COLLECTION_UPDATE_LIMIT_PROPERTY_NAME);
@@ -136,9 +140,10 @@ public class RobustCollectionConverterTest {
     }
 
     // force timeout to prevent DoS due to test in the case the DoS prevention is broken
-    @Test(timeout = 30 * 1000)
+    @Test
+    @Timeout(value = 30 * 1000, unit = TimeUnit.MILLISECONDS)
     @Issue("SECURITY-2602")
-    public void dosIsPrevented_defaultTimeout() {
+    void dosIsPrevented_defaultTimeout() {
         XStream2 xstream2 = new XStream2();
 
         Set<Object> set = preparePayload();
@@ -149,7 +154,7 @@ public class RobustCollectionConverterTest {
         assertNotNull(cause);
         assertThat(cause, instanceOf(InputManipulationException.class));
         InputManipulationException ime = (InputManipulationException) cause;
-        assertTrue("Limit expected in message", ime.getMessage().contains("exceeds 5 seconds"));
+        assertTrue(ime.getMessage().contains("exceeds 5 seconds"), "Limit expected in message");
     }
 
     // Inspired by https://github.com/x-stream/xstream/commit/e8e88621ba1c85ac3b8620337dd672e0c0c3a846#diff-9fde4ecf1bb4dc9850c031cb161960d2e61e069b386fa0b3db0d57e0e9f5baa
@@ -192,7 +197,7 @@ public class RobustCollectionConverterTest {
 
     @Issue("JENKINS-63343")
     @Test
-    public void checkElementTypes() {
+    void checkElementTypes() {
         var xmlContent =
                 """
                 <hudson.util.RobustCollectionConverterTest_-Data>
@@ -210,7 +215,7 @@ public class RobustCollectionConverterTest {
     }
 
     @Test
-    public void rawtypes() {
+    void rawtypes() {
         var xmlContent =
                 """
                 <hudson.util.RobustCollectionConverterTest_-DataRaw>

core/src/test/java/hudson/util/RobustMapConverterTest.java

@@ -27,31 +27,33 @@ package hudson.util;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.instanceOf;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import com.thoughtworks.xstream.security.InputManipulationException;
 import hudson.model.Saveable;
 import java.io.IOException;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.concurrent.TimeUnit;
 import jenkins.util.xstream.CriticalXStreamException;
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
 import org.jvnet.hudson.test.Issue;
 
-public class RobustMapConverterTest {
+class RobustMapConverterTest {
     private final boolean originalRecordFailures = RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS;
 
-    @Before
-    public void before() {
+    @BeforeEach
+    void before() {
         RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS = true;
     }
 
-    @After
-    public void after() {
+    @AfterEach
+    void after() {
         RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS = originalRecordFailures;
     }
 
@@ -60,9 +62,10 @@ public class RobustMapConverterTest {
      * We had to patch it in order to not be impacted by CVE-2021-43859
      */
     // force timeout to prevent DoS due to test in the case the DoS prevention is broken
-    @Test(timeout = 30 * 1000)
+    @Test
+    @Timeout(value = 30 * 1000, unit = TimeUnit.MILLISECONDS)
     @Issue("SECURITY-2602")
-    public void dosIsPrevented_customProgrammaticallyTimeout() {
+    void dosIsPrevented_customProgrammaticallyTimeout() {
         XStream2 xstream2 = new XStream2();
 
         Map<Object, Object> map = preparePayload();
@@ -75,12 +78,13 @@ public class RobustMapConverterTest {
         assertNotNull(cause);
         assertThat(cause, instanceOf(InputManipulationException.class));
         InputManipulationException ime = (InputManipulationException) cause;
-        assertTrue("Limit expected in message", ime.getMessage().contains("exceeds 3 seconds"));
+        assertTrue(ime.getMessage().contains("exceeds 3 seconds"), "Limit expected in message");
     }
 
-    @Test(timeout = 30 * 1000)
+    @Test
+    @Timeout(value = 30 * 1000, unit = TimeUnit.MILLISECONDS)
     @Issue("SECURITY-2602")
-    public void dosIsPrevented_customPropertyTimeout() {
+    void dosIsPrevented_customPropertyTimeout() {
         String currentValue = System.getProperty(XStream2.COLLECTION_UPDATE_LIMIT_PROPERTY_NAME);
         try {
             System.setProperty(XStream2.COLLECTION_UPDATE_LIMIT_PROPERTY_NAME, "4");
@@ -95,7 +99,7 @@ public class RobustMapConverterTest {
             assertNotNull(cause);
             assertThat(cause, instanceOf(InputManipulationException.class));
             InputManipulationException ime = (InputManipulationException) cause;
-            assertTrue("Limit expected in message", ime.getMessage().contains("exceeds 4 seconds"));
+            assertTrue(ime.getMessage().contains("exceeds 4 seconds"), "Limit expected in message");
         } finally {
             if (currentValue == null) {
                 System.clearProperty(XStream2.COLLECTION_UPDATE_LIMIT_PROPERTY_NAME);
@@ -106,9 +110,10 @@ public class RobustMapConverterTest {
     }
 
     // force timeout to prevent DoS due to test in the case the DoS prevention is broken
-    @Test(timeout = 30 * 1000)
+    @Test
+    @Timeout(value = 30 * 1000, unit = TimeUnit.MILLISECONDS)
     @Issue("SECURITY-2602")
-    public void dosIsPrevented_defaultTimeout() {
+    void dosIsPrevented_defaultTimeout() {
         XStream2 xstream2 = new XStream2();
 
         Map<Object, Object> map = preparePayload();
@@ -119,7 +124,7 @@ public class RobustMapConverterTest {
         assertNotNull(cause);
         assertThat(cause, instanceOf(InputManipulationException.class));
         InputManipulationException ime = (InputManipulationException) cause;
-        assertTrue("Limit expected in message", ime.getMessage().contains("exceeds 5 seconds"));
+        assertTrue(ime.getMessage().contains("exceeds 5 seconds"), "Limit expected in message");
     }
 
     // Inspired by https://github.com/x-stream/xstream/commit/e8e88621ba1c85ac3b8620337dd672e0c0c3a846#diff-9fde4ecf1bb4dc9850c031cb161960d2e61e069b386fa0b3db0d57e0e9f5baa
@@ -161,7 +166,7 @@ public class RobustMapConverterTest {
     }
 
     @Test
-    public void robustAgainstInvalidEntry() {
+    void robustAgainstInvalidEntry() {
         RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS = true;
         XStream2 xstream2 = new XStream2();
         String xml =
@@ -181,7 +186,7 @@ public class RobustMapConverterTest {
     }
 
     @Test
-    public void robustAgainstInvalidEntryWithNoValue() {
+    void robustAgainstInvalidEntryWithNoValue() {
         XStream2 xstream2 = new XStream2();
         String xml =
             """
@@ -203,7 +208,7 @@ public class RobustMapConverterTest {
 
     @Issue("JENKINS-63343")
     @Test
-    public void robustAgainstInvalidKeyType() {
+    void robustAgainstInvalidKeyType() {
         XStream2 xstream2 = new XStream2();
         String xml =
             """
@@ -233,7 +238,7 @@ public class RobustMapConverterTest {
 
