Adversarial review on test porting plan

tests/co/group_edge_tests.cpp

@@ -88,75 +88,17 @@ CalleeVoidInvoker voidMemberAfterDelay(int delayMilliseconds)
 	co_return;
 }
 
-int readCompletedLabel(CalleeIntInvoker &invoker)
+CalleeIntInvoker waitRecordThreadAndReturnLabel(
+	int timerLabelMilliseconds,
+	sscl::tests::CrossThreadTrace &trace)
 {
-	return invoker.completedReturnValues().myReturnValue;
-}
-
-void assertCompleted(
-	const sscl::co::Group::SettlementDescriptor &descriptor,
-	int expectedLabel)
-{
-	if (descriptor.type
-		!= sscl::co::Group::SettlementDescriptor::TypeE::COMPLETED) {
-		throw std::runtime_error("expected completed settlement");
-	}
-
-	if (readCompletedLabel(descriptor.invokerAs<CalleeIntInvoker>())
-		!= expectedLabel) {
-		throw std::runtime_error("settlement label mismatch");
-	}
-}
-
-void assertRuntimeErrorSettlement(
-	const sscl::co::Group::SettlementDescriptor &descriptor)
-{
-	if (descriptor.type
-		!= sscl::co::Group::SettlementDescriptor::TypeE::EXCEPTION_THROWN) {
-		throw std::runtime_error("expected exception settlement");
-	}
-
-	try {
-		std::rethrow_exception(descriptor.calleeException);
-	}
-	catch (const std::runtime_error &runtimeError) {
-		if (std::string(runtimeError.what()) != expectedThrowMessage) {
-			throw std::runtime_error("unexpected exception message");
-		}
-		return;
-	}
-
-	throw std::runtime_error("expected runtime_error settlement");
-}
-
-void assertIntExceptionSettlement(
-	const sscl::co::Group::SettlementDescriptor &descriptor)
-{
-	if (descriptor.type
-		!= sscl::co::Group::SettlementDescriptor::TypeE::EXCEPTION_THROWN) {
-		throw std::runtime_error("expected int exception settlement");
-	}
-
-	try {
-		std::rethrow_exception(descriptor.calleeException);
-	}
-	catch (int caughtValue) {
-		if (caughtValue != expectedNonStdThrowValue) {
-			throw std::runtime_error("unexpected int exception value");
-		}
-		return;
-	}
-
-	throw std::runtime_error("expected int exception settlement");
-}
-
-void assertEmptyGroupCoAwaitError(const std::runtime_error &runtimeError)
-{
-	constexpr const char *expectedEmptyGroupCoAwaitMessage =
-		"co_await: Group has no member invokers; call add() before awaiting";
-	if (std::string(runtimeError.what()) != expectedEmptyGroupCoAwaitMessage) {
-		throw std::runtime_error("unexpected empty-group error message");
-	}
+	const boost::system::error_code waitError =
+		co_await sscl::tests::DeadlineTimerAwaiter{
+			sscl::ComponentThread::getSelf()->getIoContext(),
+			timerLabelMilliseconds};
+	sscl::tests::throwIfTimerWaitFailed(waitError);
+	trace.recordCalleeExecutionThread();
+	co_return timerLabelMilliseconds;
 }
 
 sscl::co::ViralNonPostingInvoker<void> waitOnCallerThread(int delayMilliseconds)
@@ -188,11 +130,15 @@ CallerDriver mixedSuccessAndFailureAwaitFirstThenAll(
 
 	if (firstDescriptor.type
 		== sscl::co::Group::SettlementDescriptor::TypeE::COMPLETED) {
-		assertCompleted(firstDescriptor, 1);
+		sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+			firstDescriptor,
+			1);
 	}
 	else if (firstDescriptor.type
 		== sscl::co::Group::SettlementDescriptor::TypeE::EXCEPTION_THROWN) {
-		assertRuntimeErrorSettlement(firstDescriptor);
+		sscl::tests::requireRuntimeErrorSettlement(
+			firstDescriptor,
+			expectedThrowMessage);
 	}
 	else {
 		throw std::runtime_error("first settlement has unexpected type");
@@ -212,12 +158,16 @@ CallerDriver mixedSuccessAndFailureAwaitFirstThenAll(
 		if (descriptor.type
 			== sscl::co::Group::SettlementDescriptor::TypeE::COMPLETED) {
 			++completedCount;
-			assertCompleted(descriptor, 1);
+			sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+				descriptor,
+				1);
 		}
 		else if (descriptor.type
 			== sscl::co::Group::SettlementDescriptor::TypeE::EXCEPTION_THROWN) {
 			++exceptionCount;
-			assertRuntimeErrorSettlement(descriptor);
+			sscl::tests::requireRuntimeErrorSettlement(
+				descriptor,
+				expectedThrowMessage);
 		}
 	}
 
@@ -241,7 +191,9 @@ CallerDriver singleMemberAwaitFirstThenAll(
 
 	auto awaitFirst = group.getAwaitFirstSettlementInvoker();
 	auto [firstDescriptor, allAfterFirst] = co_await awaitFirst;
-	assertCompleted(firstDescriptor, delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		firstDescriptor,
+		delayShortMs);
 
 	if (!group.allInvokersSettled() || allAfterFirst.size() != 1) {
 		throw std::runtime_error("single member state mismatch");
@@ -254,7 +206,9 @@ CallerDriver singleMemberAwaitFirstThenAll(
 		throw std::runtime_error("single member await-all count mismatch");
 	}
 
-	assertCompleted(allDescriptors[0], delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		allDescriptors[0],
+		delayShortMs);
 	co_return;
 }
 
@@ -282,7 +236,9 @@ CallerDriver allCompleteBeforeCoAwait(
 
 	auto awaitFirst = group.getAwaitFirstSettlementInvoker();
 	auto [firstDescriptor, allAfterFirst] = co_await awaitFirst;
-	assertCompleted(firstDescriptor, 10);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		firstDescriptor,
+		10);
 
 	auto awaitAll = group.getAwaitAllSettlementsInvoker();
 	auto &allDescriptors = co_await awaitAll;
@@ -294,13 +250,13 @@ CallerDriver allCompleteBeforeCoAwait(
 	co_return;
 }
 
