Configure JUL/log4j for JUnit 5 in spring-test

Issue: SPR-14431

build.gradle

@@ -890,6 +890,8 @@ project("spring-test") {
 		testCompile("org.apache.httpcomponents:httpclient:${httpclientVersion}")
 		testCompile("javax.cache:cache-api:1.0.0")
 		testRuntime("org.junit.jupiter:junit-jupiter-engine:${junitJupiterVersion}")
+		// Java Util Logging for JUnit 5.
+		testRuntime("org.apache.logging.log4j:log4j-jul:${log4jVersion}")
 		testRuntime("org.ehcache:ehcache:${ehcache3Version}")
 		testRuntime("org.terracotta:management-model:2.0.0")
 	}
@@ -911,6 +913,8 @@ project("spring-test") {
 		scanForTestClasses = false
 		include(['**/*Tests.class', '**/*Test.class', '**/SpringJUnitJupiterTestSuite.class'])
 		exclude(['**/testng/**/*.*'])
+		// Java Util Logging for JUnit 5.
+		// systemProperty('java.util.logging.manager', 'org.apache.logging.log4j.jul.LogManager')
 	}
 
 	task aggregateTestReports(type: TestReport) {

spring-test/src/test/java/org/springframework/test/context/junit/SpringJUnitJupiterTestSuite.java

@@ -31,6 +31,16 @@ import org.junit.runner.RunWith;
  * build. This class is therefore responsible for executing all JUnit
  * Jupiter based tests in Spring's official test suite.
  *
+ * <h3>Logging Configuration</h3>
+ *
+ * <p>In order for our log4j2 configuration to be used in an IDE, you must
+ * set the following system property before running any tests &mdash; for
+ * example, in <em>Run Configurations</em> in Eclipse.
+ *
+ * <pre style="code">
+ * -Djava.util.logging.manager=org.apache.logging.log4j.jul.LogManager
+ * </pre>
+ *
  * @author Sam Brannen
  * @since 5.0
  */

spring-test/src/test/resources/log4j2-test.xml

@@ -9,6 +9,7 @@
 		</File>
 	</Appenders>
 	<Loggers>
+		<Logger name="org.junit.platform" level="info" />
 		<Logger name="org.springframework.test.context" level="warn" />
 		<Logger name="org.springframework.test.context.TestContext" level="warn" />
 		<Logger name="org.springframework.test.context.TestContextManager" level="warn" />