diff --git a/.gitmodules b/.gitmodules
new file mode 100644
index 0000000..8cf8b5e
--- /dev/null
+++ b/.gitmodules
@@ -0,0 +1,3 @@
+[submodule "googletest"]
+	path = googletest
+	url = https://github.com/google/googletest.git
diff --git a/CMakeLists.txt b/CMakeLists.txt
index 3f2f847..6e502e9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,8 @@
 cmake_minimum_required(VERSION 3.16)
 project(libspinscale VERSION 0.1.0 LANGUAGES CXX)
 
+include(GNUInstallDirs)
+
 # Set C++ standard
 set(CMAKE_CXX_STANDARD 20)
 set(CMAKE_CXX_STANDARD_REQUIRED ON)
@@ -148,16 +150,29 @@ install(DIRECTORY include/spinscale
 	FILES_MATCHING PATTERN "*.h"
 )
 
-if(BUILD_TESTING AND TARGET GTest::gtest_main)
-	add_executable(spinscale_env_kv_store_tests
-		tests/env_kv_store_test.cpp
-	)
-	target_link_libraries(spinscale_env_kv_store_tests PRIVATE
-		spinscale
-		GTest::gtest_main
-	)
-	include(GoogleTest)
-	gtest_discover_tests(spinscale_env_kv_store_tests)
+if(CMAKE_SOURCE_DIR STREQUAL CMAKE_CURRENT_SOURCE_DIR)
+	set(_libspinscaleTestsDefault ON)
+else()
+	set(_libspinscaleTestsDefault OFF)
+	if(DEFINED ENABLE_TESTS AND ENABLE_TESTS)
+		set(_libspinscaleTestsDefault ON)
+	endif()
+endif()
+
+option(LIBSPINSCALE_BUILD_TESTS "Build libspinscale unit tests"
+	${_libspinscaleTestsDefault})
+
+if(LIBSPINSCALE_BUILD_TESTS)
+	if(NOT TARGET gtest AND NOT TARGET gtest_main)
+		set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+		add_subdirectory(
+			${CMAKE_CURRENT_SOURCE_DIR}/googletest
+			${CMAKE_CURRENT_BINARY_DIR}/googletest
+			EXCLUDE_FROM_ALL)
+	endif()
+
+	enable_testing()
+	add_subdirectory(tests)
 endif()
 
 install(FILES include/boostAsioLinkageFix.h
diff --git a/googletest b/googletest
new file mode 160000
index 0000000..7140cd4
--- /dev/null
+++ b/googletest
@@ -0,0 +1 @@
+Subproject commit 7140cd416cecd7462a8aae488024abeee55598e4
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
new file mode 100644
index 0000000..bfeeccf
--- /dev/null
+++ b/tests/CMakeLists.txt
@@ -0,0 +1,37 @@
+add_executable(spinscale_env_kv_store_tests
+	env_kv_store_test.cpp
+)
+
+target_link_libraries(spinscale_env_kv_store_tests PRIVATE
+	spinscale
+	gtest_main
+)
+
+add_dependencies(spinscale_env_kv_store_tests gtest_main)
+add_test(NAME spinscale_env_kv_store_tests
+	COMMAND spinscale_env_kv_store_tests)
+
+add_executable(qutex_tests
+	cps/qutex_tests.cpp
+)
+
+target_link_libraries(qutex_tests PRIVATE
+	spinscale
+	gtest_main
+)
+
+add_dependencies(qutex_tests gtest_main)
+add_test(NAME qutex_tests COMMAND qutex_tests)
+
+add_executable(nonViralTaskNursery_tests
+	co/nonViralTaskNursery_tests.cpp
+)
+
+target_link_libraries(nonViralTaskNursery_tests PRIVATE
+	spinscale
+	gtest_main
+)
+
+add_dependencies(nonViralTaskNursery_tests gtest_main)
+add_test(NAME nonViralTaskNursery_tests
+	COMMAND nonViralTaskNursery_tests)
diff --git a/tests/co/nonViralTaskNursery_tests.cpp b/tests/co/nonViralTaskNursery_tests.cpp
new file mode 100644
index 0000000..4fdf7bb
--- /dev/null
+++ b/tests/co/nonViralTaskNursery_tests.cpp
@@ -0,0 +1,657 @@
+#include <atomic>
+#include <chrono>
+#include <coroutine>
+#include <exception>
+#include <functional>
+#include <gtest/gtest.h>
+#include <thread>
+
+#include <boost/asio/io_context.hpp>
+#include <boost/asio/post.hpp>
+
+#include <spinscale/co/invokers.h>
+#include <spinscale/co/nonViralTaskNursery.h>
+#include <spinscale/syncCancelerForAsyncWork.h>
