KAFKA-18128 Fix failed test MetadataSchemaCheckerToolTest.testVerifyEvolutionGit in PR (#17996)

Reviewers: Chia-Ping Tsai <chia7712@gmail.com>

generator/src/main/java/org/apache/kafka/message/checker/CheckerUtils.java

@@ -35,6 +35,7 @@ import org.eclipse.jgit.treewalk.filter.PathFilter;
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.charset.StandardCharsets;
 import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
@@ -122,13 +123,18 @@ class CheckerUtils {
     /**
      * Read a MessageSpec file from remote git repo.
      *
-     * @param filePath   The file to read from remote git repo.
+     * @param filePath The file to read from remote git repo.
-     * @return                     The file contents.
+     * @param ref The specific git reference to be used for testing.
+     * @return The file contents.
      */
-    static String GetDataFromGit(String filePath, Path gitPath) throws IOException {
+    static String getDataFromGit(String filePath, Path gitPath, String ref) throws IOException {
         Git git = Git.open(new File(gitPath + "/.git"));
         Repository repository = git.getRepository();
-        Ref head = git.getRepository().getRefDatabase().firstExactRef("refs/heads/trunk");
+        Ref head = repository.getRefDatabase().findRef(ref);
+        if (head == null) {
+            throw new IllegalStateException("Cannot find " + ref + " in the repository.");
+        }
+
         try (RevWalk revWalk = new RevWalk(repository)) {
             RevCommit commit = revWalk.parseCommit(head.getObjectId());
             RevTree tree = commit.getTree();
@@ -141,7 +147,7 @@ class CheckerUtils {
                 }
                 ObjectId objectId = treeWalk.getObjectId(0);
                 ObjectLoader loader = repository.open(objectId);
-                return new String(loader.getBytes(), "UTF-8");
+                return new String(loader.getBytes(), StandardCharsets.UTF_8);
             }
         }
     }

generator/src/main/java/org/apache/kafka/message/checker/MetadataSchemaCheckerTool.java

@@ -25,10 +25,11 @@ import net.sourceforge.argparse4j.inf.Subparsers;
 import net.sourceforge.argparse4j.internal.HelpScreenException;
 
 import java.io.PrintStream;
+import java.nio.file.Files;
 import java.nio.file.Path;
 import java.nio.file.Paths;
 
-import static org.apache.kafka.message.checker.CheckerUtils.GetDataFromGit;
+import static org.apache.kafka.message.checker.CheckerUtils.getDataFromGit;
 
 public class MetadataSchemaCheckerTool {
     public static void main(String[] args) throws Exception {
@@ -65,6 +66,10 @@ public class MetadataSchemaCheckerTool {
         evolutionGitVerifierParser.addArgument("--file", "-3").
             required(true).
             help("The edited JSON file");
+        evolutionGitVerifierParser.addArgument("--ref", "-4")
+            .required(false)
+            .setDefault("refs/heads/trunk")
+            .help("Optional Git reference to be used for testing. Defaults to 'refs/heads/trunk' if not specified.");
         Namespace namespace;
         if (args.length == 0) {
             namespace = argumentParser.parseArgs(new String[] {"--help"});
@@ -93,13 +98,13 @@ public class MetadataSchemaCheckerTool {
             case "verify-evolution-git": {
                 String filePath = "/metadata/src/main/resources/common/metadata/" + namespace.getString("file");
                 Path rootKafkaDirectory = Paths.get("").toAbsolutePath();
-                while (!rootKafkaDirectory.endsWith("kafka")) {
+                while (!Files.exists(rootKafkaDirectory.resolve(".git"))) {
                     rootKafkaDirectory = rootKafkaDirectory.getParent();
                     if (rootKafkaDirectory == null) {
-                        throw new RuntimeException("Invalid directory, need to be within the kafka directory");
+                        throw new RuntimeException("Invalid directory, need to be within a Git repository");
                     }
                 }
-                String gitContent = GetDataFromGit(filePath, rootKafkaDirectory);
+                String gitContent = getDataFromGit(filePath, rootKafkaDirectory, namespace.getString("ref"));
                 EvolutionVerifier verifier = new EvolutionVerifier(
                         CheckerUtils.readMessageSpecFromFile(rootKafkaDirectory + filePath),
                         CheckerUtils.readMessageSpecFromString(gitContent));

generator/src/test/java/org/apache/kafka/message/checker/MetadataSchemaCheckerToolTest.java

@@ -29,7 +29,12 @@ public class MetadataSchemaCheckerToolTest {
     @Test
     public void testVerifyEvolutionGit() throws Exception {
         try (ByteArrayOutputStream stream = new ByteArrayOutputStream()) {
-            MetadataSchemaCheckerTool.run(new String[]{"verify-evolution-git", "--file", "AbortTransactionRecord.json"}, new PrintStream(stream));
+            MetadataSchemaCheckerTool.run(
+                // In the CI environment because the CI fetch command only creates HEAD and refs/remotes/pull/... references.
+                // Since there may not be other branches like refs/heads/trunk in CI, HEAD serves as the baseline reference.
+                new String[]{"verify-evolution-git", "--file", "AbortTransactionRecord.json", "--ref", "HEAD"},
+                new PrintStream(stream)
+            );
             assertEquals("Successfully verified evolution of file: AbortTransactionRecord.json",
                 stream.toString().trim());
         }