Prune stack traces up to test method (#4829)

Everything before the test method is invoked is not informative for the
end user. Discarding that part of the stacktrace removes a few more
frames.

Additionally, when pruning consider the source of the test descriptor
not merely its ancestors.

Fixes #4828.

Author: mpkorstanje

documentation/src/docs/asciidoc/release-notes/release-notes-6.0.0-RC1.adoc

@@ -26,8 +26,7 @@ repository on GitHub.
 [[release-notes-6.0.0-RC1-junit-platform-new-features-and-improvements]]
 ==== New Features and Improvements
 
-* ❓
-
+* Prune stack traces up to test or lifecycle method
 
 [[release-notes-6.0.0-RC1-junit-jupiter]]
 === JUnit Jupiter

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

@@ -97,11 +97,15 @@ public static String readStackTrace(Throwable throwable) {
 	}
 
 	/**
-	 * Prune the stack trace of the supplied {@link Throwable} by removing
-	 * {@linkplain StackTraceElement stack trace elements} from the {@code org.junit},
-	 * {@code jdk.internal.reflect}, and {@code sun.reflect} packages. If a
-	 * {@code StackTraceElement} matching one of the supplied {@code classNames}
-	 * is encountered, all subsequent elements in the stack trace will be retained.
+	 * Prune the stack trace of the supplied {@link Throwable}.
+	 *
+	 * <p>Prune all {@linkplain StackTraceElement stack trace elements} up one
+	 * of the supplied {@code classNames} are pruned. All subsequent elements
+	 * in the stack trace will be retained.
+	 *
+	 * <p>If the {@code classNames} do not match any of the stacktrace elements
+	 * then the {@code org.junit}, {@code jdk.internal.reflect}, and
+	 * {@code sun.reflect} packages are pruned.
 	 *
 	 * <p>Additionally, all elements prior to and including the first JUnit Platform
 	 * Launcher call will be removed.
@@ -128,6 +132,9 @@ public static void pruneStackTrace(Throwable throwable, List<String> classNames)
 			String className = element.getClassName();
 
 			if (classNames.contains(className)) {
+				// We found the test
+				// everything before that is not informative.
+				prunedStackTrace.clear();
 				// Include all elements called by the test
 				prunedStackTrace.addAll(stackTrace.subList(i, stackTrace.size()));
 				break;

junit-platform-launcher/src/main/java/org/junit/platform/launcher/core/StackTracePruningEngineExecutionListener.java

@@ -13,6 +13,7 @@
 import java.util.List;
 import java.util.Objects;
 import java.util.Optional;
+import java.util.stream.Stream;
 
 import org.junit.platform.commons.util.ExceptionUtils;
 import org.junit.platform.engine.EngineExecutionListener;
@@ -46,8 +47,9 @@ public void executionFinished(TestDescriptor testDescriptor, TestExecutionResult
 	}
 
 	private static List<String> getTestClassNames(TestDescriptor testDescriptor) {
-		return testDescriptor.getAncestors() //
-				.stream() //
+		Stream<? extends TestDescriptor> self = Stream.of(testDescriptor);
+		Stream<? extends TestDescriptor> ancestors = testDescriptor.getAncestors().stream();
+		return Stream.concat(self, ancestors) //
 				.map(TestDescriptor::getSource) //
 				.flatMap(Optional::stream) //
 				.map(source -> {

platform-tests/src/test/java/org/junit/platform/StackTracePruningTests.java

@@ -115,7 +115,7 @@ void shouldAlwaysKeepJupiterAssumptionStackTraceElement() {
 	}
 
 	@Test
-	void shouldKeepEverythingAfterTestCall() {
+	void shouldKeepExactlyEverythingAfterTestCall() {
 		EngineExecutionResults results = EngineTestKit.engine("junit-jupiter") //
 				.configurationParameter("junit.platform.stacktrace.pruning.enabled", "true") //
 				.selectors(selectMethod(FailingTestTestCase.class, "failingAssertion")) //
@@ -128,15 +128,14 @@ void shouldKeepEverythingAfterTestCall() {
 					\\Qorg.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:\\E.+
 					\\Qorg.junit.jupiter.api.Assertions.fail(Assertions.java:\\E.+
 					\\Qorg.junit.platform.StackTracePruningTests$FailingTestTestCase.failingAssertion(StackTracePruningTests.java:\\E.+
-					>>>>
 					""");
 	}
 
 	@ParameterizedTest
 	@ValueSource(strings = { "org.junit.platform.StackTracePruningTests$FailingBeforeEachTestCase",
 			"org.junit.platform.StackTracePruningTests$FailingBeforeEachTestCase$NestedTestCase",
 			"org.junit.platform.StackTracePruningTests$FailingBeforeEachTestCase$NestedTestCase$NestedNestedTestCase" })
-	void shouldKeepEverythingAfterLifecycleMethodCall(Class<?> methodClass) {
+	void shouldKeepExactlyEverythingAfterLifecycleMethodCall(Class<?> methodClass) {
 		EngineExecutionResults results = EngineTestKit.engine("junit-jupiter") //
 				.configurationParameter("junit.platform.stacktrace.pruning.enabled", "true") //
 				.selectors(selectMethod(methodClass, "test")) //
@@ -149,7 +148,6 @@ void shouldKeepEverythingAfterLifecycleMethodCall(Class<?> methodClass) {
 					\\Qorg.junit.jupiter.api.AssertionUtils.fail(AssertionUtils.java:\\E.+
 					\\Qorg.junit.jupiter.api.Assertions.fail(Assertions.java:\\E.+
 					\\Qorg.junit.platform.StackTracePruningTests$FailingBeforeEachTestCase.setUp(StackTracePruningTests.java:\\E.+
-					>>>>
 					""");
 	}