Fix support for JVM shutdown hooks

junit-platform-console/src/main/java/org/junit/platform/console/ConsoleLauncher.java

@@ -19,6 +19,7 @@
 import org.junit.platform.console.options.CommandFacade;
 import org.junit.platform.console.options.CommandResult;
 import org.junit.platform.console.tasks.ConsoleTestExecutor;
+import org.junit.platform.console.tasks.CustomClassLoaderCloseStrategy;
 
 /**
  * The {@code ConsoleLauncher} is a stand-alone application for launching the
@@ -30,17 +31,20 @@
 public class ConsoleLauncher {
 
 	public static void main(String... args) {
-		CommandResult<?> result = newCommandFacade().run(args);
+		CommandFacade facade = newCommandFacade(CustomClassLoaderCloseStrategy.KEEP_OPEN);
+		CommandResult<?> result = facade.run(args);
 		System.exit(result.getExitCode());
 	}
 
 	@API(status = INTERNAL, since = "1.0")
 	public static CommandResult<?> run(PrintWriter out, PrintWriter err, String... args) {
-		return newCommandFacade().run(args, out, err);
+		CommandFacade facade = newCommandFacade(CustomClassLoaderCloseStrategy.CLOSE_AFTER_CALLING_LAUNCHER);
+		return facade.run(args, out, err);
 	}
 
-	private static CommandFacade newCommandFacade() {
-		return new CommandFacade(ConsoleTestExecutor::new);
+	private static CommandFacade newCommandFacade(CustomClassLoaderCloseStrategy classLoaderCleanupStrategy) {
+		return new CommandFacade((discoveryOptions, outputOptions) -> new ConsoleTestExecutor(discoveryOptions,
+			outputOptions, classLoaderCleanupStrategy));
 	}
 
 }

junit-platform-console/src/main/java/org/junit/platform/console/tasks/ConsoleTestExecutor.java

@@ -50,31 +50,48 @@ public class ConsoleTestExecutor {
 	private final TestDiscoveryOptions discoveryOptions;
 	private final TestConsoleOutputOptions outputOptions;
 	private final Supplier<Launcher> launcherSupplier;
+	private final CustomClassLoaderCloseStrategy classLoaderCloseStrategy;
 
 	public ConsoleTestExecutor(TestDiscoveryOptions discoveryOptions, TestConsoleOutputOptions outputOptions) {
-		this(discoveryOptions, outputOptions, LauncherFactory::create);
+		this(discoveryOptions, outputOptions, CustomClassLoaderCloseStrategy.CLOSE_AFTER_CALLING_LAUNCHER);
+	}
+
+	public ConsoleTestExecutor(TestDiscoveryOptions discoveryOptions, TestConsoleOutputOptions outputOptions,
+			CustomClassLoaderCloseStrategy classLoaderCloseStrategy) {
+		this(discoveryOptions, outputOptions, classLoaderCloseStrategy, LauncherFactory::create);
 	}
 
 	// for tests only
 	ConsoleTestExecutor(TestDiscoveryOptions discoveryOptions, TestConsoleOutputOptions outputOptions,
 			Supplier<Launcher> launcherSupplier) {
+		this(discoveryOptions, outputOptions, CustomClassLoaderCloseStrategy.CLOSE_AFTER_CALLING_LAUNCHER,
+			launcherSupplier);
+	}
+
+	private ConsoleTestExecutor(TestDiscoveryOptions discoveryOptions, TestConsoleOutputOptions outputOptions,
+			CustomClassLoaderCloseStrategy classLoaderCloseStrategy, Supplier<Launcher> launcherSupplier) {
 		this.discoveryOptions = discoveryOptions;
 		this.outputOptions = outputOptions;
 		this.launcherSupplier = launcherSupplier;
+		this.classLoaderCloseStrategy = classLoaderCloseStrategy;
 	}
 
 	public void discover(PrintWriter out) {
-		new CustomContextClassLoaderExecutor(createCustomClassLoader()).invoke(() -> {
+		createCustomContextClassLoaderExecutor().invoke(() -> {
 			discoverTests(out);
 			return null;
 		});
 	}
 
 	public TestExecutionSummary execute(PrintWriter out, Optional<Path> reportsDir) {
-		return new CustomContextClassLoaderExecutor(createCustomClassLoader()) //
+		return createCustomContextClassLoaderExecutor() //
 				.invoke(() -> executeTests(out, reportsDir));
 	}
 