+
+namespace {
+
+struct ResumeGate
+{
+	std::coroutine_handle<> waitingHandle;
+
+	bool await_ready() const noexcept
+		{ return false; }
+
+	bool await_suspend(std::coroutine_handle<> callerHandle) noexcept
+	{
+		waitingHandle = callerHandle;
+		return true;
+	}
+
+	void await_resume() const noexcept
+		{}
+};
+
+sscl::co::NonViralNonPostingInvoker immediateCompleteCReq(
+	std::exception_ptr &exceptionPtr,
+	std::function<void()> completion)
+{
+	(void)exceptionPtr;
+	(void)completion;
+	co_return;
+}
+
+sscl::co::NonViralNonPostingInvoker throwingCompleteCReq(
+	std::exception_ptr &exceptionPtr,
+	std::function<void()> completion)
+{
+	(void)exceptionPtr;
+	(void)completion;
+	throw std::runtime_error("nursery test failure");
+	co_return;
+}
+
+sscl::co::NonViralNonPostingInvoker suspendUntilResumeCReq(
+	std::exception_ptr &exceptionPtr,
+	std::function<void()> completion,
+	ResumeGate &gate)
+{
+	(void)exceptionPtr;
+	(void)completion;
+	co_await gate;
+	co_return;
+}
+
+sscl::co::NonViralNonPostingInvoker cancelAwareSuspendCReq(
+	std::exception_ptr &exceptionPtr,
+	std::function<void()> completion,
+	sscl::SyncCancelerForAsyncWork &canceler,
+	ResumeGate &gate)
+{
+	(void)exceptionPtr;
+	(void)completion;
+
+	while (!canceler.isCancellationRequested())
+	{
+		co_await gate;
+	}
+
+	co_return;
+}
+
+} // namespace
+
+class NonViralTaskNurseryTest : public ::testing::Test
+{
+protected:
+	void SetUp() override
+	{
+		nursery.openAdmission();
+	}
+
+	sscl::co::NonViralTaskNursery nursery;
+	ResumeGate gate;
+	ResumeGate gate2;
+};
+
+TEST_F(NonViralTaskNurseryTest, GetNewSlotLeaseFillCommitRetires)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&lease]()
+		{
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda());
+		});
+	lease.commit();
+
+	EXPECT_TRUE(nursery.allSettled());
+	EXPECT_EQ(nursery.unsettledCount(), 0U);
+}
+
+TEST_F(NonViralTaskNurseryTest, UncommittedLeaseReleasesReservation)
+{
+	EXPECT_EQ(nursery.unsettledCount(), 0U);
+	{
+		auto lease = nursery.getNewSlotLease();
+		(void)lease;
+	}
+
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, CloseAdmissionRejectsNewLeases)
+{
+	nursery.closeAdmission();
+
+	EXPECT_THROW(nursery.getNewSlotLease(), std::runtime_error);
+}
+
+TEST_F(NonViralTaskNurseryTest, SetOnSettledHookRejectsAfterFillSlot)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&lease]()
+		{
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda());
+		});
+
+	EXPECT_THROW(
+		lease.setOnSettledHook([](std::exception_ptr &) {}),
+		std::runtime_error);
+	lease.commit();
+}
+
+TEST_F(NonViralTaskNurseryTest, AsyncAwaitFiresOnDrain)
+{
+	std::atomic<bool> drained{false};
+
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&lease]()
+		{
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda());
+		});
+	lease.commit();
+
+	nursery.closeAdmission();
+	nursery.asyncAwaitAllSettlements(
+		[&drained]()
+		{
+			drained.store(true, std::memory_order_release);
+		});
+
+	EXPECT_TRUE(drained.load(std::memory_order_acquire));
+}
+
+TEST_F(NonViralTaskNurseryTest, AsyncAwaitRejectsWhenAdmissionOpen)
+{
+	EXPECT_THROW(nursery.asyncAwaitAllSettlements([]() {}), std::runtime_error);
+}
+
+TEST_F(NonViralTaskNurseryTest, SecondDrainWaiterThrows)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&lease, this]()
+		{
+			return suspendUntilResumeCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda(),