     @Issue("JENKINS-63343")
     @Test
-    public void robustAgainstInvalidValueType() {
+    void robustAgainstInvalidValueType() {
         XStream2 xstream2 = new XStream2();
         String xml =
             """
@@ -262,7 +267,7 @@ public class RobustMapConverterTest {
     }
 
     @Test
-    public void rawtypes() {
+    void rawtypes() {
         XStream2 xstream2 = new XStream2();
         String xml =
             """

core/src/test/java/hudson/util/RobustReflectionConverterTest.java

@@ -28,10 +28,10 @@ import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.equalTo;
 import static org.hamcrest.Matchers.instanceOf;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertNotNull;
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertNotNull;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import com.thoughtworks.xstream.XStream;
 import com.thoughtworks.xstream.converters.ConversionException;
@@ -51,38 +51,40 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Objects;
 import java.util.Set;
+import java.util.concurrent.TimeUnit;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import jenkins.util.xstream.CriticalXStreamException;
 import org.hamcrest.Matchers;
-import org.junit.After;
-import org.junit.Before;
-import org.junit.Ignore;
-import org.junit.Test;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.Timeout;
 import org.jvnet.hudson.test.Issue;
 
 /**
  * @author Kohsuke Kawaguchi
  */
-public class RobustReflectionConverterTest {
+class RobustReflectionConverterTest {
     private final boolean originalRecordFailures = RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS;
 
     static {
         Logger.getLogger(RobustReflectionConverter.class.getName()).setLevel(Level.OFF);
     }
 
-    @Before
-    public void before() {
+    @BeforeEach
+    void before() {
         RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS = true;
     }
 
-    @After
-    public void after() {
+    @AfterEach
+    void after() {
         RobustReflectionConverter.RECORD_FAILURES_FOR_ALL_AUTHENTICATIONS = originalRecordFailures;
     }
 
     @Test
-    public void robustUnmarshalling() {
+    void robustUnmarshalling() {
         Point p = read(new XStream2());
         assertEquals(1, p.x);
         assertEquals(2, p.y);
@@ -94,7 +96,7 @@ public class RobustReflectionConverterTest {
     }
 
     @Test
-    public void ifWorkaroundNeeded() {
+    void ifWorkaroundNeeded() {
         XStream xs = new XStream(XStream2.getDefaultDriver());
         xs.allowTypes(new Class[] {Point.class});
         final ConversionException e = assertThrows(ConversionException.class, () -> read(xs));
@@ -102,7 +104,7 @@ public class RobustReflectionConverterTest {
     }
 
     @Test
-    public void classOwnership() {
+    void classOwnership() {
         Enchufla s1 = new Enchufla();
         s1.number = 1;
         s1.direction = "North";
@@ -137,35 +139,37 @@ public class RobustReflectionConverterTest {
     }
 
     @Test
-    public void implicitCollection() {
+    void implicitCollection() {
         XStream2 xs = new XStream2();
         xs.alias("hold", Hold.class);
         xs.addImplicitCollection(Hold.class, "items", "item", String.class);
         Hold h = (Hold) xs.fromXML("<hold><item>a</item><item>b</item></hold>");
         assertThat(h.items, Matchers.containsInAnyOrder("a", "b"));
-        assertEquals("<hold>\n" +
-                "  <item>a</item>\n" +
-                "  <item>b</item>\n" +
-                "</hold>", xs.toXML(h));
+        assertEquals("""
+                <hold>
+                  <item>a</item>
+                  <item>b</item>
+                </hold>""", xs.toXML(h));
     }
 
-    @Ignore("Throws an NPE in writeValueToImplicitCollection. Issue has existed since RobustReflectionConverter was created.")
+    @Disabled("Throws an NPE in writeValueToImplicitCollection. Issue has existed since RobustReflectionConverter was created.")
     @Test
-    public void implicitCollectionsAllowNullElements() {
+    void implicitCollectionsAllowNullElements() {
         XStream2 xs = new XStream2();
         xs.alias("hold", Hold.class);
         xs.addImplicitCollection(Hold.class, "items", "item", String.class);
         Hold h = (Hold) xs.fromXML("<hold><null/><item>b</item></hold>");
         assertThat(h.items, Matchers.containsInAnyOrder(null, "b"));
-        assertEquals("<hold>\n" +
-                "  <null/>\n" +
-                "  <item>b</item>\n" +
-                "</hold>", xs.toXML(h));
+        assertEquals("""
+                <hold>
+                  <null/>
+                  <item>b</item>
+                </hold>""", xs.toXML(h));
     }
 
     @Issue("JENKINS-63343")
     @Test
-    public void robustAgainstImplicitCollectionElementsWithBadTypes() {
+    void robustAgainstImplicitCollectionElementsWithBadTypes() {
         XStream2 xs = new XStream2();
         xs.alias("hold", Hold.class);
         // Note that the fix only matters for `addImplicitCollection` overloads like the following where the element type is not provided.
@@ -186,13 +190,13 @@ public class RobustReflectionConverterTest {
         List<String> items;
 
         @Override
-        public void save() throws IOException {
+        public void save() {
             // We only implement Saveable so that RobustReflectionConverter logs deserialization problems.
         }
     }
 
     @Test
-    public void implicitCollectionRawtypes() {
+    void implicitCollectionRawtypes() {
         XStream2 xs = new XStream2();
         xs.alias("hold", HoldRaw.class);
         xs.addImplicitCollection(HoldRaw.class, "items");
@@ -259,9 +263,10 @@ public class RobustReflectionConverterTest {
     @Owner("p4")
     public static class Jean extends Lover {}
 
-    @Test(timeout = 30 * 1000)
+    @Test
+    @Timeout(value = 30 * 1000, unit = TimeUnit.MILLISECONDS)
     @Issue("SECURITY-2602")
-    public void robustDoesNotSwallowDosException() {
+    void robustDoesNotSwallowDosException() {
         XStream2 xstream2 = new XStream2();
 
         Set<Object> set = preparePayload();
@@ -280,11 +285,12 @@ public class RobustReflectionConverterTest {
         assertNotNull(cause);
         assertThat(cause, instanceOf(InputManipulationException.class));
         InputManipulationException ime = (InputManipulationException) cause;
-        assertTrue("Limit expected in message", ime.getMessage().contains("exceeds 5 seconds"));
+        assertTrue(ime.getMessage().contains("exceeds 5 seconds"), "Limit expected in message");
     }
 
-    @Test(timeout = 30 * 1000)
-    public void customConverter_useDefaultXStreamException() {
+    @Test
+    @Timeout(value = 30 * 1000, unit = TimeUnit.MILLISECONDS)
+    void customConverter_useDefaultXStreamException() {
         XStream2 xstream2 = new XStream2();
         xstream2.registerConverter(new CustomSet.ConverterImpl(xstream2.getMapper()));
 
@@ -294,12 +300,13 @@ public class RobustReflectionConverterTest {
         final String xml = xstream2.toXML(customSet);
 
         InputManipulationException e = assertThrows(InputManipulationException.class, () -> xstream2.fromXML(xml));
-        assertTrue("Limit expected in message", e.getMessage().contains("exceeds 5 seconds"));
+        assertTrue(e.getMessage().contains("exceeds 5 seconds"), "Limit expected in message");
     }
 
