Enable NullAway's JSpecify mode and fix resulting issues

gradle/plugins/common/src/main/kotlin/junitbuild.java-nullability-conventions.gradle.kts

@@ -22,6 +22,7 @@ tasks.withType<JavaCompile>().configureEach {
 		disableAllChecks = true
 		nullaway {
 			enable()
+			isJSpecifyMode = true
 		}
 	}
 }

junit-jupiter-api/src/main/java/org/junit/jupiter/api/extension/InvocationInterceptor.java

@@ -78,7 +78,7 @@ public interface InvocationInterceptor extends TestInstantiationAwareExtension {
 	 * @return the result of the invocation; never {@code null}
 	 * @throws Throwable in case of failure
 	 */
-	default <T> T interceptTestClassConstructor(Invocation<T> invocation,
+	default <T> @Nullable T interceptTestClassConstructor(Invocation<T> invocation,
 			ReflectiveInvocationContext<Constructor<T>> invocationContext, ExtensionContext extensionContext)
 			throws Throwable {
 		return invocation.proceed();
@@ -94,7 +94,7 @@ default <T> T interceptTestClassConstructor(Invocation<T> invocation,
 	 * @param extensionContext the current extension context; never {@code null}
 	 * @throws Throwable in case of failures
 	 */
-	default void interceptBeforeAllMethod(Invocation<@Nullable Void> invocation,
+	default void interceptBeforeAllMethod(Invocation<Void> invocation,
 			ReflectiveInvocationContext<Method> invocationContext, ExtensionContext extensionContext) throws Throwable {
 		invocation.proceed();
 	}
@@ -109,7 +109,7 @@ default void interceptBeforeAllMethod(Invocation<@Nullable Void> invocation,
 	 * @param extensionContext the current extension context; never {@code null}
 	 * @throws Throwable in case of failures
 	 */
-	default void interceptBeforeEachMethod(Invocation<@Nullable Void> invocation,
+	default void interceptBeforeEachMethod(Invocation<Void> invocation,
 			ReflectiveInvocationContext<Method> invocationContext, ExtensionContext extensionContext) throws Throwable {
 		invocation.proceed();
 	}
@@ -124,8 +124,8 @@ default void interceptBeforeEachMethod(Invocation<@Nullable Void> invocation,
 	 * @param extensionContext the current extension context; never {@code null}
 	 * @throws Throwable in case of failures
 	 */
-	default void interceptTestMethod(Invocation<@Nullable Void> invocation,
-			ReflectiveInvocationContext<Method> invocationContext, ExtensionContext extensionContext) throws Throwable {
+	default void interceptTestMethod(Invocation<Void> invocation, ReflectiveInvocationContext<Method> invocationContext,
+			ExtensionContext extensionContext) throws Throwable {
 		invocation.proceed();
 	}
 
@@ -143,7 +143,7 @@ default void interceptTestMethod(Invocation<@Nullable Void> invocation,
 	 * @return the result of the invocation; potentially {@code null}
 	 * @throws Throwable in case of failures
 	 */
-	default <T extends @Nullable Object> T interceptTestFactoryMethod(Invocation<T> invocation,
+	default <T> @Nullable T interceptTestFactoryMethod(Invocation<T> invocation,
 			ReflectiveInvocationContext<Method> invocationContext, ExtensionContext extensionContext) throws Throwable {
 		return invocation.proceed();
 	}
@@ -158,7 +158,7 @@ default void interceptTestMethod(Invocation<@Nullable Void> invocation,
 	 * @param extensionContext the current extension context; never {@code null}
 	 * @throws Throwable in case of failures
 	 */
-	default void interceptTestTemplateMethod(Invocation<@Nullable Void> invocation,
+	default void interceptTestTemplateMethod(Invocation<Void> invocation,
 			ReflectiveInvocationContext<Method> invocationContext, ExtensionContext extensionContext) throws Throwable {
 		invocation.proceed();
 	}
@@ -174,8 +174,8 @@ default void interceptTestTemplateMethod(Invocation<@Nullable Void> invocation,
 	 * @throws Throwable in case of failures
 	 */
 	@API(status = STABLE, since = "5.11")
-	default void interceptDynamicTest(Invocation<@Nullable Void> invocation,
-			DynamicTestInvocationContext invocationContext, ExtensionContext extensionContext) throws Throwable {
+	default void interceptDynamicTest(Invocation<Void> invocation, DynamicTestInvocationContext invocationContext,
+			ExtensionContext extensionContext) throws Throwable {
 		invocation.proceed();
 	}
 