+				gate);
+		});
+	lease.commit();
+
+	nursery.closeAdmission();
+
+	bool firstWaiterRegistered = false;
+	nursery.asyncAwaitAllSettlements(
+		[&firstWaiterRegistered]()
+		{
+			firstWaiterRegistered = true;
+		});
+
+	EXPECT_FALSE(firstWaiterRegistered);
+	EXPECT_THROW(
+		nursery.asyncAwaitAllSettlements([]() {}),
+		std::runtime_error);
+
+	if (gate.waitingHandle)
+	{
+		gate.waitingHandle.resume();
+	}
+}
+
+TEST_F(NonViralTaskNurseryTest, SyncAwaitNestedRun)
+{
+	boost::asio::io_context ioContext;
+
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&lease, this]()
+		{
+			return suspendUntilResumeCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda(),
+				gate);
+		});
+	lease.commit();
+
+	std::thread awaitThread(
+		[this, &ioContext]()
+		{
+			nursery.closeAdmission();
+			nursery.syncAwaitAllSettlements(ioContext);
+		});
+
+	std::this_thread::sleep_for(std::chrono::milliseconds(10));
+
+	ASSERT_TRUE(static_cast<bool>(gate.waitingHandle));
+	gate.waitingHandle.resume();
+
+	awaitThread.join();
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, RequestCancelOnAllDoesNotDestroyInvokers)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.getSyncCanceler().startAcceptingWork();
+	lease.fillSlot(
+		[&lease, this]()
+		{
+			return suspendUntilResumeCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda(),
+				gate);
+		});
+	lease.commit();
+
+	EXPECT_EQ(nursery.unsettledCount(), 1U);
+	nursery.requestCancelOnAll();
+	EXPECT_EQ(nursery.unsettledCount(), 1U);
+
+	ASSERT_TRUE(static_cast<bool>(gate.waitingHandle));
+	gate.waitingHandle.resume();
+
+	std::this_thread::sleep_for(std::chrono::milliseconds(10));
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, RequestCancelOnAllStopsCanceler)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.getSyncCanceler().startAcceptingWork();
+	lease.fillSlot(
+		[&lease, this]()
+		{
+			return cancelAwareSuspendCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda(),
+				lease.getSyncCanceler(),
+				gate);
+		});
+	lease.commit();
+
+	nursery.requestCancelOnAll();
+	EXPECT_TRUE(lease.getSyncCanceler().isCancellationRequested());
+
+	ASSERT_TRUE(static_cast<bool>(gate.waitingHandle));
+	gate.waitingHandle.resume();
+
+	std::this_thread::sleep_for(std::chrono::milliseconds(10));
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, ExceptionPtrRecorded)
+{
+	std::exception_ptr captured;
+
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&captured, &lease]()
+		{
+			std::exception_ptr &exceptionStorage =
+				lease.getExceptionStorage();
+			auto invoker = throwingCompleteCReq(
+				exceptionStorage,
+				lease.getCallerLambda());
+			captured = exceptionStorage;
+			return invoker;
+		});
+	lease.commit();
+
+	EXPECT_TRUE(captured != nullptr);
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, LaunchSugar)
+{
+	auto handle = nursery.launch(
+		[](sscl::co::NonViralTaskNursery::Slot::Lease &lease)
+		{
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda());
+		});
+
+	EXPECT_TRUE(handle == handle);
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, LaunchWithOnSettledHook)
+{
+	std::atomic<bool> hookRan{false};
+
+	nursery.launch(
+		[](sscl::co::NonViralTaskNursery::Slot::Lease &lease)
+		{
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda());
+		},
+		[&hookRan](std::exception_ptr &)
+		{
+			hookRan.store(true, std::memory_order_release);
