Cleanup after pull-request review junit-team#3890

Make error messaging even more precise. Print out the provider class
that did not return any template invocation contexts.

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

@@ -10,7 +10,6 @@
 
 package org.junit.jupiter.engine.descriptor;
 
-import static java.util.stream.Collectors.joining;
 import static java.util.stream.Collectors.toList;
 import static org.apiguardian.api.API.Status.INTERNAL;
 import static org.junit.jupiter.engine.descriptor.ExtensionUtils.populateNewExtensionRegistryFromExtendWithAnnotation;
@@ -19,6 +18,7 @@
 import java.util.List;
 import java.util.Optional;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.stream.Stream;
 
 import org.apiguardian.api.API;
 import org.junit.jupiter.api.extension.ExecutableInvoker;
@@ -101,18 +101,22 @@ public JupiterEngineExecutionContext execute(JupiterEngineExecutionContext conte
 		List<TestTemplateInvocationContextProvider> providers = validateProviders(extensionContext,
 			context.getExtensionRegistry());
 		AtomicInteger invocationIndex = new AtomicInteger();
-		// @formatter:off
-		providers.stream()
-				.flatMap(provider -> provider.provideTestTemplateInvocationContexts(extensionContext))
-				.map(invocationContext -> createInvocationTestDescriptor(invocationContext, invocationIndex.incrementAndGet()))
-				.filter(Optional::isPresent)
-				.map(Optional::get)
-				.forEach(invocationTestDescriptor -> execute(dynamicTestExecutor, invocationTestDescriptor));
-		// @formatter:on
-		boolean allProvidersMayBeEmpty = providers.stream().allMatch(
-			p -> p.mayReturnZeroInvocationContexts(extensionContext));
-		if (!allProvidersMayBeEmpty) {
-			validateWasAtLeastInvokedOnce(invocationIndex.get(), extensionContext, providers);
+		for (TestTemplateInvocationContextProvider provider : providers) {
+			int initialValue = invocationIndex.get();
+			try (Stream<TestTemplateInvocationContext> templateInvocationContexts = //
+				provider.provideTestTemplateInvocationContexts(extensionContext)) {
+				// @formatter:off
+				templateInvocationContexts
+					.map(invocationContext -> createInvocationTestDescriptor(invocationContext, invocationIndex.incrementAndGet()))
+					.filter(Optional::isPresent)
+					.map(Optional::get)
+					.forEach(invocationTestDescriptor -> execute(dynamicTestExecutor, invocationTestDescriptor));
+			    // @formatter:on
+			}
+			Preconditions.condition(
+				invocationIndex.get() != initialValue || provider.mayReturnZeroInvocationContexts(extensionContext),
+				"Provider [" + provider.getClass().getSimpleName() //
+						+ "] did not provide invocation contexts, but is expected to do so");
 		}
 		return context;
 	}
@@ -145,18 +149,4 @@ private void execute(DynamicTestExecutor dynamicTestExecutor, TestDescriptor tes
 		testDescriptor.setParent(this);
 		dynamicTestExecutor.execute(testDescriptor);
 	}
-
-	private void validateWasAtLeastInvokedOnce(int invocationIndex, ExtensionContext extensionContext,
-			List<TestTemplateInvocationContextProvider> providers) {
-
-		boolean allMayReturnEmptyContext = providers.stream().allMatch(
-			p -> p.mayReturnZeroInvocationContexts(extensionContext));
-
-		Preconditions.condition(invocationIndex > 0 || allMayReturnEmptyContext,
-			() -> "None of the supporting " + TestTemplateInvocationContextProvider.class.getSimpleName() + "s "
-					+ providers.stream().filter(p -> !p.mayReturnZeroInvocationContexts(extensionContext)).map(
-						provider -> provider.getClass().getSimpleName()).collect(joining(", ", "[", "]"))
-					+ " provided a non-empty stream");
-	}
-
 }

junit-jupiter-engine/src/test/java/org/junit/jupiter/engine/TestTemplateInvocationTests.java

@@ -353,9 +353,9 @@ void templateWithSupportingProviderButNoInvocationsReportsFailure() {
 			wrappedInContainerEvents(MyTestTemplateTestCase.class, //
 				event(container("templateWithSupportingProviderButNoInvocations"), started()), //
 				event(container("templateWithSupportingProviderButNoInvocations"),
-					finishedWithFailure(message("None of the supporting TestTemplateInvocationContextProviders ["
+					finishedWithFailure(message("Provider ["
 							+ InvocationContextProviderThatSupportsEverythingButProvidesNothing.class.getSimpleName()
-							+ "] provided a non-empty stream")))));
+							+ "] did not provide invocation contexts, but is expected to do so")))));
 	}
 
 	@Test
@@ -382,9 +382,9 @@ void templateWithMixedProvidersNoInvocationReportsFailure() {
 			wrappedInContainerEvents(MyTestTemplateTestCase.class, //
 				event(container("templateWithMultipleProvidersAllowingAndRestrictingToProvideNothing"), started()), //
 				event(container("templateWithMultipleProvidersAllowingAndRestrictingToProvideNothing"),
-					finishedWithFailure(message("None of the supporting TestTemplateInvocationContextProviders ["
+					finishedWithFailure(message("Provider ["
 							+ InvocationContextProviderThatSupportsEverythingButProvidesNothing.class.getSimpleName()
-							+ "] provided a non-empty stream")))));
+							+ "] did not provide invocation contexts, but is expected to do so")))));
 	}
 
 	@Test