-std::thread startAddWhileGroupAwaiterSuspendedProbe(
+std::jthread startAddWhileGroupAwaiterSuspendedProbe(
 	sscl::co::Group &group,
 	CalleeIntInvoker &lateInvoker,
 	std::atomic<bool> &groupIsAwaitingAll,
 	std::atomic<bool> &addWasRejected)
 {
-	return std::thread(
+	return std::jthread(
 		[&]()
 		{
 			while (!groupIsAwaitingAll.load(std::memory_order_acquire)) {
@@ -343,7 +299,7 @@ CallerDriver addWhileAwaitAllSuspended(
 	group.add(slowInvokerA);
 	group.add(slowInvokerB);
 
-	std::thread addProbeThread = startAddWhileGroupAwaiterSuspendedProbe(
+	std::jthread addProbeThread = startAddWhileGroupAwaiterSuspendedProbe(
 		group,
 		lateInvoker,
 		groupIsAwaitingAll,
@@ -390,12 +346,16 @@ CallerDriver awaitAllOnlyMixedOutcomes(
 		if (descriptor.type
 			== sscl::co::Group::SettlementDescriptor::TypeE::COMPLETED) {
 			++completedCount;
-			assertCompleted(descriptor, 7);
+			sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+				descriptor,
+				7);
 		}
 		else if (descriptor.type
 			== sscl::co::Group::SettlementDescriptor::TypeE::EXCEPTION_THROWN) {
 			++exceptionCount;
-			assertRuntimeErrorSettlement(descriptor);
+			sscl::tests::requireRuntimeErrorSettlement(
+				descriptor,
+				expectedThrowMessage);
 		}
 	}
 
@@ -446,7 +406,7 @@ CallerDriver emptyGroupAwaitAllThrows(
 		(void)co_await group.getAwaitAllSettlementsInvoker();
 	}
 	catch (const std::runtime_error &runtimeError) {
-		assertEmptyGroupCoAwaitError(runtimeError);
+		sscl::tests::requireEmptyGroupError(runtimeError);
 		co_return;
 	}
 
@@ -466,7 +426,7 @@ CallerDriver emptyGroupAwaitFirstThrows(
 		(void)co_await group.getAwaitFirstSettlementInvoker();
 	}
 	catch (const std::runtime_error &runtimeError) {
-		assertEmptyGroupCoAwaitError(runtimeError);
+		sscl::tests::requireEmptyGroupError(runtimeError);
 		co_return;
 	}
 
@@ -496,9 +456,10 @@ CallerDriver wrongAwaitInvokerOrder(
 	}
 
 	auto [firstDescriptor, allAfterFirst] = co_await awaitFirstHandle;
-	assertCompleted(
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
 		firstDescriptor,
-		readCompletedLabel(firstDescriptor.invokerAs<CalleeIntInvoker>()));
+		sscl::tests::completedIntValue(
+			firstDescriptor.invokerAs<CalleeIntInvoker>()));
 
 	if (!group.firstInvokerSettled() || allAfterFirst.size() != 2) {
 		throw std::runtime_error("wrong-order await-first state mismatch");
@@ -524,8 +485,12 @@ CallerDriver doubleCoAwaitSameAwaitFirst(
 	auto [firstDescriptorA, allAfterFirstA] = co_await awaitFirst;
 	auto [firstDescriptorB, allAfterFirstB] = co_await awaitFirst;
 
-	assertCompleted(firstDescriptorA, delayShortMs);
-	assertCompleted(firstDescriptorB, delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		firstDescriptorA,
+		delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		firstDescriptorB,
+		delayShortMs);
 
 	if (&firstDescriptorA.invokerAs<CalleeIntInvoker>()
 		!= &firstDescriptorB.invokerAs<CalleeIntInvoker>()) {
@@ -558,8 +523,12 @@ CallerDriver doubleCoAwaitSameAwaitAll(
 		throw std::runtime_error("double await-all count mismatch");
 	}
 
-	assertCompleted(allDescriptorsA[0], delayShortMs);
-	assertCompleted(allDescriptorsB[0], delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		allDescriptorsA[0],
+		delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		allDescriptorsB[0],
+		delayShortMs);
 	co_return;
 }
 
@@ -579,11 +548,15 @@ CallerDriver twoAwaitFirstHandlesSequentially(
 
 	auto awaitFirstA = group.getAwaitFirstSettlementInvoker();
 	auto [firstDescriptorA, allAfterFirstA] = co_await awaitFirstA;
-	assertCompleted(firstDescriptorA, delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		firstDescriptorA,
+		delayShortMs);
 
 	auto awaitFirstB = group.getAwaitFirstSettlementInvoker();
 	auto [firstDescriptorB, allAfterFirstB] = co_await awaitFirstB;
-	assertCompleted(firstDescriptorB, delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		firstDescriptorB,
+		delayShortMs);
 
 	if (&firstDescriptorA.invokerAs<CalleeIntInvoker>()
 		!= &firstDescriptorB.invokerAs<CalleeIntInvoker>()) {
@@ -620,7 +593,7 @@ CallerDriver addSecondWaveAfterAwaitAll(
 
 	co_await waitOnCallerThread(delayShortMs);
 
-	if (readCompletedLabel(wave2Immediate)
+	if (sscl::tests::completedIntValue(wave2Immediate)
 		!= wave2ImmediateSettlementLabel) {
 		throw std::runtime_error("wave-2 immediate member did not complete");
 	}
@@ -656,7 +629,9 @@ CallerDriver shortTimerAddedAfterLongStillWinsRace(
 	auto awaitFirst = group.getAwaitFirstSettlementInvoker();
 	auto [firstDescriptor, allAfterFirst] = co_await awaitFirst;
 
