Track dynamic children by index

Author: mpkorstanje

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

@@ -142,15 +142,15 @@ public void close() {
 
 		var workerThread = WorkerThread.get();
 		if (workerThread == null) {
-			return enqueue(testTask).future();
+			return enqueue(testTask, 0).future();
 		}
 
 		if (testTask.getExecutionMode() == SAME_THREAD) {
 			workerThread.executeTask(testTask);
 			return completedFuture(null);
 		}
 
-		var entry = enqueue(testTask);
+		var entry = enqueue(testTask, workerThread.nextChildIndex());
 		workerThread.trackSubmittedChild(entry);
 		return new WorkStealingFuture(entry);
 	}
@@ -172,8 +172,8 @@ public void invokeAll(List<? extends TestTask> testTasks) {
 		workerThread.invokeAll(testTasks);
 	}
 
-	private WorkQueue.Entry enqueue(TestTask testTask) {
-		var entry = workQueue.add(testTask);
+	private WorkQueue.Entry enqueue(TestTask testTask, int index) {
+		var entry = workQueue.add(testTask, index);
 		maybeStartWorker();
 		return entry;
 	}
@@ -548,6 +548,10 @@ private static CompletableFuture<?> toCombinedFuture(List<WorkQueue.Entry> entri
 			return CompletableFuture.allOf(futures);
 		}
 
+		private int nextChildIndex() {
+			return stateStack.element().nextChildIndex();
+		}
+
 		private void trackSubmittedChild(WorkQueue.Entry entry) {
 			stateStack.element().trackSubmittedChild(entry);
 		}
@@ -571,6 +575,8 @@ private void tryToStealWorkFromSubmittedChildren() {
 
 		private static class State {
 
+			private int nextChildIndex = 0;
+
 			@Nullable
 			private List<WorkQueue.Entry> submittedChildren;
 
@@ -586,6 +592,10 @@ private void clearIfEmpty() {
 					submittedChildren = null;
 				}
 			}
+
+			private int nextChildIndex() {
+				return nextChildIndex++;
+			}
 		}
 
 		private enum WorkStealResult {
@@ -645,8 +655,8 @@ private enum BlockingMode {
 	private static class WorkQueue implements Iterable<WorkQueue.Entry> {
 		private final Set<Entry> queue = new ConcurrentSkipListSet<>();
 
-		Entry add(TestTask task) {
-			Entry entry = createEntry(task, 0);
+		Entry add(TestTask task, int index) {
+			Entry entry = createEntry(task, index);
 			LOGGER.trace(() -> "forking: " + entry.task);
 			return doAdd(entry);
 		}

platform-tests/src/test/java/org/junit/platform/engine/support/hierarchical/WorkerThreadPoolHierarchicalTestExecutorServiceTests.java

@@ -586,6 +586,41 @@ void stealsDynamicChildren() throws Exception {
 		assertThat(child2.executionThread).isEqualTo(root.executionThread).isNotEqualTo(child1.executionThread);
 	}
 
+	@Test
+	void executesDynamicChildrenInSubmitOrder() throws Exception {
+		service = new WorkerThreadPoolHierarchicalTestExecutorService(configuration(1, 1));
+
+		var child1 = new TestTaskStub(ExecutionMode.CONCURRENT) //
+				.withName("child1").withLevel(2);
+		var child2 = new TestTaskStub(ExecutionMode.CONCURRENT) //
+				.withName("child2").withLevel(2);
+		var child3 = new TestTaskStub(ExecutionMode.CONCURRENT) //
+				.withName("child3").withLevel(2);
+		var child4 = new TestTaskStub(ExecutionMode.CONCURRENT) //
+				.withName("child3").withLevel(2);
+
+		List<TestTaskStub> children = List.of(child1, child2, child3, child4);
+		Collections.shuffle(children);
+
+		var root = new TestTaskStub(ExecutionMode.SAME_THREAD, () -> {
+			var executor = requiredService();
+			var features = children.stream().map(executor::submit).toList();
+			for (var future : features) {
+				future.get();
+			}
+		}) //
+				.withName("root").withLevel(1);
+
+		service.submit(root).get();
+
+		assertThat(Stream.of(root, child1, child2)) //
+				.allSatisfy(TestTaskStub::assertExecutedSuccessfully);
+
+		assertThat(children) //
+				.extracting(TestTaskStub::startTime) //
+				.isSorted();
+	}
+
 	@Test
 	void stealsNestedDynamicChildren() throws Exception {
 		service = new WorkerThreadPoolHierarchicalTestExecutorService(configuration(2, 2));