+	private CustomContextClassLoaderExecutor createCustomContextClassLoaderExecutor() {
+		return new CustomContextClassLoaderExecutor(createCustomClassLoader(), classLoaderCloseStrategy);
+	}
+
 	private void discoverTests(PrintWriter out) {
 		Launcher launcher = launcherSupplier.get();
 		Optional<DetailsPrintingListener> commandLineTestPrinter = createDetailsPrintingListener(out);

junit-platform-console/src/main/java/org/junit/platform/console/tasks/CustomClassLoaderCloseStrategy.java

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2015-2025 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package org.junit.platform.console.tasks;
+
+import static org.apiguardian.api.API.Status.INTERNAL;
+
+import org.apiguardian.api.API;
+import org.junit.platform.commons.JUnitException;
+
+/**
+ * Defines the strategy for closing custom class loaders created for test
+ * discovery and execution.
+ */
+@API(status = INTERNAL, since = "1.13")
+public enum CustomClassLoaderCloseStrategy {
+
+	/**
+	 * Close the custom class loader after calling the
+	 * {@link org.junit.platform.launcher.Launcher} for test discovery or
+	 * execution.
+	 */
+	CLOSE_AFTER_CALLING_LAUNCHER {
+
+		@Override
+		public void handle(ClassLoader customClassLoader) {
+			if (customClassLoader instanceof AutoCloseable) {
+				close((AutoCloseable) customClassLoader);
+			}
+		}
+
+		private void close(AutoCloseable customClassLoader) {
+			try {
+				customClassLoader.close();
+			}
+			catch (Exception e) {
+				throw new JUnitException("Failed to close custom class loader", e);
+			}
+		}
+	},
+
+	/**
+	 * Rely on the JVM to release resources held by the custom class loader when
+	 * it terminates.
+	 *
+	 * <p>This mode is only safe to use when calling {@link System#exit(int)}
+	 * afterward.
+	 */
+	KEEP_OPEN {
+		@Override
+		public void handle(ClassLoader customClassLoader) {
+			// do nothing
+		}
+	};
+
+	/**
+	 * Handle the class loader according to the strategy.
+	 */
+	public abstract void handle(ClassLoader classLoader);
+
+}

junit-platform-console/src/main/java/org/junit/platform/console/tasks/CustomContextClassLoaderExecutor.java

@@ -13,17 +13,22 @@
 import java.util.Optional;
 import java.util.function.Supplier;
 
-import org.junit.platform.commons.JUnitException;
-
 /**
  * @since 1.0
  */
 class CustomContextClassLoaderExecutor {
 
 	private final Optional<ClassLoader> customClassLoader;
+	private final CustomClassLoaderCloseStrategy closeStrategy;
 
 	CustomContextClassLoaderExecutor(Optional<ClassLoader> customClassLoader) {
+		this(customClassLoader, CustomClassLoaderCloseStrategy.CLOSE_AFTER_CALLING_LAUNCHER);
+	}
+
+	CustomContextClassLoaderExecutor(Optional<ClassLoader> customClassLoader,
+			CustomClassLoaderCloseStrategy closeStrategy) {
 		this.customClassLoader = customClassLoader;
+		this.closeStrategy = closeStrategy;
 	}
 