-	assertCompleted(firstDescriptor, delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		firstDescriptor,
+		delayShortMs);
 
 	if (&firstDescriptor.invokerAs<CalleeIntInvoker>() != &shortInvoker) {
 		throw std::runtime_error("short timer should win first settlement");
@@ -684,7 +659,9 @@ CallerDriver nonStdExceptionSettlement(
 		throw std::runtime_error("non-std exception count mismatch");
 	}
 
-	assertIntExceptionSettlement(allDescriptors[0]);
+	sscl::tests::requireIntExceptionSettlement(
+		allDescriptors[0],
+		expectedNonStdThrowValue);
 
 	try {
 		group.checkForAndReThrowGroupExceptions();
@@ -738,11 +715,14 @@ CallerDriver returnValuesRemainReadableAfterAwaitFirst(
 	auto awaitFirst = group.getAwaitFirstSettlementInvoker();
 	auto [firstDescriptor, allAfterFirst] = co_await awaitFirst;
 
-	assertCompleted(firstDescriptor, delayShortMs);
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		firstDescriptor,
+		delayShortMs);
 
-	const int fastLabelFromDescriptor = readCompletedLabel(
+	const int fastLabelFromDescriptor = sscl::tests::completedIntValue(
 		firstDescriptor.invokerAs<CalleeIntInvoker>());
-	const int fastLabelFromLocal = readCompletedLabel(fastInvoker);
+	const int fastLabelFromLocal =
+		sscl::tests::completedIntValue(fastInvoker);
 
 	if (fastLabelFromDescriptor != fastLabelFromLocal) {
 		throw std::runtime_error("descriptor/local return value mismatch");
@@ -756,6 +736,35 @@ CallerDriver returnValuesRemainReadableAfterAwaitFirst(
 	co_return;
 }
 
+CallerDriver groupMemberRunsOnCalleeAndAwaitResumesOnCaller(
+	std::exception_ptr &exceptionPtr,
+	std::function<void()> completion,
+	sscl::tests::CrossThreadTrace &trace)
+{
+	(void)exceptionPtr;
+	(void)completion;
+
+	sscl::co::Group group;
+	CalleeIntInvoker memberInvoker = waitRecordThreadAndReturnLabel(
+		delayShortMs,
+		trace);
+	group.add(memberInvoker);
+
+	auto awaitFirst = group.getAwaitFirstSettlementInvoker();
+	auto [firstDescriptor, allAfterFirst] = co_await awaitFirst;
+	trace.recordAwaitResumeThread();
+
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
+		firstDescriptor,
+		delayShortMs);
+
+	if (allAfterFirst.size() != 1) {
+		throw std::runtime_error("cross-thread group trace count mismatch");
+	}
+
+	co_return;
+}
+
 class GroupEdgeTest
 :	public ::testing::Test
 {
@@ -816,6 +825,26 @@ RUN_GROUP_EDGE_SCENARIO(
 	ReturnValuesRemainReadableAfterAwaitFirst,
 	returnValuesRemainReadableAfterAwaitFirst)
 
+TEST_F(GroupEdgeTest, SuspendingMemberRunsOnCalleeAndAwaitResumesOnCaller)
+{
+	sscl::tests::CrossThreadTrace trace;
+
+	runScenario(
+		[&trace](
+			std::exception_ptr &exceptionPtr,
+			std::function<void()> completion)
+		{
+			return groupMemberRunsOnCalleeAndAwaitResumesOnCaller(
+				exceptionPtr,
+				std::move(completion),
+				trace);
+		});
+
+	EXPECT_EQ(trace.calleeExecutionThread(), threads.callee().osThreadId());
+	EXPECT_EQ(trace.awaitResumeThread(), threads.caller().osThreadId());
+	EXPECT_NE(trace.calleeExecutionThread(), trace.awaitResumeThread());
+}
+
 TEST_F(GroupEdgeTest, NonViralVoidGroupTemplateInstantiates)
 {
 	GTEST_SKIP()

tests/co/group_timer_tests.cpp

@@ -1,8 +1,11 @@
 #include <chrono>
 #include <exception>
 #include <functional>
+#include <map>
+#include <mutex>
 #include <stdexcept>
 #include <string>
+#include <thread>
 
 #include <gtest/gtest.h>
 
@@ -36,19 +39,77 @@ using CalleeIntInvoker =
 using Clock = std::chrono::steady_clock;
 using Ms = std::chrono::milliseconds;
 
-CalleeIntInvoker waitDeadlineTimer(int timerLabelMilliseconds)
+class GroupTimerThreadTrace
+{
+public:
+	void recordTimerCompletionThread(int timerLabelMilliseconds)
+	{
+		std::lock_guard<std::mutex> guard(mutex);
+		timerCompletionThreads[timerLabelMilliseconds] =
+			std::this_thread::get_id();
+	}
+
+	void recordAwaitFirstResumeThread()
+	{
+		std::lock_guard<std::mutex> guard(mutex);
+		awaitFirstResumeThread = std::this_thread::get_id();
+	}
+
+	void recordAwaitAllResumeThread()
+	{
+		std::lock_guard<std::mutex> guard(mutex);
+		awaitAllResumeThread = std::this_thread::get_id();
+	}
+
+	std::thread::id timerCompletionThread(int timerLabelMilliseconds) const
+	{
+		std::lock_guard<std::mutex> guard(mutex);
+		const auto iterator =
+			timerCompletionThreads.find(timerLabelMilliseconds);
+
+		if (iterator == timerCompletionThreads.end()) {
+			throw std::runtime_error("Missing timer completion thread trace");
+		}
+
+		return iterator->second;
+	}
+
+	std::thread::id awaitFirstThread() const
+	{
+		std::lock_guard<std::mutex> guard(mutex);
+		return awaitFirstResumeThread;
+	}
+
+	std::thread::id awaitAllThread() const
+	{
+		std::lock_guard<std::mutex> guard(mutex);
+		return awaitAllResumeThread;
+	}
+
+private:
+	mutable std::mutex mutex;
+	std::map<int, std::thread::id> timerCompletionThreads;
+	std::thread::id awaitFirstResumeThread;
+	std::thread::id awaitAllResumeThread;
+};
+
+CalleeIntInvoker waitDeadlineTimer(
+	int timerLabelMilliseconds,
+	GroupTimerThreadTrace &trace)
 {
 	const boost::system::error_code waitError =
 		co_await sscl::tests::DeadlineTimerAwaiter{
 			sscl::ComponentThread::getSelf()->getIoContext(),
 			timerLabelMilliseconds};
 	sscl::tests::throwIfTimerWaitFailed(waitError);
+	trace.recordTimerCompletionThread(timerLabelMilliseconds);
 	co_return timerLabelMilliseconds;
 }
 