-    @Test(timeout = 30 * 1000)
+    @Test
+    @Timeout(value = 30 * 1000, unit = TimeUnit.MILLISECONDS)
     @Issue("SECURITY-2602")
-    public void customConverter_wrapped_useCriticalXStreamException() {
+    void customConverter_wrapped_useCriticalXStreamException() {
         XStream2 xstream2 = new XStream2();
         xstream2.registerConverter(new CustomSet.ConverterImpl(xstream2.getMapper())); // TODO Fix test so it does not pass without this
 
@@ -319,7 +326,7 @@ public class RobustReflectionConverterTest {
         assertNotNull(cause);
         assertThat(cause, instanceOf(InputManipulationException.class));
         InputManipulationException ime = (InputManipulationException) cause;
-        assertTrue("Limit expected in message", ime.getMessage().contains("exceeds 5 seconds"));
+        assertTrue(ime.getMessage().contains("exceeds 5 seconds"), "Limit expected in message");
     }
 
     private Set<Object> preparePayload() {

core/src/test/java/hudson/util/RunListTest.java

@@ -24,19 +24,19 @@
 
 package hudson.util;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 import hudson.model.Run;
 import java.util.ArrayList;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.jvnet.hudson.test.Issue;
 
 /**
  * @author Ignacio Albors
  */
-public class RunListTest {
+class RunListTest {
 
     // RunList for byTimestamp tests
     private RunList rlist;
@@ -60,7 +60,7 @@ public class RunListTest {
     }
 
     @Test
-    public void byTimestampAllRuns() {
+    void byTimestampAllRuns() {
         setUpByTimestampRuns();
 
         RunList<Run> tested = rlist.byTimestamp(0, 400);
@@ -70,7 +70,7 @@ public class RunListTest {
     @Issue("JENKINS-21159")
     @Test
     @SuppressWarnings("deprecation")
-    public void byTimestampFirstRun() {
+    void byTimestampFirstRun() {
         setUpByTimestampRuns();
         // Only r1
         RunList<Run> tested = rlist.byTimestamp(150, 250);
@@ -80,7 +80,7 @@ public class RunListTest {
 
     @Test
     @SuppressWarnings("deprecation")
-    public void byTimestampLastRun() {
+    void byTimestampLastRun() {
         setUpByTimestampRuns();
         // Only r2
         RunList<Run> tested = rlist.byTimestamp(250, 350);

core/src/test/java/hudson/util/SecretTest.java

@@ -27,10 +27,10 @@ package hudson.util;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.not;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotEquals;
-import static org.junit.Assert.assertTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import java.nio.charset.StandardCharsets;
 import java.util.Base64;
@@ -39,19 +39,21 @@ import java.util.regex.Pattern;
 import javax.crypto.Cipher;
 import javax.crypto.SecretKey;
 import jenkins.model.Jenkins;
-import jenkins.security.ConfidentialStoreRule;
-import org.junit.Rule;
-import org.junit.Test;
+import jenkins.security.ConfidentialStore;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
 
-public class SecretTest {
-
-    @Rule
-    public ConfidentialStoreRule confidentialStore = new ConfidentialStoreRule();
+class SecretTest {
 
     private static final Pattern ENCRYPTED_VALUE_PATTERN = Pattern.compile("\\{?[A-Za-z0-9+/]+={0,2}}?");
 
+    @BeforeEach
+    void setUp() {
+        ConfidentialStore.Mock.INSTANCE.clear();
+    }
+
     @Test
-    public void encrypt() {
+    void encrypt() {
         Secret secret = Secret.fromString("abc");
         assertEquals("abc", secret.getPlainText());
 
@@ -68,7 +70,7 @@ public class SecretTest {
     }
 
     @Test
-    public void encryptedValuePattern() {
+    void encryptedValuePattern() {
         final Random random = new Random();
         for (int i = 1; i < 100; i++) {
             String plaintext = random(i, random);
@@ -95,20 +97,20 @@ public class SecretTest {
     }
 
     @Test
-    public void decrypt() {
+    void decrypt() {
         assertEquals("abc", Secret.toString(Secret.fromString("abc")));
     }
 
     @Test
-    public void serialization() {
+    void serialization() {
         Secret s = Secret.fromString("Mr.Jenkins");
         String xml = Jenkins.XSTREAM.toXML(s);
         assertThat(xml, not(containsString(s.getPlainText())));
         // TODO MatchesPattern not available until Hamcrest 2.0
-        assertTrue(xml, xml.matches("<hudson[.]util[.]Secret>[{][A-Za-z0-9+/]+={0,2}[}]</hudson[.]util[.]Secret>"));
+        assertTrue(xml.matches("<hudson[.]util[.]Secret>[{][A-Za-z0-9+/]+={0,2}[}]</hudson[.]util[.]Secret>"), xml);
 
         Object o = Jenkins.XSTREAM.fromXML(xml);
-        assertEquals(xml, s, o);
+        assertEquals(s, o, xml);
     }
 
     public static class Foo {
@@ -119,7 +121,7 @@ public class SecretTest {
      * Makes sure the serialization form is backward compatible with String.
      */
     @Test
-    public void testCompatibilityFromString() {
+    void testCompatibilityFromString() {
         String tagName = Foo.class.getName().replace("$", "_-");
         String xml = "<" + tagName + "><password>secret</password></" + tagName + ">";
         Foo foo = new Foo();
@@ -132,15 +134,15 @@ public class SecretTest {
      */
     @Test
     @SuppressWarnings("deprecation")
-    public void migrationFromLegacyKeyToConfidentialStore() throws Exception {
+    void migrationFromLegacyKeyToConfidentialStore() throws Exception {
         SecretKey legacy = HistoricalSecrets.getLegacyKey();
         for (String str : new String[] {"Hello world", "", "\u0000unprintable"}) {
             Cipher cipher = Secret.getCipher("AES");
             cipher.init(Cipher.ENCRYPT_MODE, legacy);
             String old = Base64.getEncoder().encodeToString(cipher.doFinal((str + HistoricalSecrets.MAGIC).getBytes(StandardCharsets.UTF_8)));
             Secret s = Secret.fromString(old);
-            assertEquals("secret by the old key should decrypt", str, s.getPlainText());
-            assertNotEquals("but when encrypting, ConfidentialKey should be in use", old, s.getEncryptedValue());
+            assertEquals(str, s.getPlainText(), "secret by the old key should decrypt");
+            assertNotEquals(old, s.getEncryptedValue(), "but when encrypting, ConfidentialKey should be in use");
         }
     }
 

core/src/test/java/hudson/util/SecretUtilTest.java

@@ -1,41 +1,42 @@
 package hudson.util;
 
-import org.junit.Assert;
-import org.junit.Test;
+import static org.junit.jupiter.api.Assertions.assertNull;
+
+import org.junit.jupiter.api.Test;
 import org.jvnet.hudson.test.Issue;
 