 	<T> T invoke(Supplier<T> supplier) {
@@ -43,18 +48,7 @@ private <T> T replaceThreadContextClassLoaderAndInvoke(ClassLoader customClassLo
 		}
 		finally {
 			Thread.currentThread().setContextClassLoader(originalClassLoader);
-			if (customClassLoader instanceof AutoCloseable) {
-				close((AutoCloseable) customClassLoader);
-			}
-		}
-	}
-
-	private static void close(AutoCloseable customClassLoader) {
-		try {
-			customClassLoader.close();
-		}
-		catch (Exception e) {
-			throw new JUnitException("Failed to close custom class loader", e);
+			closeStrategy.handle(customClassLoader);
 		}
 	}
 

platform-tests/src/test/java/org/junit/platform/console/tasks/CustomContextClassLoaderExecutorTests.java

@@ -11,6 +11,7 @@
 package org.junit.platform.console.tasks;
 
 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.assertTrue;
 
@@ -28,7 +29,7 @@
 class CustomContextClassLoaderExecutorTests {
 
 	@Test
-	void invokeWithoutCustomClassLoaderDoesNotSetClassLoader() throws Exception {
+	void invokeWithoutCustomClassLoaderDoesNotSetClassLoader() {
 		var originalClassLoader = Thread.currentThread().getContextClassLoader();
 		var executor = new CustomContextClassLoaderExecutor(Optional.empty());
 
@@ -42,7 +43,7 @@ void invokeWithoutCustomClassLoaderDoesNotSetClassLoader() throws Exception {
 	}
 
 	@Test
-	void invokeWithCustomClassLoaderSetsCustomAndResetsToOriginal() throws Exception {
+	void invokeWithCustomClassLoaderSetsCustomAndResetsToOriginal() {
 		var originalClassLoader = Thread.currentThread().getContextClassLoader();
 		ClassLoader customClassLoader = URLClassLoader.newInstance(new URL[0]);
 		var executor = new CustomContextClassLoaderExecutor(Optional.of(customClassLoader));
@@ -57,7 +58,7 @@ void invokeWithCustomClassLoaderSetsCustomAndResetsToOriginal() throws Exception
 	}
 
 	@Test
-	void invokeWithCustomClassLoaderAndEnsureItIsClosedAfterUsage() throws Exception {
+	void invokeWithCustomClassLoaderAndEnsureItIsClosedAfterUsage() {
 		var closed = new AtomicBoolean(false);
 		ClassLoader localClassLoader = new URLClassLoader(new URL[0]) {
 			@Override
@@ -73,4 +74,23 @@ public void close() throws IOException {
 		assertEquals(4711, result);
 		assertTrue(closed.get());
 	}
+
+	@Test
+	void invokeWithCustomClassLoaderAndKeepItOpenAfterUsage() {
+		var closed = new AtomicBoolean(false);
+		ClassLoader localClassLoader = new URLClassLoader(new URL[0]) {
+			@Override
+			public void close() throws IOException {
+				closed.set(true);
+				super.close();
+			}
+		};
+		var executor = new CustomContextClassLoaderExecutor(Optional.of(localClassLoader),
+			CustomClassLoaderCloseStrategy.KEEP_OPEN);
+
+		int result = executor.invoke(() -> 4711);
+
+		assertEquals(4711, result);
+		assertFalse(closed.get());
+	}
 }

platform-tooling-support-tests/projects/standalone/src/other/OtherwiseNotReferencedClass.java

@@ -0,0 +1,14 @@
+/*
+ * Copyright 2015-2025 the original author or authors.
+ *
+ * All rights reserved. This program and the accompanying materials are
+ * made available under the terms of the Eclipse Public License v2.0 which
+ * accompanies this distribution and is available at
+ *
+ * https://www.eclipse.org/legal/epl-v20.html
+ */
+
+package other;
+
+public class OtherwiseNotReferencedClass {
+}

platform-tooling-support-tests/projects/standalone/src/standalone/JupiterIntegration.java

@@ -19,6 +19,9 @@ class JupiterIntegration {
 
 	@Test
 	void successful() {
+		Runtime.getRuntime().addShutdownHook(new Thread(() -> {
+			new other.OtherwiseNotReferencedClass();
+		}));
 	}
 
 	@Test