+		});
+
+	EXPECT_TRUE(hookRan.load(std::memory_order_acquire));
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, HandleStability)
+{
+	auto handle = nursery.launch(
+		[](sscl::co::NonViralTaskNursery::Slot::Lease &lease)
+		{
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda());
+		});
+
+	sscl::co::NonViralTaskNursery::Slot::Handle copy = handle;
+	EXPECT_TRUE(handle == copy);
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, CommitWithoutFillSlotThrows)
+{
+	auto lease = nursery.getNewSlotLease();
+
+	EXPECT_THROW(lease.commit(), std::runtime_error);
+}
+
+TEST_F(NonViralTaskNurseryTest, DoubleCommitThrows)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&lease]()
+		{
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda());
+		});
+	lease.commit();
+
+	EXPECT_THROW(lease.commit(), std::runtime_error);
+}
+
+TEST_F(NonViralTaskNurseryTest, FillSlotTwiceThrows)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&lease, this]()
+		{
+			return suspendUntilResumeCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda(),
+				gate);
+		});
+
+	EXPECT_THROW(
+		lease.fillSlot(
+			[&lease]()
+			{
+				return immediateCompleteCReq(
+					lease.getExceptionStorage(),
+					lease.getCallerLambda());
+			}),
+		std::runtime_error);
+
+	if (gate.waitingHandle) {
+		gate.waitingHandle.resume();
+	}
+
+	lease.commit();
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, SyncAwaitRejectsWhenAdmissionOpen)
+{
+	boost::asio::io_context ioContext;
+
+	EXPECT_THROW(
+		nursery.syncAwaitAllSettlements(ioContext),
+		std::runtime_error);
+}
+
+TEST_F(NonViralTaskNurseryTest, SyncAwaitRejectsStoppedIoContext)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&lease, this]()
+		{
+			return suspendUntilResumeCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda(),
+				gate);
+		});
+	lease.commit();
+
+	nursery.closeAdmission();
+
+	boost::asio::io_context ioContext;
+	ioContext.stop();
+
+	EXPECT_THROW(
+		nursery.syncAwaitAllSettlements(ioContext),
+		std::runtime_error);
+
+	if (gate.waitingHandle) {
+		gate.waitingHandle.resume();
+	}
+}
+
+TEST_F(NonViralTaskNurseryTest, SyncAwaitReturnsImmediatelyWhenDrained)
+{
+	boost::asio::io_context ioContext;
+
+	nursery.closeAdmission();
+	EXPECT_TRUE(nursery.allSettled());
+
+	nursery.syncAwaitAllSettlements(ioContext);
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, UnsettledCountTracksInFlightTasks)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&lease, this]()
+		{
+			return suspendUntilResumeCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda(),
+				gate);
+		});
+	lease.commit();
+
+	EXPECT_EQ(nursery.unsettledCount(), 1U);
+	EXPECT_FALSE(nursery.allSettled());
+
+	if (gate.waitingHandle) {
+		gate.waitingHandle.resume();
+	}
+
+	std::this_thread::sleep_for(std::chrono::milliseconds(10));
+	EXPECT_EQ(nursery.unsettledCount(), 0U);
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, MultipleTasksDrainTogether)
+{
+	std::atomic<bool> drained{false};
+
+	auto lease1 = nursery.getNewSlotLease();
+	lease1.fillSlot(
+		[&lease1, this]()
+		{
+			return suspendUntilResumeCReq(
+				lease1.getExceptionStorage(),
+				lease1.getCallerLambda(),
+				gate);
+		});
+	lease1.commit();
+
+	auto lease2 = nursery.getNewSlotLease();
+	lease2.fillSlot(
+		[&lease2, this]()
+		{
+			return suspendUntilResumeCReq(
+				lease2.getExceptionStorage(),
