Introduce @AutoClose

documentation/src/docs/asciidoc/link-attributes.adoc

@@ -153,6 +153,7 @@ endif::[]
 // Jupiter Engine
 :junit-jupiter-engine:                       {javadoc-root}/org.junit.jupiter.engine/org/junit/jupiter/engine/package-summary.html[junit-jupiter-engine]
 // Jupiter Extension Implementations
+:AutoCloseExtension:                         {current-branch}/junit-jupiter-api/src/main/java/org/junit/jupiter/api/AutoCloseExtension.java[AutoCloseExtension]
 :DisabledCondition:                          {current-branch}/junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/extension/DisabledCondition.java[DisabledCondition]
 :RepetitionExtension:                        {current-branch}/junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/extension/RepetitionExtension.java[RepetitionExtension]
 :TempDirectory:                              {current-branch}/junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/extension/TempDirectory.java[TempDirectory]

documentation/src/docs/asciidoc/release-notes/release-notes-5.11.0-M1.adoc

@@ -45,7 +45,10 @@ repository on GitHub.
 
 ==== New Features and Improvements
 
-* ❓
+* The new `@AutoClose` annotation can be applied to fields within tests to automatically
+  close the annotated resource after test execution. See
+  <<../user-guide/index.adoc#writing-tests-built-in-extensions-AutoClose, User Guide>> for
+  details.
 
 
 [[release-notes-5.11.0-M1-junit-vintage]]

documentation/src/docs/asciidoc/user-guide/writing-tests.adoc

@@ -45,6 +45,7 @@ in the `junit-jupiter-api` module.
 | `@ExtendWith`            | Used to <<extensions-registration-declarative,register extensions declaratively>>. Such annotations are _inherited_.
 | `@RegisterExtension`     | Used to <<extensions-registration-programmatic,register extensions programmatically>> via fields. Such fields are _inherited_ unless they are _shadowed_.
 | `@TempDir`               | Used to supply a <<writing-tests-built-in-extensions-TempDirectory,temporary directory>> via field injection or parameter injection in a lifecycle method or test method; located in the `org.junit.jupiter.api.io` package.
+| `@AutoClose`             | Denotes that the annotated field represents a resource that should be automatically closed after test execution.
 |===
 
 WARNING: Some annotations may currently be _experimental_. Consult the table in
@@ -2709,3 +2710,26 @@ following precedence rules:
 2. The default `TempDirFactory` configured via the configuration
 parameter, if present
 3. Otherwise, `org.junit.jupiter.api.io.TempDirFactory$Standard` will be used.
+
+[[writing-tests-built-in-extensions-AutoClose]]
+==== The AutoClose Extension
+
+The built-in `{AutoCloseExtension}` is used to automatically close resources used in
+tests. Therefore, the `@AutoClose` annotation is applied to fields within the
+test class to indicate that the annotated resource should be automatically closed after
+the test execution.
+
+By default, the `@AutoClose` annotation expects the annotated resource to provide
+a `close()` method that will be invoked for closing the resource. However, developers
+can customize the closing behavior by providing a different method name through the
+`value` attribute. For example, setting `value = "shutdown"` will look
+for a method named `shutdown()` to close the resource.
+
+For example, the following test declares a database connection field annotated with
+`@AutoClose` that is automatically closed afterward.
+
+[source,java,indent=0]
+.A test class using @AutoClose annotation to close used resource
+----
+include::{testDir}/example/AutoCloseDemo.java[tags=user_guide_example]
+----

documentation/src/test/java/example/AutoCloseDemo.java

@@ -0,0 +1,49 @@
+/*
+ * Copyright 2015-2023 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 example;
+
+import static org.junit.jupiter.api.Assertions.assertTrue;
+
+import java.sql.Connection;
+import java.sql.DriverManager;
+import java.sql.ResultSet;
+import java.sql.SQLException;
+
+import org.junit.jupiter.api.AutoClose;
+import org.junit.jupiter.api.Disabled;
+import org.junit.jupiter.api.Test;
+
+@Disabled
+// tag::user_guide_example[]
+class AutoCloseDemo {
+
+	@AutoClose
+	Connection connection = getJdbcConnection("jdbc:mysql://localhost/testdb");
+
+	@Test
+	void usersTableHasEntries() throws SQLException {
+		ResultSet resultSet = connection.createStatement().executeQuery("SELECT * FROM users");
+
+		assertTrue(resultSet.next());
+	}
+
+	// ...
+	// end::user_guide_example[]
+	private static Connection getJdbcConnection(String url) {
+		try {
+			return DriverManager.getConnection(url);
+		}
+		catch (SQLException ex) {
+			throw new RuntimeException(ex);
+		}
+	}
+
+}