 CalleeIntInvoker waitCancelableDeadlineTimer(
 	int timerLabelMilliseconds,
-	sscl::tests::CancelableDeadlineTimerRegistry &registry)
+	sscl::tests::CancelableDeadlineTimerRegistry &registry,
+	GroupTimerThreadTrace &trace)
 {
 	const boost::system::error_code waitError =
 		co_await sscl::tests::RegisteredDeadlineTimerAwaiter{
@@ -58,10 +119,12 @@ CalleeIntInvoker waitCancelableDeadlineTimer(
 			registry};
 
 	if (sscl::tests::timerWasCanceled(waitError)) {
+		trace.recordTimerCompletionThread(timerLabelMilliseconds);
 		co_return timerLabelMilliseconds;
 	}
 
 	sscl::tests::throwIfTimerWaitFailed(waitError);
+	trace.recordTimerCompletionThread(timerLabelMilliseconds);
 	co_return timerLabelMilliseconds;
 }
 
@@ -89,15 +152,19 @@ void throwIfElapsedTooShort(
 
 CallerDriver runGroupTimerRace(
 	std::exception_ptr &exceptionPtr,
-	std::function<void()> completion)
+	std::function<void()> completion,
+	GroupTimerThreadTrace &trace)
 {
 	(void)exceptionPtr;
 	(void)completion;
 
 	sscl::co::Group group;
-	CalleeIntInvoker invokerShort = waitDeadlineTimer(timerDelayShortMs);
-	CalleeIntInvoker invokerMedium = waitDeadlineTimer(timerDelayMediumMs);
-	CalleeIntInvoker invokerLong = waitDeadlineTimer(timerDelayLongMs);
+	CalleeIntInvoker invokerShort =
+		waitDeadlineTimer(timerDelayShortMs, trace);
+	CalleeIntInvoker invokerMedium =
+		waitDeadlineTimer(timerDelayMediumMs, trace);
+	CalleeIntInvoker invokerLong =
+		waitDeadlineTimer(timerDelayLongMs, trace);
 
 	group.add(invokerShort);
 	group.add(invokerMedium);
@@ -107,6 +174,7 @@ CallerDriver runGroupTimerRace(
 
 	auto awaitFirst = group.getAwaitFirstSettlementInvoker();
 	auto [firstSettlement, allSettlementsAfterFirst] = co_await awaitFirst;
+	trace.recordAwaitFirstResumeThread();
 
 	const auto firstElapsedMs =
 		std::chrono::duration_cast<Ms>(Clock::now() - testStart);
@@ -125,6 +193,7 @@ CallerDriver runGroupTimerRace(
 
 	auto awaitAll = group.getAwaitAllSettlementsInvoker();
 	auto &allSettlements = co_await awaitAll;
+	trace.recordAwaitAllResumeThread();
 
 	const auto allElapsedMs =
 		std::chrono::duration_cast<Ms>(Clock::now() - testStart);
@@ -137,16 +206,16 @@ CallerDriver runGroupTimerRace(
 		throw std::runtime_error("expected three settlements");
 	}
 
-	sscl::tests::expectCompletedIntSettlement<CalleeIntInvoker>(
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
 		firstSettlement,
 		timerDelayShortMs);
-	sscl::tests::expectCompletedIntSettlement<CalleeIntInvoker>(
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
 		allSettlementsAfterFirst[0],
 		timerDelayShortMs);
-	sscl::tests::expectCompletedIntSettlement<CalleeIntInvoker>(
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
 		allSettlementsAfterFirst[1],
 		timerDelayMediumMs);
-	sscl::tests::expectCompletedIntSettlement<CalleeIntInvoker>(
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
 		allSettlementsAfterFirst[2],
 		timerDelayLongMs);
 
@@ -156,18 +225,19 @@ CallerDriver runGroupTimerRace(
 CallerDriver runGroupTimerCancelLongAfterAwaitFirst(
 	std::exception_ptr &exceptionPtr,
 	std::function<void()> completion,
-	sscl::tests::CancelableDeadlineTimerRegistry &registry)
+	sscl::tests::CancelableDeadlineTimerRegistry &registry,
+	GroupTimerThreadTrace &trace)
 {
 	(void)exceptionPtr;
 	(void)completion;
 
 	sscl::co::Group group;
 	CalleeIntInvoker invokerShort =
-		waitCancelableDeadlineTimer(timerDelayShortMs, registry);
+		waitCancelableDeadlineTimer(timerDelayShortMs, registry, trace);
 	CalleeIntInvoker invokerMedium =
-		waitCancelableDeadlineTimer(timerDelayMediumMs, registry);
+		waitCancelableDeadlineTimer(timerDelayMediumMs, registry, trace);
 	CalleeIntInvoker invokerLong =
-		waitCancelableDeadlineTimer(timerDelayLongMs, registry);
+		waitCancelableDeadlineTimer(timerDelayLongMs, registry, trace);
 
 	group.add(invokerShort);
 	group.add(invokerMedium);
@@ -177,6 +247,7 @@ CallerDriver runGroupTimerCancelLongAfterAwaitFirst(
 
 	auto awaitFirst = group.getAwaitFirstSettlementInvoker();
 	auto [firstSettlement, allSettlementsAfterFirst] = co_await awaitFirst;
+	trace.recordAwaitFirstResumeThread();
 
 	if (&firstSettlement.invokerAs<CalleeIntInvoker>() != &invokerShort) {
 		throw std::runtime_error("cancel test first settlement mismatch");
@@ -190,6 +261,7 @@ CallerDriver runGroupTimerCancelLongAfterAwaitFirst(
 
 	auto awaitAll = group.getAwaitAllSettlementsInvoker();
 	auto &allSettlements = co_await awaitAll;
+	trace.recordAwaitAllResumeThread();
 
 	const auto allElapsedMs =
 		std::chrono::duration_cast<Ms>(Clock::now() - testStart);
@@ -207,13 +279,13 @@ CallerDriver runGroupTimerCancelLongAfterAwaitFirst(
 		throw std::runtime_error("cancel test expected three settlements");
 	}
 
