Register EventPublishingTestExecutionListener by default (round 2)

This commit registers the EventPublishingTestExecutionListener as a
default TestExecutionListener with an order of 10,000. This registers
the EventPublishingTestExecutionListener as the last listener provided
by the Spring Framework.

With EventPublishingTestExecutionListener registered with an order of
10,000, it is effectively wrapped by all other Spring listeners,
including support for @DirtiesContext and test-managed transactions.

Furthermore, this commit revises the implementation of
EventPublishingTestExecutionListener to take advantage of the new
TestContext#hasApplicationContext() support which allows the
EventPublishingTestExecutionListener to publish events only if the
test's ApplicationContext is currently available. This avoids
undesirable side-effects such as eager loading of the
ApplicationContext before it is needed or re-loading of the
ApplicationContext after it has been intentionally closed.

Closes gh-18490

spring-test/src/main/java/org/springframework/test/context/TestExecutionListener.java

@@ -44,8 +44,6 @@ package org.springframework.test.context;
  * <p>Spring provides the following out-of-the-box implementations (all of
  * which implement {@code Ordered}):
  * <ul>
- * <li>{@link org.springframework.test.context.event.EventPublishingTestExecutionListener
- * EventPublishingTestExecutionListener} (not registered by default)</li>
  * <li>{@link org.springframework.test.context.web.ServletTestExecutionListener
  * ServletTestExecutionListener}</li>
  * <li>{@link org.springframework.test.context.support.DirtiesContextBeforeModesTestExecutionListener
@@ -58,6 +56,8 @@ package org.springframework.test.context;
  * TransactionalTestExecutionListener}</li>
  * <li>{@link org.springframework.test.context.jdbc.SqlScriptsTestExecutionListener
  * SqlScriptsTestExecutionListener}</li>
+ * <li>{@link org.springframework.test.context.event.EventPublishingTestExecutionListener
+ * EventPublishingTestExecutionListener}</li>
  * </ul>
  *
  * @author Sam Brannen

spring-test/src/main/java/org/springframework/test/context/event/EventPublishingTestExecutionListener.java

@@ -16,15 +16,19 @@
 
 package org.springframework.test.context.event;
 
-import org.springframework.core.Ordered;
+import java.util.function.Function;
+
 import org.springframework.test.context.TestContext;
 import org.springframework.test.context.TestExecutionListener;
 import org.springframework.test.context.support.AbstractTestExecutionListener;
 
 /**
  * {@link org.springframework.test.context.TestExecutionListener TestExecutionListener}
- * that publishes test execution events to a Spring test
- * {@link org.springframework.context.ApplicationContext ApplicationContext}.
+ * that publishes test execution events to the
+ * {@link org.springframework.context.ApplicationContext ApplicationContext}
+ * for the currently executing test. Events are only published if the
+ * {@code ApplicationContext} {@linkplain TestContext#hasApplicationContext()
+ * has already been loaded}.
  *
  * <h3>Supported Events</h3>
  * <ul>
@@ -61,16 +65,8 @@ import org.springframework.test.context.support.AbstractTestExecutionListener;
  * support. For further details, consult the class-level Javadoc for
  * {@link org.springframework.context.event.EventListener @EventListener}.
  *
- * <h3>Listener Registration</h3>
- * <p>Note that this {@code TestExecutionListener} is not registered by default,
- * but it may be registered for a given test class via
- * {@link org.springframework.test.context.TestExecutionListeners @TestExecutionListeners}
- * or globally via the {@link org.springframework.core.io.support.SpringFactoriesLoader
- * SpringFactoriesLoader} mechanism (consult the Javadoc and Spring reference manual for
- * details).
- *
- * @author Frank Scheffler
  * @author Sam Brannen
+ * @author Frank Scheffler
  * @since 5.2
  * @see org.springframework.test.context.event.annotation.BeforeTestClass @BeforeTestClass
  * @see org.springframework.test.context.event.annotation.PrepareTestInstance @PrepareTestInstance
@@ -83,74 +79,80 @@ import org.springframework.test.context.support.AbstractTestExecutionListener;
 public class EventPublishingTestExecutionListener extends AbstractTestExecutionListener {
 