@@ -189,7 +189,7 @@ default void interceptDynamicTest(Invocation<@Nullable Void> invocation,
 	 * @param extensionContext the current extension context; never {@code null}
 	 * @throws Throwable in case of failures
 	 */
-	default void interceptAfterEachMethod(Invocation<@Nullable Void> invocation,
+	default void interceptAfterEachMethod(Invocation<Void> invocation,
 			ReflectiveInvocationContext<Method> invocationContext, ExtensionContext extensionContext) throws Throwable {
 		invocation.proceed();
 	}
@@ -204,7 +204,7 @@ default void interceptAfterEachMethod(Invocation<@Nullable Void> invocation,
 	 * @param extensionContext the current extension context; never {@code null}
 	 * @throws Throwable in case of failures
 	 */
-	default void interceptAfterAllMethod(Invocation<@Nullable Void> invocation,
+	default void interceptAfterAllMethod(Invocation<Void> invocation,
 			ReflectiveInvocationContext<Method> invocationContext, ExtensionContext extensionContext) throws Throwable {
 		invocation.proceed();
 	}
@@ -218,14 +218,15 @@ default void interceptAfterAllMethod(Invocation<@Nullable Void> invocation,
 	 * @since 5.5
 	 */
 	@API(status = STABLE, since = "5.10")
-	interface Invocation<T extends @Nullable Object> {
+	interface Invocation<T> {
 
 		/**
 		 * Proceed with this invocation.
 		 *
 		 * @return the result of this invocation; potentially {@code null}.
 		 * @throws Throwable in case the invocation failed
 		 */
+		@Nullable
 		T proceed() throws Throwable;
 
 		/**

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

@@ -409,8 +409,8 @@ private Object invokeTestClassConstructor(Optional<Object> outerInstance, Extens
 			ExtensionContextSupplier extensionContext) {
 
 		Constructor<?> constructor = ReflectionUtils.getDeclaredConstructor(getTestClass());
-		return executableInvoker.invoke(constructor, outerInstance, extensionContext, registry,
-			InvocationInterceptor::interceptTestClassConstructor);
+		return requireNonNull(executableInvoker.invoke(constructor, outerInstance, extensionContext, registry,
+			InvocationInterceptor::interceptTestClassConstructor));
 	}
 
 	private void invokeTestInstancePreConstructCallbacks(TestInstanceFactoryContext factoryContext,

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

@@ -71,7 +71,6 @@ public JupiterEngineExecutionContext execute(JupiterEngineExecutionContext conte
 		return context;
 	}
 
-	@SuppressWarnings("NullAway")
 	private InvocationInterceptor.Invocation<Void> toInvocation() {
 		return () -> {
 			requiredDynamicTest().getExecutable().execute();

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

@@ -60,7 +60,7 @@ public class TestFactoryTestDescriptor extends TestMethodTestDescriptor implemen
 	public static final String DYNAMIC_TEST_SEGMENT_TYPE = "dynamic-test";
 
 	@SuppressWarnings("NullAway")
-	private static final ReflectiveInterceptorCall<Method, @Nullable Object> interceptorCall = InvocationInterceptor::interceptTestFactoryMethod;
+	private static final ReflectiveInterceptorCall<Method, Object> interceptorCall = InvocationInterceptor::interceptTestFactoryMethod;
 	private static final InterceptingExecutableInvoker executableInvoker = new InterceptingExecutableInvoker();
 
 	private final DynamicDescendantFilter dynamicDescendantFilter;

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/execution/InterceptingExecutableInvoker.java

@@ -54,14 +54,14 @@ public class InterceptingExecutableInvoker {
 	 * invocation via all registered {@linkplain InvocationInterceptor
 	 * interceptors}
 	 */
-	public <T> T invoke(Constructor<T> constructor, Optional<Object> outerInstance,
+	public <T> @Nullable T invoke(Constructor<T> constructor, Optional<Object> outerInstance,
 			ExtensionContextSupplier extensionContext, ExtensionRegistry extensionRegistry,
 			ReflectiveInterceptorCall<Constructor<T>, T> interceptorCall) {
 