-	sscl::tests::expectCompletedIntSettlement<CalleeIntInvoker>(
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
 		allSettlements[0],
 		timerDelayShortMs);
-	sscl::tests::expectCompletedIntSettlement<CalleeIntInvoker>(
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
 		allSettlements[1],
 		timerDelayMediumMs);
-	sscl::tests::expectCompletedIntSettlement<CalleeIntInvoker>(
+	sscl::tests::requireCompletedIntSettlement<CalleeIntInvoker>(
 		allSettlements[2],
 		timerDelayLongMs);
 
@@ -229,6 +301,25 @@ class GroupTimerTest
 :	public ::testing::Test
 {
 protected:
+	void assertTimerTraceCrossedThreads(
+		const GroupTimerThreadTrace &trace)
+	{
+		EXPECT_EQ(
+			trace.timerCompletionThread(timerDelayShortMs),
+			threads.callee().osThreadId());
+		EXPECT_EQ(
+			trace.timerCompletionThread(timerDelayMediumMs),
+			threads.callee().osThreadId());
+		EXPECT_EQ(
+			trace.timerCompletionThread(timerDelayLongMs),
+			threads.callee().osThreadId());
+		EXPECT_EQ(trace.awaitFirstThread(), threads.caller().osThreadId());
+		EXPECT_EQ(trace.awaitAllThread(), threads.caller().osThreadId());
+		EXPECT_NE(
+			trace.timerCompletionThread(timerDelayShortMs),
+			trace.awaitFirstThread());
+	}
+
 	sscl::tests::PostingThreadSet threads;
 };
 
@@ -236,33 +327,42 @@ protected:
 
 TEST_F(GroupTimerTest, AwaitFirstReturnsShortestTimerAndAwaitAllWaitsForLongest)
 {
+	GroupTimerThreadTrace trace;
+
 	ASSERT_NO_THROW(
 		sscl::tests::runNonViralPostingTask(
 			threads.caller(),
-			[](
+			[&trace](
 				std::exception_ptr &exceptionPtr,
 				std::function<void()> completion)
 			{
 				return runGroupTimerRace(
 					exceptionPtr,
-					std::move(completion));
+					std::move(completion),
+					trace);
 			}));
+
+	assertTimerTraceCrossedThreads(trace);
 }
 
 TEST_F(GroupTimerTest, CancelLongTimerAfterAwaitFirst)
 {
 	sscl::tests::CancelableDeadlineTimerRegistry registry;
+	GroupTimerThreadTrace trace;
 
 	ASSERT_NO_THROW(
 		sscl::tests::runNonViralPostingTask(
 			threads.caller(),
-			[&registry](
+			[&registry, &trace](
 				std::exception_ptr &exceptionPtr,
 				std::function<void()> completion)
 			{
 				return runGroupTimerCancelLongAfterAwaitFirst(
 					exceptionPtr,
 					std::move(completion),
-					registry);
+					registry,
+					trace);
 			}));
+
+	assertTimerTraceCrossedThreads(trace);
 }

tests/co/viral_non_posting_tests.cpp

@@ -12,7 +12,11 @@
 #include <boost/system/error_code.hpp>
 
 #include <spinscale/co/invokers.h>
+#include <spinscale/co/group.h>
+#include <spinscale/componentThread.h>
 
+#include <support/coroutineDriver.h>
+#include <support/groupAssertions.h>
 #include <support/threadHarness.h>
 #include <support/timerAwaiters.h>
 
@@ -28,6 +32,9 @@ using TestInvoker = sscl::co::ViralNonPostingInvoker<T>;
 
 using TestDriver = TestInvoker<int>;
 using TestVoidDriver = TestInvoker<void>;
+using CallerPostingDriver =
+	sscl::tests::RoleNonViralPostingInvoker<
+		sscl::tests::PostingThreadRole::CALLER>;
 
 struct ThreadIdPair
 {
@@ -101,18 +108,14 @@ protected:
 
 	int runDriver(TestDriver &driver)
 	{
-		sscl::tests::IoContextPump::pumpUntilIdle(ioContext);
-		return finishDriver(driver);
+		return sscl::tests::CoroutineDriver::pumpUntilIdleAndReturnValue(
+			ioContext,
+			driver);
 	}
 
 	int finishDriver(TestDriver &driver)
 	{
-		if (driver.completedReturnValues().myExceptionPtr) {
-			std::rethrow_exception(
-				driver.completedReturnValues().myExceptionPtr);
-		}
-
-		return driver.completedReturnValues().myReturnValue;
+		return sscl::tests::CoroutineDriver::completedReturnValue(driver);
 	}
 
 	boost::asio::io_context ioContext;
@@ -140,6 +143,18 @@ TestVoidDriver voidReturnImmediately()
 	co_return;
 }
 
+TestVoidDriver voidMemberAfterDelay(
+	boost::asio::io_context &ioContext,
+	int delayMilliseconds)
+{
+	const boost::system::error_code waitError =
+		co_await sscl::tests::DeadlineTimerAwaiter{
+			ioContext,
+			delayMilliseconds};
+	sscl::tests::throwIfTimerWaitFailed(waitError);
+	co_return;
+}
+
 TestInvoker<int> throwRuntimeErrorImmediately()
 {
 	throw std::runtime_error(expectedThrowMessage);
@@ -412,6 +427,79 @@ TestDriver testNestedInnerSuspension(boost::asio::io_context &ioContext)
 	co_return 0;
 }
 