-public class SecretUtilTest {
+class SecretUtilTest {
 
     @Issue("JENKINS-47500")
     @Test
-    public void decrypt() {
+    void decrypt() {
         String data = "{}";
         Secret secret = Secret.decrypt(data);
-        Assert.assertNull(secret); // expected to not throw ArrayIndexOutOfBoundsException
+        assertNull(secret); // expected to not throw ArrayIndexOutOfBoundsException
     }
 
 
     @Issue("JENKINS-47500")
     @Test
-    public void decryptJustSpace() {
+    void decryptJustSpace() {
         String data = " ";
         Secret secret = Secret.decrypt(data);
-        Assert.assertNull(secret); // expected to not throw ArrayIndexOutOfBoundsException
+        assertNull(secret); // expected to not throw ArrayIndexOutOfBoundsException
     }
 
     @Issue("JENKINS-47500")
     @Test
-    public void decryptWithSpace() {
+    void decryptWithSpace() {
         String data = "{ }";
         Secret secret = Secret.decrypt(data);
-        Assert.assertNull(secret); // expected to not throw ArrayIndexOutOfBoundsException
+        assertNull(secret); // expected to not throw ArrayIndexOutOfBoundsException
     }
 
     @Issue("JENKINS-47500")
     @Test
-    public void decryptWithSpaces() {
+    void decryptWithSpaces() {
         String data = "{     }";
         Secret secret = Secret.decrypt(data);
-        Assert.assertNull(secret); // expected to not throw ArrayIndexOutOfBoundsException
+        assertNull(secret); // expected to not throw ArrayIndexOutOfBoundsException
     }
 }

core/src/test/java/hudson/util/TextFileTest.java

@@ -1,6 +1,6 @@
 package hudson.util;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
 
 import java.io.File;
 import java.io.FileOutputStream;
@@ -8,18 +8,17 @@ import java.io.OutputStream;
 import java.nio.charset.Charset;
 import java.nio.file.Files;
 import org.apache.commons.io.FileUtils;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 
-public class TextFileTest {
+class TextFileTest {
 
-    @Rule
-    public TemporaryFolder tmp = new TemporaryFolder();
+    @TempDir
+    private File tmp;
 
     @Test
-    public void head() throws Exception {
-        File f = tmp.newFile();
+    void head() throws Exception {
+        File f = File.createTempFile("junit", null, tmp);
         FileUtils.copyURLToFile(getClass().getResource("ascii.txt"), f);
 
         TextFile t = new TextFile(f);
@@ -29,8 +28,8 @@ public class TextFileTest {
     }
 
     @Test
-    public void shortHead() throws Exception {
-        File f = tmp.newFile();
+    void shortHead() throws Exception {
+        File f = File.createTempFile("junit", null, tmp);
         Files.writeString(f.toPath(), "hello", Charset.defaultCharset());
 
         TextFile t = new TextFile(f);
@@ -38,8 +37,8 @@ public class TextFileTest {
     }
 
     @Test
-    public void tail() throws Exception {
-        File f = tmp.newFile();
+    void tail() throws Exception {
+        File f = File.createTempFile("junit", null, tmp);
         FileUtils.copyURLToFile(getClass().getResource("ascii.txt"), f);
         String whole = Files.readString(f.toPath(), Charset.defaultCharset());
         TextFile t = new TextFile(f);
@@ -48,8 +47,8 @@ public class TextFileTest {
     }
 
     @Test
-    public void shortTail() throws Exception {
-        File f = tmp.newFile();
+    void shortTail() throws Exception {
+        File f = File.createTempFile("junit", null, tmp);
         Files.writeString(f.toPath(), "hello", Charset.defaultCharset());
 
         TextFile t = new TextFile(f);
@@ -63,8 +62,8 @@ public class TextFileTest {
      * careful, we'll parse the text incorrectly.
      */
     @Test
-    public void tailShiftJIS() throws Exception {
-        File f = tmp.newFile();
+    void tailShiftJIS() throws Exception {
+        File f = File.createTempFile("junit", null, tmp);
 
         TextFile t = new TextFile(f);
 

core/src/test/java/hudson/util/XStream2EncodingTest.java

@@ -27,25 +27,24 @@ package hudson.util;
 import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.is;
 import static org.hamcrest.Matchers.not;
-import static org.junit.Assume.assumeNoException;
-import static org.junit.Assume.assumeThat;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
 
 import java.io.ByteArrayInputStream;
 import java.io.ByteArrayOutputStream;
 import java.lang.reflect.Field;
 import java.nio.charset.Charset;
 import java.nio.charset.StandardCharsets;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
 /**
  * In its own suite to minimize the chance of mucking about with other tests.
  */
-public class XStream2EncodingTest {
+class XStream2EncodingTest {
 
     private static void useNonUTF8() {
         clearDefaultEncoding();
         System.setProperty("file.encoding", "ISO-8859-1");
-        assumeThat(Charset.defaultCharset().name(), is("ISO-8859-1"));
+        assumeTrue(Charset.defaultCharset().name().equals("ISO-8859-1"));
     }
 
     private static void clearDefaultEncodingAfter() {
@@ -59,12 +58,13 @@ public class XStream2EncodingTest {
             defaultCharset.set(null, null);
         } catch (Exception x) {
             // Per JDK-4163515, this is not supported. It happened to work prior to Java 17, though.
-            assumeNoException(x);
+            assumeTrue(false, x.toString());
         }
     }
 
     @SuppressWarnings("deprecation")
-    @Test public void toXMLUnspecifiedEncoding() throws Exception {
+    @Test
+    void toXMLUnspecifiedEncoding() throws Exception {
       useNonUTF8();
       try {
         ByteArrayOutputStream baos = new ByteArrayOutputStream();
@@ -84,7 +84,8 @@ public class XStream2EncodingTest {
       }
     }
 
-    @Test public void toXMLUTF8() throws Exception {
+    @Test
+    void toXMLUTF8() throws Exception {
       useNonUTF8();
       try {
         ByteArrayOutputStream baos = new ByteArrayOutputStream();

core/src/test/java/hudson/util/XStream2Test.java

@@ -28,12 +28,12 @@ import static org.hamcrest.MatcherAssert.assertThat;
 import static org.hamcrest.Matchers.containsString;
 import static org.hamcrest.Matchers.instanceOf;
 import static org.hamcrest.Matchers.is;
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertSame;
-import static org.junit.Assert.assertThrows;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assert.fail;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertSame;
+import static org.junit.jupiter.api.Assertions.assertThrows;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assertions.fail;
 
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -55,26 +55,26 @@ import java.util.concurrent.ConcurrentHashMap;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 import jenkins.model.Jenkins;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 import org.jvnet.hudson.test.Issue;
 