 	/**
-	 * Returns {@link Ordered#HIGHEST_PRECEDENCE}.
+	 * Returns {@code 10000}.
 	 */
 	@Override
-	public int getOrder() {
-		return Ordered.HIGHEST_PRECEDENCE;
+	public final int getOrder() {
+		return 10_000;
 	}
 
 	/**
-	 * Publishes a {@link BeforeTestClassEvent} to the {@code ApplicationContext}
+	 * Publish a {@link BeforeTestClassEvent} to the {@code ApplicationContext}
 	 * for the supplied {@link TestContext}.
 	 */
 	@Override
 	public void beforeTestClass(TestContext testContext) {
-		testContext.getApplicationContext().publishEvent(new BeforeTestClassEvent(testContext));
+		publishEvent(testContext, BeforeTestClassEvent::new);
 	}
 
 	/**
-	 * Publishes a {@link PrepareTestInstanceEvent} to the {@code ApplicationContext}
+	 * Publish a {@link PrepareTestInstanceEvent} to the {@code ApplicationContext}
 	 * for the supplied {@link TestContext}.
 	 */
 	@Override
 	public void prepareTestInstance(TestContext testContext) {
-		testContext.getApplicationContext().publishEvent(new PrepareTestInstanceEvent(testContext));
+		publishEvent(testContext, PrepareTestInstanceEvent::new);
 	}
 
 	/**
-	 * Publishes a {@link BeforeTestMethodEvent} to the {@code ApplicationContext}
+	 * Publish a {@link BeforeTestMethodEvent} to the {@code ApplicationContext}
 	 * for the supplied {@link TestContext}.
 	 */
 	@Override
 	public void beforeTestMethod(TestContext testContext) {
-		testContext.getApplicationContext().publishEvent(new BeforeTestMethodEvent(testContext));
+		publishEvent(testContext, BeforeTestMethodEvent::new);
 	}
 
 	/**
-	 * Publishes a {@link BeforeTestExecutionEvent} to the {@code ApplicationContext}
+	 * Publish a {@link BeforeTestExecutionEvent} to the {@code ApplicationContext}
 	 * for the supplied {@link TestContext}.
 	 */
 	@Override
 	public void beforeTestExecution(TestContext testContext) {
-		testContext.getApplicationContext().publishEvent(new BeforeTestExecutionEvent(testContext));
+		publishEvent(testContext, BeforeTestExecutionEvent::new);
 	}
 
 	/**
-	 * Publishes an {@link AfterTestExecutionEvent} to the {@code ApplicationContext}
+	 * Publish an {@link AfterTestExecutionEvent} to the {@code ApplicationContext}
 	 * for the supplied {@link TestContext}.
 	 */
 	@Override
 	public void afterTestExecution(TestContext testContext) {
-		testContext.getApplicationContext().publishEvent(new AfterTestExecutionEvent(testContext));
+		publishEvent(testContext, AfterTestExecutionEvent::new);
 	}
 
 	/**
-	 * Publishes an {@link AfterTestMethodEvent} to the {@code ApplicationContext}
+	 * Publish an {@link AfterTestMethodEvent} to the {@code ApplicationContext}
 	 * for the supplied {@link TestContext}.
 	 */
 	@Override
 	public void afterTestMethod(TestContext testContext) {
-		testContext.getApplicationContext().publishEvent(new AfterTestMethodEvent(testContext));
+		publishEvent(testContext, AfterTestMethodEvent::new);
 	}
 
 	/**
-	 * Publishes an {@link AfterTestClassEvent} to the {@code ApplicationContext}
+	 * Publish an {@link AfterTestClassEvent} to the {@code ApplicationContext}
 	 * for the supplied {@link TestContext}.
 	 */
 	@Override
 	public void afterTestClass(TestContext testContext) {
-		testContext.getApplicationContext().publishEvent(new AfterTestClassEvent(testContext));
+		publishEvent(testContext, AfterTestClassEvent::new);
+	}
+
+	private void publishEvent(TestContext testContext, Function<TestContext, TestContextEvent> eventFactory) {
+		if (testContext.hasApplicationContext()) {
+			testContext.getApplicationContext().publishEvent(eventFactory.apply(testContext));
+		}
 	}
 
 }