+CallerPostingDriver nonPostingVoidMemberInGroupDriver(
+	std::exception_ptr &exceptionPtr,
+	std::function<void()> completion)
+{
+	(void)exceptionPtr;
+	(void)completion;
+
+	sscl::co::Group group;
+	TestVoidDriver voidInvoker = voidMemberAfterDelay(
+		sscl::ComponentThread::getSelf()->getIoContext(),
+		delayShortMs);
+	group.add(voidInvoker);
+
+	auto &allDescriptors = co_await group.getAwaitAllSettlementsInvoker();
+
+	if (allDescriptors.size() != 1) {
+		throw std::runtime_error("voidMemberInGroup count mismatch");
+	}
+
+	sscl::tests::requireCompletedSettlement(allDescriptors[0]);
+
+	co_return;
+}
+
+CallerPostingDriver nonPostingGroupMixedImmediateAndDelayedDriver(
+	std::exception_ptr &exceptionPtr,
+	std::function<void()> completion)
+{
+	(void)exceptionPtr;
+	(void)completion;
+
+	sscl::co::Group group;
+	TestInvoker<int> immediateInvoker = returnLabelImmediately(11);
+	TestInvoker<int> delayedInvoker = waitAndReturnLabel(
+		sscl::ComponentThread::getSelf()->getIoContext(),
+		delayShortMs);
+
+	group.add(immediateInvoker);
+	group.add(delayedInvoker);
+
+	auto &allDescriptors = co_await group.getAwaitAllSettlementsInvoker();
+
+	if (allDescriptors.size() != 2) {
+		throw std::runtime_error("groupMixedImmediateAndDelayed count mismatch");
+	}
+
+	bool sawImmediate = false;
+	bool sawDelayed = false;
+
+	for (auto &descriptor : allDescriptors) {
+		sscl::tests::requireCompletedSettlement(descriptor);
+		const int label = sscl::tests::completedIntValue(
+			descriptor.invokerAs<TestInvoker<int>>());
+		if (label == 11) {
+			sawImmediate = true;
+		}
+		else if (label == delayShortMs) {
+			sawDelayed = true;
+		}
+		else {
+			throw std::runtime_error(
+				"groupMixedImmediateAndDelayed unexpected label");
+		}
+	}
+
+	if (!sawImmediate || !sawDelayed) {
+		throw std::runtime_error(
+			"groupMixedImmediateAndDelayed missing expected label");
+	}
+
+	co_return;
+}
+
 } // namespace
 
 TEST_F(ViralNonPostingTest, ImmediateReturnFastPath)
@@ -509,3 +597,37 @@ TEST_F(ViralNonPostingTest, NestedInnerSuspension)
 	TestDriver driver = testNestedInnerSuspension(ioContext);
 	EXPECT_NO_THROW({ EXPECT_EQ(runDriver(driver), 0); });
 }
+
+TEST(ViralNonPostingGroupIntegrationTest, VoidMemberInGroup)
+{
+	sscl::tests::PostingThreadSet threads;
+
+	ASSERT_NO_THROW(
+		sscl::tests::runNonViralPostingTask(
+			threads.caller(),
+			[](
+				std::exception_ptr &exceptionPtr,
+				std::function<void()> completion)
+			{
+				return nonPostingVoidMemberInGroupDriver(
+					exceptionPtr,
+					std::move(completion));
+			}));
+}
+
+TEST(ViralNonPostingGroupIntegrationTest, MixedImmediateAndDelayedInGroup)
+{
+	sscl::tests::PostingThreadSet threads;
+
+	ASSERT_NO_THROW(
+		sscl::tests::runNonViralPostingTask(
+			threads.caller(),
+			[](
+				std::exception_ptr &exceptionPtr,
+				std::function<void()> completion)
+			{
+				return nonPostingGroupMixedImmediateAndDelayedDriver(
+					exceptionPtr,
+					std::move(completion));
+			}));
+}

tests/support/coroutineDriver.h

@@ -0,0 +1,38 @@
+#ifndef SPINSCALE_TEST_SUPPORT_COROUTINE_DRIVER_H
+#define SPINSCALE_TEST_SUPPORT_COROUTINE_DRIVER_H
+
+#include <exception>
+
+#include <boost/asio/io_context.hpp>
+
+#include <support/threadHarness.h>
+
+namespace sscl::tests {
+
+class CoroutineDriver
+{
+public:
+	template <typename Invoker>
+	static auto completedReturnValue(Invoker &invoker)
+	{
+		if (invoker.completedReturnValues().myExceptionPtr) {
+			std::rethrow_exception(
+				invoker.completedReturnValues().myExceptionPtr);
+		}
+
+		return invoker.completedReturnValues().myReturnValue;
+	}
+
+	template <typename Invoker>
+	static auto pumpUntilIdleAndReturnValue(
+		boost::asio::io_context &ioContext,
+		Invoker &invoker)
+	{
+		IoContextPump::pumpUntilIdle(ioContext);
+		return completedReturnValue(invoker);
+	}
+};
+
+} // namespace sscl::tests
+
+#endif // SPINSCALE_TEST_SUPPORT_COROUTINE_DRIVER_H

tests/support/groupAssertions.h

@@ -2,6 +2,7 @@
 #define SPINSCALE_TEST_SUPPORT_GROUP_ASSERTIONS_H
 
 #include <exception>
+#include <stdexcept>
 #include <string>
 
 #include <gtest/gtest.h>
@@ -21,12 +22,31 @@ int completedIntValue(Invoker &invoker)
 	return invoker.completedReturnValues().myReturnValue;
 }
 