 		@Nullable
 		Object[] arguments = resolveParameters(constructor, Optional.empty(), outerInstance, extensionContext,
 			extensionRegistry);
-		ConstructorInvocation<T> invocation = new ConstructorInvocation<>(constructor, arguments);
+		ConstructorInvocation<T> invocation = newConstructorInvocation(constructor, arguments);
 		return invoke(invocation, invocation, extensionContext, extensionRegistry, interceptorCall);
 	}
 
@@ -78,40 +78,53 @@ public <T> T invoke(Constructor<T> constructor, Optional<Object> outerInstance,
 	 * @param interceptorCall the call for intercepting this method invocation
 	 * via all registered {@linkplain InvocationInterceptor interceptors}
 	 */
-	public <T> T invoke(Method method, @Nullable Object target, ExtensionContext extensionContext,
+	public <T> @Nullable T invoke(Method method, @Nullable Object target, ExtensionContext extensionContext,
 			ExtensionRegistry extensionRegistry, ReflectiveInterceptorCall<Method, T> interceptorCall) {
 
 		@SuppressWarnings({ "unchecked", "rawtypes" })
 		Optional<Object> optionalTarget = (target instanceof Optional optional ? optional
 				: Optional.ofNullable(target));
 		@Nullable
 		Object[] arguments = resolveParameters(method, optionalTarget, extensionContext, extensionRegistry);
-		MethodInvocation<T> invocation = new MethodInvocation<>(method, optionalTarget, arguments);
+		MethodInvocation<T> invocation = newMethodInvocation(method, optionalTarget, arguments);
 		return invoke(invocation, invocation, extensionContext, extensionRegistry, interceptorCall);
 	}
 
-	private <E extends Executable, T> T invoke(Invocation<T> originalInvocation,
+	private <E extends Executable, T extends @Nullable Object> @Nullable T invoke(Invocation<T> originalInvocation,
 			ReflectiveInvocationContext<E> invocationContext, ExtensionContext extensionContext,
 			ExtensionRegistry extensionRegistry, ReflectiveInterceptorCall<E, T> call) {
 		return interceptorChain.invoke(originalInvocation, extensionRegistry, (interceptor,
 				wrappedInvocation) -> call.apply(interceptor, wrappedInvocation, invocationContext, extensionContext));
 	}
 
-	private <E extends Executable, T> T invoke(Invocation<T> originalInvocation,
+	private <E extends Executable, T> @Nullable T invoke(Invocation<T> originalInvocation,
 			ReflectiveInvocationContext<E> invocationContext, ExtensionContextSupplier extensionContext,
 			ExtensionRegistry extensionRegistry, ReflectiveInterceptorCall<E, T> call) {
 		return interceptorChain.invoke(originalInvocation, extensionRegistry,
 			(interceptor, wrappedInvocation) -> call.apply(interceptor, wrappedInvocation, invocationContext,
 				extensionContext.get(interceptor)));
 	}
 
-	public interface ReflectiveInterceptorCall<E extends Executable, T extends @Nullable Object> {
+	@SuppressWarnings("NullAway")
+	private static <T> ConstructorInvocation<T> newConstructorInvocation(Constructor<T> constructor,
+			@Nullable Object[] arguments) {
+		return new ConstructorInvocation<>(constructor, arguments);
+	}
+
+	@SuppressWarnings("NullAway")
+	private static <T> MethodInvocation<T> newMethodInvocation(Method method, Optional<Object> optionalTarget,
+			@Nullable Object[] arguments) {
+		return new MethodInvocation<>(method, optionalTarget, arguments);
+	}
 
+	public interface ReflectiveInterceptorCall<E extends Executable, T> {
+
+		@Nullable
 		T apply(InvocationInterceptor interceptor, Invocation<T> invocation,
 				ReflectiveInvocationContext<E> invocationContext, ExtensionContext extensionContext) throws Throwable;
 
 		@SuppressWarnings("NullAway")
-		static ReflectiveInterceptorCall<Method, @Nullable Void> ofVoidMethod(VoidMethodInterceptorCall call) {
+		static ReflectiveInterceptorCall<Method, Void> ofVoidMethod(VoidMethodInterceptorCall call) {
 			return ((interceptorChain, invocation, invocationContext, extensionContext) -> {
 				call.apply(interceptorChain, invocation, invocationContext, extensionContext);
 				return null;