 /**
  * Tests for XML serialization of java objects.
  * @author Kohsuke Kawaguchi, Mike Dillon, Alan Harder, Richard Mortimer
  */
-public class XStream2Test {
+class XStream2Test {
 
     public static final class Foo {
         Result r1, r2;
     }
 
     @Test
-    public void marshalValue() {
+    void marshalValue() {
         Foo f = new Foo();
         f.r1 = f.r2 = Result.FAILURE;
         String xml = Run.XSTREAM.toXML(f);
         // we should find two "FAILURE"s as they should be written out twice
-        assertEquals(xml, 3, xml.split("FAILURE").length);
+        assertEquals(3, xml.split("FAILURE").length, xml);
     }
 
     private static class Bar {
@@ -85,7 +85,7 @@ public class XStream2Test {
      * Test ability to read old XML from Hudson 1.105 or older.
      */
     @Test
-    public void xStream11Compatibility() {
+    void xStream11Compatibility() {
         Bar b = (Bar) new XStream2().fromXML(
                 "<hudson.util.XStream2Test-Bar><s>foo</s></hudson.util.XStream2Test-Bar>");
         assertEquals("foo", b.s);
@@ -102,19 +102,19 @@ public class XStream2Test {
      */
     @Issue("JENKINS-5768")
     @Test
-    public void xmlRoundTrip() {
+    void xmlRoundTrip() {
         XStream2 xs = new XStream2();
         __Foo_Bar$Class b = new __Foo_Bar$Class();
 
         String xml = xs.toXML(b);
         __Foo_Bar$Class b2 = (__Foo_Bar$Class) xs.fromXML(xml);
 
-        assertEquals(xml, b.under_1, b2.under_1);
-        assertEquals(xml, b.under__2, b2.under__2);
-        assertEquals(xml, b._leadUnder1, b2._leadUnder1);
-        assertEquals(xml, b.__leadUnder2, b2.__leadUnder2);
-        assertEquals(xml, b.$dollar, b2.$dollar);
-        assertEquals(xml, b.dollar$2, b2.dollar$2);
+        assertEquals(b.under_1, b2.under_1, xml);
+        assertEquals(b.under__2, b2.under__2, xml);
+        assertEquals(b._leadUnder1, b2._leadUnder1, xml);
+        assertEquals(b.__leadUnder2, b2.__leadUnder2, xml);
+        assertEquals(b.$dollar, b2.$dollar, xml);
+        assertEquals(b.dollar$2, b2.dollar$2, xml);
     }
 
     private static class Baz {
@@ -128,7 +128,7 @@ public class XStream2Test {
      */
     @Issue("JENKINS-5769")
     @Test
-    public void unmarshalThrowableMissingField() {
+    void unmarshalThrowableMissingField() {
         Level oldLevel = disableLogging();
 
         Baz baz = new Baz();
@@ -171,7 +171,7 @@ public class XStream2Test {
     }
 
     @Test
-    public void immutableMap() {
+    void immutableMap() {
         XStream2 xs = new XStream2();
 
         roundtripImmutableMap(xs, ImmutableMap.of());
@@ -191,8 +191,8 @@ public class XStream2Test {
         a.m = m;
         String xml = xs.toXML(a);
         //System.out.println(xml);
-        assertFalse("shouldn't contain the class name", xml.contains("google"));
-        assertFalse("shouldn't contain the class name", xml.contains("class"));
+        assertFalse(xml.contains("google"), "shouldn't contain the class name");
+        assertFalse(xml.contains("class"), "shouldn't contain the class name");
         a = (ImmutableMapHolder) xs.fromXML(xml);
 
         assertSame(m.getClass(), a.m.getClass());    // should get back the exact same type, not just a random map
@@ -204,7 +204,7 @@ public class XStream2Test {
         a.m = m;
         String xml = xs.toXML(a);
         //System.out.println(xml);
-        assertTrue("XML should mention the class name", xml.contains('\"' + ImmutableMap.class.getName() + '\"'));
+        assertTrue(xml.contains('\"' + ImmutableMap.class.getName() + '\"'), "XML should mention the class name");
         a = (MapHolder) xs.fromXML(xml);
 
         assertSame(m.getClass(), a.m.getClass());    // should get back the exact same type, not just a random map
@@ -220,7 +220,7 @@ public class XStream2Test {
     }
 
     @Test
-    public void immutableList() {
+    void immutableList() {
         XStream2 xs = new XStream2();
 
         roundtripImmutableList(xs, ImmutableList.of());
@@ -240,8 +240,8 @@ public class XStream2Test {
         a.l = l;
         String xml = xs.toXML(a);
         //System.out.println(xml);
-        assertFalse("shouldn't contain the class name", xml.contains("google"));
-        assertFalse("shouldn't contain the class name", xml.contains("class"));
+        assertFalse(xml.contains("google"), "shouldn't contain the class name");
+        assertFalse(xml.contains("class"), "shouldn't contain the class name");
         a = (ImmutableListHolder) xs.fromXML(xml);
 
         assertSame(l.getClass(), a.l.getClass());    // should get back the exact same type, not just a random list
@@ -253,7 +253,7 @@ public class XStream2Test {
         a.l = l;
         String xml = xs.toXML(a);
         //System.out.println(xml);
-        assertTrue("XML should mention the class name", xml.contains('\"' + ImmutableList.class.getName() + '\"'));
+        assertTrue(xml.contains('\"' + ImmutableList.class.getName() + '\"'), "XML should mention the class name");
         a = (ListHolder) xs.fromXML(xml);
 
         assertSame(l.getClass(), a.l.getClass());    // should get back the exact same type, not just a random list
@@ -262,14 +262,14 @@ public class XStream2Test {
 
     @Issue("JENKINS-8006") // Previously a null entry in an array caused NPE
     @Test
-    public void emptyStack() {
+    void emptyStack() {
         assertEquals("<object-array><null/><null/></object-array>",
                      Run.XSTREAM.toXML(new Object[2]).replaceAll("[ \n\r\t]+", ""));
     }
 
     @Issue("JENKINS-9843")
     @Test
-    public void compatibilityAlias() {
+    void compatibilityAlias() {
         XStream2 xs = new XStream2();
         xs.addCompatibilityAlias("legacy.Point", Point.class);
         Point pt = (Point) xs.fromXML("<legacy.Point><x>1</x><y>2</y></legacy.Point>");
@@ -277,7 +277,7 @@ public class XStream2Test {
         assertEquals(2, pt.y);
         String xml = xs.toXML(pt);
         //System.out.println(xml);
-        assertFalse("Shouldn't use the alias when writing back", xml.contains("legacy"));
+        assertFalse(xml.contains("legacy"), "Shouldn't use the alias when writing back");
     }
 
     public static class Point {
@@ -290,7 +290,7 @@ public class XStream2Test {
 
     @Issue("SECURITY-105")
     @Test
-    public void dynamicProxyBlocked() {
+    void dynamicProxyBlocked() {
         assertThrows(
                 XStreamException.class,
                 () -> ((Runnable) new XStream2().fromXML(
@@ -298,7 +298,7 @@ public class XStream2Test {
                                         + Hacked.class.getName()
                                         + "'/><action>oops</action></handler></dynamic-proxy>"))
                         .run());
-        assertFalse("should never have run that", Hacked.tripped);
+        assertFalse(Hacked.tripped, "should never have run that");
     }
 
     public static final class Hacked {
@@ -310,7 +310,7 @@ public class XStream2Test {
     }
 
     @Test
-    public void trimVersion() {
+    void trimVersion() {
         assertEquals("3.2", XStream2.trimVersion("3.2"));
         assertEquals("3.2.1", XStream2.trimVersion("3.2.1"));
         assertEquals("3.2-SNAPSHOT", XStream2.trimVersion("3.2-SNAPSHOT (private-09/23/2012 12:26-jhacker)"));
@@ -318,41 +318,42 @@ public class XStream2Test {
 