-inline void expectCompletedSettlement(
+inline void requireCompletedSettlement(
 	const sscl::co::Group::SettlementDescriptor &descriptor)
 {
-	EXPECT_EQ(
-		descriptor.type,
-		sscl::co::Group::SettlementDescriptor::TypeE::COMPLETED);
+	if (descriptor.type !=
+		sscl::co::Group::SettlementDescriptor::TypeE::COMPLETED)
+	{
+		throw std::runtime_error("Expected completed settlement");
+	}
+}
+
+template <typename Invoker>
+void requireCompletedIntSettlement(
+	const sscl::co::Group::SettlementDescriptor &descriptor,
+	int expectedValue)
+{
+	requireCompletedSettlement(descriptor);
+
+	const int actualValue = completedIntValue(descriptor.invokerAs<Invoker>());
+	if (actualValue != expectedValue) {
+		throw std::runtime_error(
+			"Expected completed settlement value "
+			+ std::to_string(expectedValue)
+			+ ", got "
+			+ std::to_string(actualValue));
+	}
 }
 
 template <typename Invoker>
@@ -34,39 +54,85 @@ void expectCompletedIntSettlement(
 	const sscl::co::Group::SettlementDescriptor &descriptor,
 	int expectedValue)
 {
-	ASSERT_EQ(
-		descriptor.type,
-		sscl::co::Group::SettlementDescriptor::TypeE::COMPLETED);
-	EXPECT_EQ(completedIntValue(descriptor.invokerAs<Invoker>()), expectedValue);
+	EXPECT_NO_THROW(
+		requireCompletedIntSettlement<Invoker>(
+			descriptor,
+			expectedValue));
+}
+
+inline void expectCompletedSettlement(
+	const sscl::co::Group::SettlementDescriptor &descriptor)
+{
+	EXPECT_NO_THROW(requireCompletedSettlement(descriptor));
+}
+
+inline void requireExceptionSettlement(
+	const sscl::co::Group::SettlementDescriptor &descriptor)
+{
+	if (descriptor.type !=
+		sscl::co::Group::SettlementDescriptor::TypeE::EXCEPTION_THROWN)
+	{
+		throw std::runtime_error("Expected exception settlement");
+	}
+
+	if (!descriptor.calleeException) {
+		throw std::runtime_error("Expected exception pointer in settlement");
+	}
 }
 
 inline void expectExceptionSettlement(
 	const sscl::co::Group::SettlementDescriptor &descriptor)
 {
-	EXPECT_EQ(
-		descriptor.type,
-		sscl::co::Group::SettlementDescriptor::TypeE::EXCEPTION_THROWN);
-	EXPECT_TRUE(descriptor.calleeException != nullptr);
+	EXPECT_NO_THROW(requireExceptionSettlement(descriptor));
 }
 
-inline void expectRuntimeErrorSettlement(
+inline void requireRuntimeErrorSettlement(
 	const sscl::co::Group::SettlementDescriptor &descriptor,
 	const std::string &expectedMessage)
 {
-	ASSERT_EQ(
-		descriptor.type,
-		sscl::co::Group::SettlementDescriptor::TypeE::EXCEPTION_THROWN);
-	ASSERT_TRUE(descriptor.calleeException != nullptr);
+	requireExceptionSettlement(descriptor);
 
 	try {
 		std::rethrow_exception(descriptor.calleeException);
 	}
 	catch (const std::runtime_error &runtimeError) {
-		EXPECT_EQ(std::string(runtimeError.what()), expectedMessage);
+		const std::string actualMessage = runtimeError.what();
+		if (actualMessage != expectedMessage) {
+			throw std::runtime_error(
+				"Expected runtime_error settlement message \""
+				+ expectedMessage
+				+ "\", got \""
+				+ actualMessage
+				+ "\"");
+		}
 		return;
 	}
 	catch (...) {
-		FAIL() << "Expected std::runtime_error settlement.";
+		throw std::runtime_error("Expected std::runtime_error settlement");
+	}
+}
+
+inline void requireIntExceptionSettlement(
+	const sscl::co::Group::SettlementDescriptor &descriptor,
+	int expectedValue)
+{
+	requireExceptionSettlement(descriptor);
+
+	try {
+		std::rethrow_exception(descriptor.calleeException);
+	}
+	catch (int caughtValue) {
+		if (caughtValue != expectedValue) {
+			throw std::runtime_error(
+				"Expected int exception settlement value "
+				+ std::to_string(expectedValue)
+				+ ", got "
+				+ std::to_string(caughtValue));
+		}
+		return;
+	}
+	catch (...) {
+		throw std::runtime_error("Expected int exception settlement");
 	}
 }
 
@@ -74,29 +140,36 @@ inline void expectIntExceptionSettlement(
 	const sscl::co::Group::SettlementDescriptor &descriptor,
 	int expectedValue)
 {
-	ASSERT_EQ(
-		descriptor.type,
-		sscl::co::Group::SettlementDescriptor::TypeE::EXCEPTION_THROWN);
-	ASSERT_TRUE(descriptor.calleeException != nullptr);
+	EXPECT_NO_THROW(
+		requireIntExceptionSettlement(
+			descriptor,
+			expectedValue));
+}
 
-	try {
-		std::rethrow_exception(descriptor.calleeException);
+inline void expectRuntimeErrorSettlement(
+	const sscl::co::Group::SettlementDescriptor &descriptor,
+	const std::string &expectedMessage)
+{
+	EXPECT_NO_THROW(
+		requireRuntimeErrorSettlement(
+			descriptor,
+			expectedMessage));
 }
-	catch (int caughtValue) {
-		EXPECT_EQ(caughtValue, expectedValue);
-		return;
-	}
-	catch (...) {
-		FAIL() << "Expected int exception settlement.";
+
+inline void requireEmptyGroupError(
+	const std::runtime_error &runtimeError)
+{
+	constexpr const char *expectedMessage =
+		"co_await: Group has no member invokers; call add() before awaiting";
+	if (std::string(runtimeError.what()) != expectedMessage) {
+		throw std::runtime_error("Unexpected empty group error message");
 	}
 }
 
 inline void expectEmptyGroupError(
 	const std::runtime_error &runtimeError)
 {
-	constexpr const char *expectedMessage =
-		"co_await: Group has no member invokers; call add() before awaiting";
-	EXPECT_EQ(std::string(runtimeError.what()), expectedMessage);
+	EXPECT_NO_THROW(requireEmptyGroupError(runtimeError));
 }
 