+				lease2.getCallerLambda(),
+				gate2);
+		});
+	lease2.commit();
+
+	EXPECT_EQ(nursery.unsettledCount(), 2U);
+
+	nursery.closeAdmission();
+	nursery.asyncAwaitAllSettlements(
+		[&drained]()
+		{
+			drained.store(true, std::memory_order_release);
+		});
+
+	EXPECT_FALSE(drained.load(std::memory_order_acquire));
+
+	if (gate.waitingHandle) {
+		gate.waitingHandle.resume();
+	}
+
+	std::this_thread::sleep_for(std::chrono::milliseconds(10));
+	EXPECT_FALSE(drained.load(std::memory_order_acquire));
+
+	if (gate2.waitingHandle) {
+		gate2.waitingHandle.resume();
+	}
+
+	std::this_thread::sleep_for(std::chrono::milliseconds(10));
+	EXPECT_TRUE(drained.load(std::memory_order_acquire));
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, OnSettledHookRunsAtRetirement)
+{
+	std::atomic<bool> hookRan{false};
+
+	auto lease = nursery.getNewSlotLease();
+	lease.setOnSettledHook(
+		[&hookRan](std::exception_ptr &)
+		{
+			hookRan.store(true, std::memory_order_release);
+		});
+	lease.fillSlot(
+		[&lease]()
+		{
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda());
+		});
+	lease.commit();
+
+	EXPECT_TRUE(hookRan.load(std::memory_order_acquire));
+}
+
+TEST_F(NonViralTaskNurseryTest, OnSettledHookSeesRetiredSlot)
+{
+	auto lease = nursery.getNewSlotLease();
+	lease.setOnSettledHook(
+		[this](std::exception_ptr &)
+		{
+			EXPECT_TRUE(nursery.allSettled());
+			EXPECT_EQ(nursery.unsettledCount(), 0U);
+		});
+	lease.fillSlot(
+		[&lease]()
+		{
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda());
+		});
+	lease.commit();
+}
+
+TEST_F(NonViralTaskNurseryTest, DuplicateRetireThrows)
+{
+	std::function<void()> completion;
+
+	auto lease = nursery.getNewSlotLease();
+	lease.fillSlot(
+		[&completion, &lease]()
+		{
+			completion = lease.getCallerLambda();
+			return immediateCompleteCReq(
+				lease.getExceptionStorage(),
+				completion);
+		});
+	lease.commit();
+
+	ASSERT_TRUE(static_cast<bool>(completion));
+	EXPECT_THROW(completion(), std::runtime_error);
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, MovedLeaseTransfersReleaseObligation)
+{
+	EXPECT_EQ(nursery.unsettledCount(), 0U);
+	{
+		auto lease = nursery.getNewSlotLease();
+		auto movedLease = std::move(lease);
+		(void)movedLease;
+	}
+
+	EXPECT_TRUE(nursery.allSettled());
+	EXPECT_EQ(nursery.unsettledCount(), 0U);
+}
+
+TEST_F(NonViralTaskNurseryTest, LaunchAssignsDistinctHandles)
+{
+	auto handle1 = nursery.launch(
+		[this](sscl::co::NonViralTaskNursery::Slot::Lease &lease)
+		{
+			return suspendUntilResumeCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda(),
+				gate);
+		});
+
+	auto handle2 = nursery.launch(
+		[this](sscl::co::NonViralTaskNursery::Slot::Lease &lease)
+		{
+			return suspendUntilResumeCReq(
+				lease.getExceptionStorage(),
+				lease.getCallerLambda(),
+				gate2);
+		});
+
+	EXPECT_NE(handle1, handle2);
+	EXPECT_EQ(nursery.unsettledCount(), 2U);
+
+	if (gate.waitingHandle) {
+		gate.waitingHandle.resume();
+	}
+
+	if (gate2.waitingHandle) {
+		gate2.waitingHandle.resume();
+	}
+
+	std::this_thread::sleep_for(std::chrono::milliseconds(10));
+	EXPECT_TRUE(nursery.allSettled());
+}
+
+TEST_F(NonViralTaskNurseryTest, AdmissionIsOpenReflectsCloseAndOpen)
+{
+	EXPECT_TRUE(nursery.admissionIsOpen());
+
+	nursery.closeAdmission();
+	EXPECT_FALSE(nursery.admissionIsOpen());
+
+	nursery.openAdmission();
+	EXPECT_TRUE(nursery.admissionIsOpen());