     @Issue("JENKINS-21017")
     @Test
-    public void unmarshalToDefault_populated() {
-        String populatedXml = "<hudson.util.XStream2Test_-WithDefaults>\n"
-                + "  <stringDefaultValue>my string</stringDefaultValue>\n"
-                + "  <stringDefaultNull>not null</stringDefaultNull>\n"
-                + "  <arrayDefaultValue>\n"
-                + "    <string>1</string>\n"
-                + "    <string>2</string>\n"
-                + "    <string>3</string>\n"
-                + "  </arrayDefaultValue>\n"
-                + "  <arrayDefaultEmpty>\n"
-                + "    <string>1</string>\n"
-                + "    <string>2</string>\n"
-                + "    <string>3</string>\n"
-                + "  </arrayDefaultEmpty>\n"
-                + "  <arrayDefaultNull>\n"
-                + "    <string>1</string>\n"
-                + "    <string>2</string>\n"
-                + "    <string>3</string>\n"
-                + "  </arrayDefaultNull>\n"
-                + "  <listDefaultValue>\n"
-                + "    <string>1</string>\n"
-                + "    <string>2</string>\n"
-                + "    <string>3</string>\n"
-                + "  </listDefaultValue>\n"
-                + "  <listDefaultEmpty>\n"
-                + "    <string>1</string>\n"
-                + "    <string>2</string>\n"
-                + "    <string>3</string>\n"
-                + "  </listDefaultEmpty>\n"
-                + "  <listDefaultNull>\n"
-                + "    <string>1</string>\n"
-                + "    <string>2</string>\n"
-                + "    <string>3</string>\n"
-                + "  </listDefaultNull>\n"
-                + "</hudson.util.XStream2Test_-WithDefaults>";
+    void unmarshalToDefault_populated() {
+        String populatedXml = """
+                <hudson.util.XStream2Test_-WithDefaults>
+                  <stringDefaultValue>my string</stringDefaultValue>
+                  <stringDefaultNull>not null</stringDefaultNull>
+                  <arrayDefaultValue>
+                    <string>1</string>
+                    <string>2</string>
+                    <string>3</string>
+                  </arrayDefaultValue>
+                  <arrayDefaultEmpty>
+                    <string>1</string>
+                    <string>2</string>
+                    <string>3</string>
+                  </arrayDefaultEmpty>
+                  <arrayDefaultNull>
+                    <string>1</string>
+                    <string>2</string>
+                    <string>3</string>
+                  </arrayDefaultNull>
+                  <listDefaultValue>
+                    <string>1</string>
+                    <string>2</string>
+                    <string>3</string>
+                  </listDefaultValue>
+                  <listDefaultEmpty>
+                    <string>1</string>
+                    <string>2</string>
+                    <string>3</string>
+                  </listDefaultEmpty>
+                  <listDefaultNull>
+                    <string>1</string>
+                    <string>2</string>
+                    <string>3</string>
+                  </listDefaultNull>
+                </hudson.util.XStream2Test_-WithDefaults>""";
 
         WithDefaults existingInstance = new WithDefaults("foobar",
                 "foobar",
@@ -377,20 +378,21 @@ public class XStream2Test {
 
     @Issue("JENKINS-21017")
     @Test
-    public void unmarshalToDefault_default() {
-        String defaultXml = "<hudson.util.XStream2Test_-WithDefaults>\n"
-                + "  <stringDefaultValue>defaultValue</stringDefaultValue>\n"
-                + "  <arrayDefaultValue>\n"
-                + "    <string>first</string>\n"
-                + "    <string>second</string>\n"
-                + "  </arrayDefaultValue>\n"
-                + "  <arrayDefaultEmpty/>\n"
-                + "  <listDefaultValue>\n"
-                + "    <string>first</string>\n"
-                + "    <string>second</string>\n"
-                + "  </listDefaultValue>\n"
-                + "  <listDefaultEmpty/>\n"
-                + "</hudson.util.XStream2Test_-WithDefaults>";
+    void unmarshalToDefault_default() {
+        String defaultXml = """
+                <hudson.util.XStream2Test_-WithDefaults>
+                  <stringDefaultValue>defaultValue</stringDefaultValue>
+                  <arrayDefaultValue>
+                    <string>first</string>
+                    <string>second</string>
+                  </arrayDefaultValue>
+                  <arrayDefaultEmpty/>
+                  <listDefaultValue>
+                    <string>first</string>
+                    <string>second</string>
+                  </listDefaultValue>
+                  <listDefaultEmpty/>
+                </hudson.util.XStream2Test_-WithDefaults>""";
 
         WithDefaults existingInstance = new WithDefaults("foobar",
                 "foobar",
@@ -415,7 +417,7 @@ public class XStream2Test {
 
     @Issue("JENKINS-21017")
     @Test
-    public void unmarshalToDefault_empty() {
+    void unmarshalToDefault_empty() {
         String emptyXml = "<hudson.util.XStream2Test_-WithDefaults/>";
 
         WithDefaults existingInstance = new WithDefaults("foobar",
@@ -455,9 +457,11 @@ public class XStream2Test {
         private List<String> listDefaultEmpty = new ArrayList<>();
         private List<String> listDefaultNull;
 
+        @SuppressWarnings("checkstyle:redundantmodifier")
         public WithDefaults() {
         }
 
+        @SuppressWarnings("checkstyle:redundantmodifier")
         public WithDefaults(String stringDefaultValue, String stringDefaultNull, String[] arrayDefaultValue,
                             String[] arrayDefaultEmpty, String[] arrayDefaultNull,
                             List<String> listDefaultValue, List<String> listDefaultEmpty,
@@ -539,15 +543,15 @@ public class XStream2Test {
 
     @Issue("SECURITY-503")
     @Test
-    public void crashXstream() {
+    void crashXstream() {
         assertThrows(XStreamException.class, () -> new XStream2().fromXML("<void/>"));
     }
 
     @Test
-    public void annotations() {
-        assertEquals("not registered, so sorry", "<hudson.util.XStream2Test_-C1/>", Jenkins.XSTREAM2.toXML(new C1()));
-        assertEquals("manually registered", "<C-2/>", Jenkins.XSTREAM2.toXML(new C2()));
-        assertEquals("manually processed", "<C-3/>", Jenkins.XSTREAM2.toXML(new C3()));
+    void annotations() {
+        assertEquals("<hudson.util.XStream2Test_-C1/>", Jenkins.XSTREAM2.toXML(new C1()), "not registered, so sorry");
+        assertEquals("<C-2/>", Jenkins.XSTREAM2.toXML(new C2()), "manually registered");
+        assertEquals("<C-3/>", Jenkins.XSTREAM2.toXML(new C3()), "manually processed");
         assertThrows(CannotResolveClassException.class, () -> Jenkins.XSTREAM2.fromXML("<C-4/>"));
 
         Jenkins.XSTREAM2.processAnnotations(C5.class);
@@ -578,7 +582,7 @@ public class XStream2Test {
 