 } // namespace sscl::tests

tests/support/threadHarness.cpp

@@ -217,13 +217,32 @@ void ThreadRegistry::registerThread(
 	DedicatedIoThread &thread)
 {
 	std::lock_guard<std::mutex> guard(registryMutex());
-	threadsByRole()[role] = &thread;
+	auto [iterator, inserted] = threadsByRole().emplace(role, &thread);
+
+	if (!inserted) {
+		throw std::runtime_error(
+			"Test thread role already registered for " + threadRoleName(role));
+	}
 }
 
-void ThreadRegistry::unregisterThread(PostingThreadRole role)
+void ThreadRegistry::unregisterThread(
+	PostingThreadRole role,
+	DedicatedIoThread &expectedThread)
 {
 	std::lock_guard<std::mutex> guard(registryMutex());
-	threadsByRole().erase(role);
+	auto iterator = threadsByRole().find(role);
+
+	if (iterator == threadsByRole().end()) {
+		return;
+	}
+
+	if (iterator->second != &expectedThread) {
+		throw std::runtime_error(
+			"Test thread role registered to a different thread for "
+			+ threadRoleName(role));
+	}
+
+	threadsByRole().erase(iterator);
 }
 
 boost::asio::io_context &ThreadRegistry::ioContext(PostingThreadRole role)
@@ -272,6 +291,20 @@ PostingThreadSet::PostingThreadSet()
 	bodyThread(PostingThreadRole::BODY),
 	worldThread(PostingThreadRole::WORLD),
 	legThread(PostingThreadRole::LEG)
+{
+	previousPuppeteerThread = sscl::ComponentThread::getPptr();
+	previousPuppeteerThreadId = sscl::pptr::puppeteerThreadId;
+	registerAllThreads();
+	installCallerAsPuppeteer();
+}
+
+PostingThreadSet::~PostingThreadSet()
+{
+	restorePreviousPuppeteer();
+	unregisterAllThreads();
+}
+
+void PostingThreadSet::registerAllThreads()
 {
 	ThreadRegistry::registerThread(PostingThreadRole::CALLER, callerThread);
 	ThreadRegistry::registerThread(PostingThreadRole::CALLEE, calleeThread);
@@ -279,22 +312,31 @@ PostingThreadSet::PostingThreadSet()
 	ThreadRegistry::registerThread(PostingThreadRole::BODY, bodyThread);
 	ThreadRegistry::registerThread(PostingThreadRole::WORLD, worldThread);
 	ThreadRegistry::registerThread(PostingThreadRole::LEG, legThread);
+}
 
+void PostingThreadSet::unregisterAllThreads()
+{
+	ThreadRegistry::unregisterThread(PostingThreadRole::CALLER, callerThread);
+	ThreadRegistry::unregisterThread(PostingThreadRole::CALLEE, calleeThread);
+	ThreadRegistry::unregisterThread(
+		PostingThreadRole::ALTERNATE,
+		alternateThread);
+	ThreadRegistry::unregisterThread(PostingThreadRole::BODY, bodyThread);
+	ThreadRegistry::unregisterThread(PostingThreadRole::WORLD, worldThread);
+	ThreadRegistry::unregisterThread(PostingThreadRole::LEG, legThread);
+}
+
+void PostingThreadSet::installCallerAsPuppeteer()
+{
 	sscl::ComponentThread::setPuppeteerThreadId(
 		static_cast<sscl::ThreadId>(PostingThreadRole::CALLER));
 	sscl::ComponentThread::setPuppeteerThread(callerThread.componentThread());
 }
 
-PostingThreadSet::~PostingThreadSet()
+void PostingThreadSet::restorePreviousPuppeteer()
 {
-	ThreadRegistry::unregisterThread(PostingThreadRole::CALLER);
-	ThreadRegistry::unregisterThread(PostingThreadRole::CALLEE);
-	ThreadRegistry::unregisterThread(PostingThreadRole::ALTERNATE);
-	ThreadRegistry::unregisterThread(PostingThreadRole::BODY);
-	ThreadRegistry::unregisterThread(PostingThreadRole::WORLD);
-	ThreadRegistry::unregisterThread(PostingThreadRole::LEG);
-
-	sscl::ComponentThread::setPuppeteerThread(nullptr);
+	sscl::ComponentThread::setPuppeteerThreadId(previousPuppeteerThreadId);
+	sscl::ComponentThread::setPuppeteerThread(previousPuppeteerThread);
 }
 
 DedicatedIoThread &PostingThreadSet::thread(PostingThreadRole role)

tests/support/threadHarness.h

@@ -180,7 +180,9 @@ public:
 	static void registerThread(
 		PostingThreadRole role,
 		DedicatedIoThread &thread);
-	static void unregisterThread(PostingThreadRole role);
+	static void unregisterThread(
+		PostingThreadRole role,
+		DedicatedIoThread &expectedThread);
 	static boost::asio::io_context &ioContext(PostingThreadRole role);
 	static std::thread::id osThreadId(PostingThreadRole role);
 
@@ -240,14 +242,28 @@ public:
 	DedicatedIoThread &leg();
 
 private:
+	void registerAllThreads();
+	void unregisterAllThreads();
+	void installCallerAsPuppeteer();
+	void restorePreviousPuppeteer();
+
 	DedicatedIoThread callerThread;
 	DedicatedIoThread calleeThread;
 	DedicatedIoThread alternateThread;
 	DedicatedIoThread bodyThread;
 	DedicatedIoThread worldThread;
 	DedicatedIoThread legThread;
+	std::shared_ptr<sscl::PuppeteerThread> previousPuppeteerThread;
+	sscl::ThreadId previousPuppeteerThreadId = 0;
 };
 
+template <typename Function>
+auto RunOnThread(DedicatedIoThread &thread, Function &&function)
+	-> std::invoke_result_t<Function &>
+{
+	return thread.runSync(std::forward<Function>(function));
+}
+
 class CrossThreadTrace
 {
 public: