Consistently use class literals for primitive types

To improve consistency and avoid confusion regarding primitive types
and their wrapper types, this commit ensures that we always use class
literals for primitive types.

For example, instead of using the `Void.TYPE` constant, we now
consistently use `void.class`.

Author: sbrannen

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/descriptor/LifecycleMethodUtils.java

@@ -11,7 +11,7 @@
 package org.junit.jupiter.engine.descriptor;
 
 import static org.junit.platform.commons.util.AnnotationUtils.findAnnotatedMethods;
-import static org.junit.platform.commons.util.ReflectionUtils.returnsVoid;
+import static org.junit.platform.commons.util.ReflectionUtils.returnsPrimitiveVoid;
 
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
@@ -96,7 +96,7 @@ private static void assertNonStatic(Class<? extends Annotation> annotationType,
 	}
 
 	private static void assertVoid(Class<? extends Annotation> annotationType, Method method) {
-		if (!returnsVoid(method)) {
+		if (!returnsPrimitiveVoid(method)) {
 			throw new JUnitException(String.format("@%s method '%s' must not return a value.",
 				annotationType.getSimpleName(), method.toGenericString()));
 		}

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/discovery/predicates/IsTestableMethod.java

@@ -14,7 +14,7 @@
 import static org.junit.platform.commons.util.ReflectionUtils.isAbstract;
 import static org.junit.platform.commons.util.ReflectionUtils.isPrivate;
 import static org.junit.platform.commons.util.ReflectionUtils.isStatic;
-import static org.junit.platform.commons.util.ReflectionUtils.returnsVoid;
+import static org.junit.platform.commons.util.ReflectionUtils.returnsPrimitiveVoid;
 
 import java.lang.annotation.Annotation;
 import java.lang.reflect.Method;
@@ -26,11 +26,11 @@
 abstract class IsTestableMethod implements Predicate<Method> {
 
 	private final Class<? extends Annotation> annotationType;
-	private final boolean mustReturnVoid;
+	private final boolean mustReturnPrimitiveVoid;
 
-	IsTestableMethod(Class<? extends Annotation> annotationType, boolean mustReturnVoid) {
+	IsTestableMethod(Class<? extends Annotation> annotationType, boolean mustReturnPrimitiveVoid) {
 		this.annotationType = annotationType;
-		this.mustReturnVoid = mustReturnVoid;
+		this.mustReturnPrimitiveVoid = mustReturnPrimitiveVoid;
 	}
 
 	@Override
@@ -45,7 +45,7 @@ public boolean test(Method candidate) {
 		if (isAbstract(candidate)) {
 			return false;
 		}
-		if (returnsVoid(candidate) != this.mustReturnVoid) {
+		if (returnsPrimitiveVoid(candidate) != this.mustReturnPrimitiveVoid) {
 			return false;
 		}
 

junit-platform-commons/src/main/java/org/junit/platform/commons/util/ReflectionUtils.java

@@ -341,8 +341,14 @@ public static boolean isInnerClass(Class<?> clazz) {
 		return !isStatic(clazz) && clazz.isMemberClass();
 	}
 
-	public static boolean returnsVoid(Method method) {
-		return method.getReturnType().equals(Void.TYPE);
+	/**
+	 * Determine if the return type of the supplied method is primitive {@code void}.
+	 *
+	 * @param method the method to test; never {@code null}
+	 * @return {@code true} if the method's return type is {@code void}
+	 */
+	public static boolean returnsPrimitiveVoid(Method method) {
+		return method.getReturnType() == void.class;
 	}
 
 	/**

junit-platform-engine/src/main/java/org/junit/platform/engine/support/hierarchical/ForkJoinPoolHierarchicalTestExecutorService.java