     @Issue("JENKINS-69129")
     @Test
-    public void testEmoji() throws Exception {
+    void testEmoji() throws Exception {
         Bar bar;
         try (InputStream is = getClass().getResource("XStream2Emoji.xml").openStream()) {
             bar = (Bar) new XStream2().fromXML(is);
@@ -588,7 +592,7 @@ public class XStream2Test {
 
     @Issue("JENKINS-69129")
     @Test
-    public void testEmojiEscaped() throws Exception {
+    void testEmojiEscaped() throws Exception {
         Bar bar;
         try (InputStream is = getClass().getResource("XStream2EmojiEscaped.xml").openStream()) {
             bar = (Bar) new XStream2().fromXML(is);
@@ -598,7 +602,7 @@ public class XStream2Test {
 
     @Issue("JENKINS-71182")
     @Test
-    public void writeEmoji() throws Exception {
+    void writeEmoji() {
         Bar b = new Bar();
         String text = "Fox 🦊";
         b.s = text;
@@ -613,7 +617,7 @@ public class XStream2Test {
 
     @Issue("JENKINS-71139")
     @Test
-    public void nullsWithoutEncodingDeclaration() throws Exception {
+    void nullsWithoutEncodingDeclaration() {
         Bar b = new Bar();
         b.s = "x\u0000y";
         try {
@@ -626,7 +630,7 @@ public class XStream2Test {
 
     @Issue("JENKINS-71139")
     @Test
-    public void nullsWithEncodingDeclaration() throws Exception {
+    void nullsWithEncodingDeclaration() throws Exception {
         Bar b = new Bar();
         b.s = "x\u0000y";
         try {

core/src/test/java/hudson/util/io/RewindableRotatingFileOutputStreamTest.java

@@ -1,8 +1,8 @@
 package hudson.util.io;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assume.assumeFalse;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assumptions.assumeFalse;
 
 import hudson.FilePath;
 import hudson.Functions;
@@ -12,19 +12,18 @@ import java.io.OutputStreamWriter;
 import java.io.PrintWriter;
 import java.nio.charset.StandardCharsets;
 import org.apache.commons.io.FileUtils;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.jvnet.hudson.test.Issue;
 
-public class RewindableRotatingFileOutputStreamTest {
+class RewindableRotatingFileOutputStreamTest {
 
-    @Rule
-    public TemporaryFolder tmp = new TemporaryFolder();
+    @TempDir
+    private File tmp;
 
     @Test
-    public void rotation() throws IOException, InterruptedException {
-        File base = tmp.newFile("test.log");
+    void rotation() throws IOException, InterruptedException {
+        File base = File.createTempFile("test.log", null, tmp);
         RewindableRotatingFileOutputStream os = new RewindableRotatingFileOutputStream(base, 3);
         PrintWriter w = new PrintWriter(new OutputStreamWriter(os, StandardCharsets.UTF_8), true);
         for (int i = 0; i <= 4; i++) {
@@ -45,10 +44,10 @@ public class RewindableRotatingFileOutputStreamTest {
 
     @Issue("JENKINS-16634")
     @Test
-    public void deletedFolder() throws Exception {
-        assumeFalse("Windows does not allow deleting a directory with a "
-            + "file open, so this case should never occur", Functions.isWindows());
-        File dir = tmp.newFolder("dir");
+    void deletedFolder() throws Exception {
+        assumeFalse(Functions.isWindows(), "Windows does not allow deleting a directory with a "
+            + "file open, so this case should never occur");
+        File dir = newFolder(tmp, "dir");
         File base = new File(dir, "x.log");
         RewindableRotatingFileOutputStream os = new RewindableRotatingFileOutputStream(base, 3);
         for (int i = 0; i < 2; i++) {
@@ -61,4 +60,13 @@ public class RewindableRotatingFileOutputStreamTest {
         }
     }
 
+    private static File newFolder(File root, String... subDirs) throws IOException {
+        String subFolder = String.join("/", subDirs);
+        File result = new File(root, subFolder);
+        if (!result.mkdirs()) {
+            throw new IOException("Couldn't create folders " + root);
+        }
+        return result;
+    }
+
 }

core/src/test/java/hudson/util/io/TarArchiverTest.java

@@ -24,9 +24,9 @@
 
 package hudson.util.io;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assume.assumeFalse;
-import static org.junit.Assume.assumeNoException;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assumptions.assumeFalse;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
 
 import hudson.FilePath;
 import hudson.Functions;
@@ -46,21 +46,22 @@ import java.util.HashSet;
 import java.util.Set;
 import org.apache.tools.tar.TarEntry;
 import org.apache.tools.tar.TarInputStream;
-import org.junit.Ignore;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.jvnet.hudson.test.Issue;
 
-public class TarArchiverTest {
+class TarArchiverTest {
 
-    @Rule public TemporaryFolder tmp = new TemporaryFolder();
+    @TempDir
+    private File tmp;
 
     /**
      * Makes sure that permissions are properly stored in the tar file.
      */
     @Issue("JENKINS-9397")
-    @Test public void permission() throws Exception {
+    @Test
+    void permission() throws Exception {
         assumeFalse(Functions.isWindows());
 
         File tar = File.createTempFile("test", "tar");
@@ -115,26 +116,27 @@ public class TarArchiverTest {
         try {
             assertEquals(0, new LocalLauncher(StreamTaskListener.fromStdout()).launch().cmds(cmds).pwd(dir).join());
         } catch (IOException x) { // perhaps restrict to x.message.contains("Cannot run program")? or "error=2, No such file or directory"?
-            assumeNoException("failed to run " + Arrays.toString(cmds), x);
+            assumeTrue(false, "failed to run " + Arrays.toString(cmds) + ": " + x);
         }
     }
 
     @Issue("JENKINS-14922")
-    @Test public void brokenSymlinks() throws Exception {
+    @Test
+    void brokenSymlinks() throws Exception {
         assumeFalse(Functions.isWindows());
-        File dir = tmp.getRoot();
+        File dir = tmp;
         Util.createSymlink(dir, "nonexistent", "link", TaskListener.NULL);
         try (OutputStream out = OutputStream.nullOutputStream()) {
             new FilePath(dir).tar(out, "**");
         }
     }
 
-    @Ignore("TODO fails to add empty directories to archive")
+    @Disabled("TODO fails to add empty directories to archive")
     @Issue("JENKINS-73837")
     @Test
-    public void emptyDirectory() throws Exception {
-        Path tar = tmp.newFile("test.tar").toPath();
-        Path root = tmp.newFolder().toPath();
+    void emptyDirectory() throws Exception {
+        Path tar = File.createTempFile("test.tar", null, tmp).toPath();
+        Path root = newFolder(tmp, "junit").toPath();
         Files.createDirectory(root.resolve("foo"));
         Files.createDirectory(root.resolve("bar"));
         Files.writeString(root.resolve("bar/file.txt"), "foobar", StandardCharsets.UTF_8);
@@ -157,14 +159,15 @@ public class TarArchiverTest {
      */
 