junit-jupiter-api/src/main/java/org/junit/jupiter/api/AutoClose.java

@@ -0,0 +1,59 @@
+/*
+ * Copyright 2015-2023 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.jupiter.api;
+
+import java.lang.annotation.Documented;
+import java.lang.annotation.ElementType;
+import java.lang.annotation.Retention;
+import java.lang.annotation.RetentionPolicy;
+import java.lang.annotation.Target;
+
+import org.apiguardian.api.API;
+import org.junit.jupiter.api.extension.ExtendWith;
+
+/**
+ * The {@code AutoClose} annotation is used to automatically close resources
+ * used in tests.
+ *
+ * <p>This annotation should be applied to fields within test classes. It
+ * indicates that the annotated resource should be automatically closed after
+ * the test execution.
+ *
+ * <p>By default, the {@code AutoClose} annotation expects the annotated
+ * resource to provide a {@code close()} method that will be invoked for closing
+ * the resource. However, developers can customize the closing behavior by
+ * providing a different method name through the {@link #value} attribute. For
+ * example, setting {@code value = "shutdown"} will look for a method named
+ * {@code shutdown()} to close the resource. When multiple annotated resources
+ * exist the order of closing them is unspecified.
+ *
+ * @since 5.11
+ * @see java.lang.annotation.Retention
+ * @see java.lang.annotation.Target
+ */
+@Target(ElementType.FIELD)
+@Retention(RetentionPolicy.RUNTIME)
+@Documented
+@ExtendWith(AutoCloseExtension.class)
+@API(status = API.Status.EXPERIMENTAL, since = "5.11")
+@SuppressWarnings("exports")
+public @interface AutoClose {
+
+	/**
+	 * Specifies the name of the method to invoke for closing the resource.
+	 *
+	 * <p>The default value is {@code close}.
+	 *
+	 * @return the method name for closing the resource
+	 */
+	String value() default "close";
+
+}

junit-jupiter-api/src/main/java/org/junit/jupiter/api/AutoCloseExtension.java

@@ -0,0 +1,99 @@
+/*
+ * Copyright 2015-2023 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.jupiter.api;
+
+import static org.junit.platform.commons.util.AnnotationUtils.findAnnotatedFields;
+
+import java.lang.reflect.Field;
+import java.lang.reflect.Method;
+import java.util.function.Predicate;
+
+import org.junit.jupiter.api.extension.AfterAllCallback;
+import org.junit.jupiter.api.extension.ExtensionConfigurationException;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.junit.jupiter.api.extension.ExtensionContext.Namespace;
+import org.junit.jupiter.api.extension.ExtensionContext.Store;
+import org.junit.jupiter.api.extension.TestInstancePreDestroyCallback;
+import org.junit.platform.commons.logging.Logger;
+import org.junit.platform.commons.logging.LoggerFactory;
+import org.junit.platform.commons.util.ExceptionUtils;
+import org.junit.platform.commons.util.ReflectionUtils;
+
+/**
+ * {@code AutoCloseExtension} is a JUnit Jupiter extension that closes resources
+ * if a field in a test class is annotated with {@link AutoClose @AutoClose}.
+ *
+ * <p>Consult the Javadoc for {@link AutoClose @AutoClose} for details on the
+ * contract.
+ *
+ * @since 5.11
+ * @see AutoClose
+ */
+class AutoCloseExtension implements AfterAllCallback, TestInstancePreDestroyCallback {
+
+	private static final Logger logger = LoggerFactory.getLogger(AutoCloseExtension.class);
+	private static final Namespace NAMESPACE = Namespace.create(AutoClose.class);
+
+	@Override
+	public void afterAll(ExtensionContext context) {
+		Store contextStore = context.getStore(NAMESPACE);
+		Class<?> testClass = context.getRequiredTestClass();
+
+		registerCloseables(contextStore, testClass, null);
+	}
+
+	@Override
+	public void preDestroyTestInstance(ExtensionContext context) {
+		Store contextStore = context.getStore(NAMESPACE);
+
+		for (Object instance : context.getRequiredTestInstances().getAllInstances()) {
+			registerCloseables(contextStore, instance.getClass(), instance);
+		}
+	}
+
+	private void registerCloseables(Store contextStore, Class<?> testClass, Object testInstance) {
+		Predicate<Field> predicate = testInstance == null ? ReflectionUtils::isStatic : ReflectionUtils::isNotStatic;
+		findAnnotatedFields(testClass, AutoClose.class, predicate).forEach(field -> {
+			try {
+				contextStore.put(field, asCloseableResource(testInstance, field));
+			}
+			catch (Throwable t) {
+				throw ExceptionUtils.throwAsUncheckedException(t);
+			}
+		});
+	}
+
+	private static Store.CloseableResource asCloseableResource(Object testInstance, Field field) {
+		return () -> {
+			Object toBeClosed = ReflectionUtils.tryToReadFieldValue(field, testInstance).get();
+			if (toBeClosed == null) {
+				logger.warn(() -> "@AutoClose couldn't close object for field " + getQualifiedFieldName(field)
+						+ "  because it was null.");
+				return;
+			}
+			invokeCloseMethod(field, toBeClosed);
+		};
+	}
+
+	private static void invokeCloseMethod(Field field, Object toBeClosed) {
+		String methodName = field.getAnnotation(AutoClose.class).value();
+		Method closeMethod = ReflectionUtils.findMethod(toBeClosed.getClass(), methodName).orElseThrow(
+			() -> new ExtensionConfigurationException(
+				"@AutoClose failed to close object for field " + getQualifiedFieldName(field) + " because the "
+						+ methodName + "() method could not be " + "resolved."));
+		ReflectionUtils.invokeMethod(closeMethod, toBeClosed);
+	}
+
+	private static String getQualifiedFieldName(Field field) {
+		return field.getDeclaringClass().getName() + "." + field.getName();
+	}
+
+}

junit-jupiter-api/src/module/org.junit.jupiter.api/module-info.java

@@ -23,5 +23,6 @@
 	exports org.junit.jupiter.api.io;
 	exports org.junit.jupiter.api.parallel;
 
+	opens org.junit.jupiter.api to org.junit.platform.commons;
 	opens org.junit.jupiter.api.condition to org.junit.platform.commons;
 }