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/execution/InvocationInterceptorChain.java

@@ -30,15 +30,16 @@
 @API(status = INTERNAL, since = "5.5")
 public class InvocationInterceptorChain {
 
-	public <T> T invoke(Invocation<T> invocation, ExtensionRegistry extensionRegistry, InterceptorCall<T> call) {
+	public <T> @Nullable T invoke(Invocation<T> invocation, ExtensionRegistry extensionRegistry,
+			InterceptorCall<T> call) {
 		List<InvocationInterceptor> interceptors = extensionRegistry.getExtensions(InvocationInterceptor.class);
 		if (interceptors.isEmpty()) {
 			return proceed(invocation);
 		}
 		return chainAndInvoke(invocation, call, interceptors);
 	}
 
-	private <T> T chainAndInvoke(Invocation<T> invocation, InterceptorCall<T> call,
+	private <T> @Nullable T chainAndInvoke(Invocation<T> invocation, InterceptorCall<T> call,
 			List<InvocationInterceptor> interceptors) {
 
 		ValidatingInvocation<T> validatingInvocation = new ValidatingInvocation<>(invocation, interceptors);
@@ -60,7 +61,7 @@ private <T> Invocation<T> chainInterceptors(Invocation<T> invocation, Intercepto
 		return result;
 	}
 
-	private <T> T proceed(Invocation<T> invocation) {
+	private <T> @Nullable T proceed(Invocation<T> invocation) {
 		try {
 			return invocation.proceed();
 		}
@@ -70,12 +71,13 @@ private <T> T proceed(Invocation<T> invocation) {
 	}
 
 	@FunctionalInterface
-	public interface InterceptorCall<T extends @Nullable Object> {
+	public interface InterceptorCall<T> {
 
+		@Nullable
 		T apply(InvocationInterceptor interceptor, Invocation<T> invocation) throws Throwable;
 
 		@SuppressWarnings("NullAway")
-		static InterceptorCall<@Nullable Void> ofVoid(VoidInterceptorCall call) {
+		static InterceptorCall<Void> ofVoid(VoidInterceptorCall call) {
 			return ((interceptorChain, invocation) -> {
 				call.apply(interceptorChain, invocation);
 				return null;
@@ -87,15 +89,15 @@ public interface InterceptorCall<T extends @Nullable Object> {
 	@FunctionalInterface
 	public interface VoidInterceptorCall {
 
-		void apply(InvocationInterceptor interceptor, Invocation<@Nullable Void> invocation) throws Throwable;
+		void apply(InvocationInterceptor interceptor, Invocation<Void> invocation) throws Throwable;
 
 	}
 
 	private record InterceptedInvocation<T>(Invocation<T> invocation, InterceptorCall<T> call,
 			InvocationInterceptor interceptor) implements Invocation<T> {
 
 		@Override
-		public T proceed() throws Throwable {
+		public @Nullable T proceed() throws Throwable {
 			return call.apply(interceptor, invocation);
 		}
 
@@ -119,7 +121,7 @@ private static class ValidatingInvocation<T extends @Nullable Object> implements
 		}
 
 		@Override
-		public T proceed() throws Throwable {
+		public @Nullable T proceed() throws Throwable {
 			markInvokedOrSkipped();
 			return delegate.proceed();
 		}

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/execution/NamespaceAwareStore.java

@@ -39,26 +39,30 @@ public NamespaceAwareStore(NamespacedHierarchicalStore<Namespace> valuesStore, N
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public @Nullable Object get(Object key) {
 		Preconditions.notNull(key, "key must not be null");
 		return accessStore(() -> this.valuesStore.get(this.namespace, key));
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public <T> @Nullable T get(Object key, Class<T> requiredType) {
 		Preconditions.notNull(key, "key must not be null");
 		Preconditions.notNull(requiredType, "requiredType must not be null");
 		return accessStore(() -> this.valuesStore.get(this.namespace, key, requiredType));
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public <K, V> @Nullable Object getOrComputeIfAbsent(K key, Function<K, V> defaultCreator) {
 		Preconditions.notNull(key, "key must not be null");
 		Preconditions.notNull(defaultCreator, "defaultCreator function must not be null");
 		return accessStore(() -> this.valuesStore.getOrComputeIfAbsent(this.namespace, key, defaultCreator));
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public <K, V> @Nullable V getOrComputeIfAbsent(K key, Function<K, V> defaultCreator, Class<V> requiredType) {
 		Preconditions.notNull(key, "key must not be null");
 		Preconditions.notNull(defaultCreator, "defaultCreator function must not be null");
@@ -68,18 +72,21 @@ public NamespaceAwareStore(NamespacedHierarchicalStore<Namespace> valuesStore, N
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public void put(Object key, @Nullable Object value) {
 		Preconditions.notNull(key, "key must not be null");
 		accessStore(() -> this.valuesStore.put(this.namespace, key, value));
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public @Nullable Object remove(Object key) {
 		Preconditions.notNull(key, "key must not be null");
 		return accessStore(() -> this.valuesStore.remove(this.namespace, key));
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public <T> @Nullable T remove(Object key, Class<T> requiredType) {
 		Preconditions.notNull(key, "key must not be null");
 		Preconditions.notNull(requiredType, "requiredType must not be null");