     @Issue("JENKINS-20187")
-    @Test public void growingFileTar() throws Exception {
-        File file = new File(tmp.getRoot(), "growing.file");
+    @Test
+    void growingFileTar() throws Exception {
+        File file = new File(tmp, "growing.file");
         GrowingFileRunnable runnable1 = new GrowingFileRunnable(file);
         Thread t1 = new Thread(runnable1);
         t1.start();
 
         try (OutputStream out = OutputStream.nullOutputStream()) {
-            new FilePath(tmp.getRoot()).tar(out, "**");
+            new FilePath(tmp).tar(out, "**");
         }
 
         runnable1.doFinish();
@@ -204,4 +207,13 @@ public class TarArchiverTest {
         }
     }
 
+    private static File newFolder(File root, String... subDirs) throws IOException {
+        String subFolder = String.join("/", subDirs);
+        File result = new File(root, subFolder);
+        if (!result.mkdirs()) {
+            throw new IOException("Couldn't create folders " + root);
+        }
+        return result;
+    }
+
 }

core/src/test/java/hudson/util/io/ZipArchiverTest.java

@@ -1,8 +1,10 @@
 package hudson.util.io;
 
-import static org.junit.Assert.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
 
 import hudson.FilePath;
+import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
@@ -15,28 +17,27 @@ import java.util.Set;
 import java.util.zip.ZipEntry;
 import java.util.zip.ZipFile;
 import java.util.zip.ZipInputStream;
-import org.junit.Assume;
-import org.junit.Ignore;
-import org.junit.Rule;
-import org.junit.Test;
-import org.junit.rules.TemporaryFolder;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
 import org.jvnet.hudson.test.Issue;
 
-public class ZipArchiverTest {
+class ZipArchiverTest {
 
-    @Rule public TemporaryFolder tmp = new TemporaryFolder();
+    @TempDir
+    private File tmp;
 
     @Issue("JENKINS-9942")
     @Test
-    public void backwardsSlashesOnWindows() throws IOException {
+    void backwardsSlashesOnWindows() throws IOException {
         // create foo/bar/baz/Test.txt
-        Path baz = tmp.newFolder().toPath().resolve("foo").resolve("bar").resolve("baz");
+        Path baz = newFolder(tmp, "junit").toPath().resolve("foo").resolve("bar").resolve("baz");
         Files.createDirectories(baz);
         Path tmpFile = baz.resolve("Test.txt");
         Files.createFile(tmpFile);
 
         // a file to store the zip archive in
-        Path zipFile = Files.createTempFile(tmp.getRoot().toPath(), "test", ".zip");
+        Path zipFile = Files.createTempFile(tmp.toPath(), "test", ".zip");
 
         // create zip from tmpDir
         try (ZipArchiver archiver = new ZipArchiver(Files.newOutputStream(zipFile))) {
@@ -53,19 +54,19 @@ public class ZipArchiverTest {
     }
 
     @Test
-    public void huge64bitFile() throws IOException {
+    void huge64bitFile() throws IOException {
         // create huge64bitFileTest.txt
-        Path hugeFile = tmp.newFolder().toPath().resolve("huge64bitFileTest.txt");
+        Path hugeFile = newFolder(tmp, "junit").toPath().resolve("huge64bitFileTest.txt");
         long length = 4L * 1024 * 1024 * 1024 + 2;
         try (RandomAccessFile largeFile = new RandomAccessFile(hugeFile.toFile(), "rw")) {
             largeFile.setLength(length);
         } catch (IOException e) {
             // We probably don't have enough free disk space. That's ok, we'll skip this test...
-            Assume.assumeNoException(e);
+            assumeTrue(false, e.toString());
         }
 
         // a file to store the zip archive in
-        Path zipFile = Files.createTempFile(tmp.getRoot().toPath(), "test", ".zip");
+        Path zipFile = Files.createTempFile(tmp.toPath(), "test", ".zip");
 
         // create zip from tmpDir
         try (ZipArchiver archiver = new ZipArchiver(Files.newOutputStream(zipFile))) {
@@ -81,12 +82,12 @@ public class ZipArchiverTest {
         }
     }
 
-    @Ignore("TODO fails to add empty directories to archive")
+    @Disabled("TODO fails to add empty directories to archive")
     @Issue("JENKINS-49296")
     @Test
-    public void emptyDirectory() throws Exception {
-        Path zip = tmp.newFile("test.zip").toPath();
-        Path root = tmp.newFolder().toPath();
+    void emptyDirectory() throws Exception {
+        Path zip = File.createTempFile("test.zip", null, tmp).toPath();
+        Path root = newFolder(tmp, "junit").toPath();
         Files.createDirectory(root.resolve("foo"));
         Files.createDirectory(root.resolve("bar"));
         Files.writeString(root.resolve("bar/file.txt"), "foobar", StandardCharsets.UTF_8);
@@ -103,4 +104,13 @@ public class ZipArchiverTest {
         }
         assertEquals(Set.of("foo/", "bar/", "bar/file.txt"), names);
     }
+
+    private static File newFolder(File root, String... subDirs) throws IOException {
+        String subFolder = String.join("/", subDirs);
+        File result = new File(root, subFolder);
+        if (!result.mkdirs()) {
+            throw new IOException("Couldn't create folders " + root);
+        }
+        return result;
+    }
 }

core/src/test/java/hudson/util/jna/GNUCLibraryTest.java

@@ -1,24 +1,24 @@
 package hudson.util.jna;
 
-import static org.junit.Assert.assertEquals;
-import static org.junit.Assert.assertFalse;
-import static org.junit.Assert.assertNotEquals;
-import static org.junit.Assert.assertTrue;
-import static org.junit.Assume.assumeTrue;
+import static org.junit.jupiter.api.Assertions.assertEquals;
+import static org.junit.jupiter.api.Assertions.assertFalse;
+import static org.junit.jupiter.api.Assertions.assertNotEquals;
+import static org.junit.jupiter.api.Assertions.assertTrue;
+import static org.junit.jupiter.api.Assumptions.assumeTrue;
 
 import hudson.Functions;
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
-import org.junit.Test;
+import org.junit.jupiter.api.Test;
 
-public class GNUCLibraryTest {
+class GNUCLibraryTest {
 
     private static final int O_CREAT = "Linux".equals(System.getProperty("os.name")) ? 64 : 512;
     private static final int O_RDWR = 2;
 
     @Test
-    public void openTest() throws IOException {
+    void openTest() throws IOException {
         assumeTrue(Functions.isGlibcSupported());
 
         int fd = GNUCLibrary.LIBC.open("/dev/null", 0);
@@ -42,7 +42,7 @@ public class GNUCLibraryTest {
     }
 
     @Test
-    public void closeTest() {
+    void closeTest() {
         assumeTrue(Functions.isGlibcSupported());
 
         int fd = GNUCLibrary.LIBC.open("/dev/null", 0);
@@ -53,7 +53,7 @@ public class GNUCLibraryTest {
     }
 
     @Test
-    public void fcntlTest() {
+    void fcntlTest() {
         assumeTrue(Functions.isGlibcSupported());
 
         int fd = GNUCLibrary.LIBC.open("/dev/null", 0);
@@ -72,7 +72,7 @@ public class GNUCLibraryTest {
     }
 
     @Test
-    public void renameTest() throws IOException {
+    void renameTest() throws IOException {
         assumeTrue(Functions.isGlibcSupported());
 
         Path oldFile = Files.createTempFile("renameTest", null);