@@ -94,9 +94,9 @@ private ForkJoinPool createForkJoinPool(ParallelExecutionConfiguration configura
 	}
 
 	private static Optional<Constructor<ForkJoinPool>> sinceJava9Constructor() {
-		return Try.call(() -> ForkJoinPool.class.getDeclaredConstructor(Integer.TYPE, ForkJoinWorkerThreadFactory.class,
-			UncaughtExceptionHandler.class, Boolean.TYPE, Integer.TYPE, Integer.TYPE, Integer.TYPE, Predicate.class,
-			Long.TYPE, TimeUnit.class)) //
+		return Try.call(() -> ForkJoinPool.class.getDeclaredConstructor(int.class, ForkJoinWorkerThreadFactory.class,
+			UncaughtExceptionHandler.class, boolean.class, int.class, int.class, int.class, Predicate.class, long.class,
+			TimeUnit.class)) //
 				.toOptional();
 	}
 

platform-tests/src/test/java/org/junit/platform/commons/util/ClassLoaderUtilsTests.java

@@ -108,8 +108,7 @@ void getLocationFromNullFails() {
 
 	@Test
 	void getLocationFromVariousObjectsArePresent() {
-		assertTrue(ClassLoaderUtils.getLocation(void.class).isPresent());
-		assertTrue(ClassLoaderUtils.getLocation(byte.class).isPresent());
+		assertTrue(ClassLoaderUtils.getLocation(getClass()).isPresent());
 		assertTrue(ClassLoaderUtils.getLocation(this).isPresent());
 		assertTrue(ClassLoaderUtils.getLocation("").isPresent());
 		assertTrue(ClassLoaderUtils.getLocation(0).isPresent());

platform-tests/src/test/java/org/junit/platform/commons/util/ReflectionUtilsTests.java

@@ -176,13 +176,13 @@ void isNotFinal() throws Exception {
 	}
 
 	@Test
-	void returnsVoid() throws Exception {
+	void returnsPrimitiveVoid() throws Exception {
 		Class<?> clazz = ClassWithVoidAndNonVoidMethods.class;
-		assertTrue(ReflectionUtils.returnsVoid(clazz.getDeclaredMethod("voidMethod")));
+		assertTrue(ReflectionUtils.returnsPrimitiveVoid(clazz.getDeclaredMethod("voidMethod")));
 
-		assertFalse(ReflectionUtils.returnsVoid(clazz.getDeclaredMethod("methodReturningVoidReference")));
-		assertFalse(ReflectionUtils.returnsVoid(clazz.getDeclaredMethod("methodReturningObject")));
-		assertFalse(ReflectionUtils.returnsVoid(clazz.getDeclaredMethod("methodReturningPrimitive")));
+		assertFalse(ReflectionUtils.returnsPrimitiveVoid(clazz.getDeclaredMethod("methodReturningVoidReference")));
+		assertFalse(ReflectionUtils.returnsPrimitiveVoid(clazz.getDeclaredMethod("methodReturningObject")));
+		assertFalse(ReflectionUtils.returnsPrimitiveVoid(clazz.getDeclaredMethod("methodReturningPrimitive")));
 	}
 
 	@Test

platform-tests/src/test/java/org/junit/platform/engine/support/descriptor/MethodSourceTests.java

@@ -239,7 +239,7 @@ void getJavaMethodFromStringShouldFindVoidMethod() throws Exception {
 
 	@Test
 	void getJavaMethodFromStringShouldFindMethodWithParameter() throws Exception {
-		var testMethod = getClass().getDeclaredMethod("method3", Integer.TYPE);
+		var testMethod = getClass().getDeclaredMethod("method3", int.class);
 		var source = MethodSource.from(getClass().getName(), testMethod.getName(), testMethod.getParameterTypes());
 
 		assertThat(source.getJavaMethod()).isEqualTo(testMethod);
@@ -254,7 +254,7 @@ void getJavaMethodFromStringShouldThrowExceptionIfParameterTypesAreNotSupplied()
 
 	@Test
 	void getJavaMethodFromStringShouldThrowExceptionIfParameterTypesDoNotMatch() {
-		var source = MethodSource.from(getClass().getName(), "method3", Double.TYPE);
+		var source = MethodSource.from(getClass().getName(), "method3", double.class);
 
 		assertThrows(PreconditionViolationException.class, source::getJavaMethod);
 	}