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/extension/SeparateThreadTimeoutInvocation.java

@@ -37,6 +37,7 @@ class SeparateThreadTimeoutInvocation<T extends @Nullable Object> implements Inv
 	}
 
 	@Override
+	@SuppressWarnings("NullAway")
 	public T proceed() throws Throwable {
 		return assertTimeoutPreemptively(timeout.toDuration(), delegate::proceed, descriptionSupplier,
 			(__, messageSupplier, cause, testThread) -> {

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/extension/TimeoutExtension.java

@@ -103,7 +103,7 @@ public void interceptTestTemplateMethod(Invocation<Void> invocation,
 	}
 
 	@Override
-	public <T> T interceptTestFactoryMethod(Invocation<T> invocation,
+	public <T> @Nullable T interceptTestFactoryMethod(Invocation<T> invocation,
 			ReflectiveInvocationContext<Method> invocationContext, ExtensionContext extensionContext) throws Throwable {
 
 		return interceptTestableMethod(invocation, invocationContext, extensionContext,
@@ -145,7 +145,7 @@ private Optional<ThreadMode> readTimeoutThreadModeFromAnnotation(Optional<Annota
 		return AnnotationSupport.findAnnotation(element, Timeout.class).map(Timeout::threadMode);
 	}
 
-	private <T> T interceptTestableMethod(Invocation<T> invocation,
+	private <T> @Nullable T interceptTestableMethod(Invocation<T> invocation,
 			ReflectiveInvocationContext<Method> invocationContext, ExtensionContext extensionContext,
 			TimeoutProvider defaultTimeoutProvider) throws Throwable {
 
@@ -154,7 +154,7 @@ private <T> T interceptTestableMethod(Invocation<T> invocation,
 		return intercept(invocation, invocationContext, extensionContext, timeout, defaultTimeoutProvider);
 	}
 
-	private <T> T intercept(Invocation<T> invocation, ReflectiveInvocationContext<Method> invocationContext,
+	private <T> @Nullable T intercept(Invocation<T> invocation, ReflectiveInvocationContext<Method> invocationContext,
 			ExtensionContext extensionContext, @Nullable TimeoutDuration explicitTimeout,
 			TimeoutProvider defaultTimeoutProvider) throws Throwable {
 

junit-jupiter-engine/src/main/java/org/junit/jupiter/engine/support/MethodReflectionUtils.java

@@ -38,6 +38,7 @@ public static Type getGenericReturnType(Method method) {
 				: method.getGenericReturnType();
 	}
 
+	@SuppressWarnings("NullAway")
 	public static @Nullable Object invoke(Method method, @Nullable Object target, @Nullable Object[] arguments) {
 		if (isKotlinSuspendingFunction(method)) {
 			return invokeKotlinSuspendingFunction(method, target, arguments);

junit-jupiter-params/src/main/java/org/junit/jupiter/params/ResolutionCache.java

@@ -36,7 +36,7 @@ class Concurrent implements ResolutionCache {
 		private final Map<ParameterDeclaration, Object> cache = new ConcurrentHashMap<>();
 
 		@Override
-		public Object resolve(ParameterDeclaration declaration, Supplier<Object> resolver) {
+		public @Nullable Object resolve(ParameterDeclaration declaration, Supplier<@Nullable Object> resolver) {
 			return cache.computeIfAbsent(declaration, __ -> resolver.get());
 		}
 	}