+}
diff --git a/tests/cps/qutex_tests.cpp b/tests/cps/qutex_tests.cpp
new file mode 100644
index 0000000..bf33a01
--- /dev/null
+++ b/tests/cps/qutex_tests.cpp
@@ -0,0 +1,373 @@
+#include <gtest/gtest.h>
+#include <spinscale/cps/qutex.h>
+#include <spinscale/cps/lockerAndInvokerBase.h>
+#include <memory>
+#include <stdexcept>
+#include <thread>
+#include <chrono>
+#include <vector>
+
+namespace smo {
+
+// Mock implementation of LockerAndInvokerBase for testing
+class MockLockerAndInvoker : public sscl::cps::LockerAndInvokerBase {
+public:
+    explicit MockLockerAndInvoker(const void* addr)
+        : sscl::cps::LockerAndInvokerBase(addr), awakened(false) {}
+
+    bool awakened;
+    mutable sscl::cps::Qutex* registeredQutex = nullptr;
+    mutable sscl::cps::LockerAndInvokerBase::List::iterator queueIterator;
+
+    sscl::cps::LockerAndInvokerBase::List::iterator
+    getLockvokerIteratorForQutex(sscl::cps::Qutex& qutex) const override
+    {
+        registeredQutex = &qutex;
+
+        for (auto it = qutex.queue.begin(); it != qutex.queue.end(); ++it)
+        {
+            if ((**it) == *this)
+            {
+                queueIterator = it;
+                return it;
+            }
+        }
+
+        throw std::runtime_error(
+            "MockLockerAndInvoker: not registered in qutex queue");
+    }
+
+    void awaken(bool forceAwaken = false) override
+    {
+        (void)forceAwaken;
+        awakened = true;
+    }
+
+    size_t getLockSetSize() const override
+    {
+        return 1;
+    }
+
+    sscl::cps::Qutex& getLockAt(size_t index) const override
+    {
+        if (index != 0 || registeredQutex == nullptr)
+        {
+            throw std::runtime_error(
+                "MockLockerAndInvoker: invalid lock index or no registered qutex");
+        }
+
+        return *registeredQutex;
+    }
+};
+
+class QutexTest : public ::testing::Test {
+protected:
+    void SetUp() override {
+        // Create mock lockvokers with unique addresses
+        mock1 = std::make_shared<MockLockerAndInvoker>(&addr1);
+        mock2 = std::make_shared<MockLockerAndInvoker>(&addr2);
+        mock3 = std::make_shared<MockLockerAndInvoker>(&addr3);
+        mock4 = std::make_shared<MockLockerAndInvoker>(&addr4);
+        mock5 = std::make_shared<MockLockerAndInvoker>(&addr5);
+    }
+
+    void TearDown() override {
+        // Clean up
+    }
+
+    sscl::cps::Qutex qutex{"test-qutex"};
+    std::shared_ptr<MockLockerAndInvoker> mock1, mock2, mock3, mock4, mock5;
+
+    // Unique addresses for testing
+    int addr1 = 1;
+    int addr2 = 2;
+    int addr3 = 3;
+    int addr4 = 4;
+    int addr5 = 5;
+};
+
+// Test basic queue registration and unregistration
+TEST_F(QutexTest, QueueRegistrationAndUnregistration) {
+    // Register mock1 in queue
+    auto it1 = qutex.registerInQueue(mock1);
+    EXPECT_EQ(qutex.queue.size(), 1);
+    EXPECT_FALSE(qutex.isOwned);
+
+    // Register mock2 in queue
+    auto it2 = qutex.registerInQueue(mock2);
+    EXPECT_EQ(qutex.queue.size(), 2);
+
+    // Unregister mock1
+    qutex.unregisterFromQueue(it1);
+    EXPECT_EQ(qutex.queue.size(), 1);
+
+    // Unregister mock2
+    qutex.unregisterFromQueue(it2);
+    EXPECT_EQ(qutex.queue.size(), 0);
+}
+
+// Test single lock acquisition when queue is empty
+TEST_F(QutexTest, SingleLockAcquisitionEmptyQueue) {
+    // Register mock1
+    (void)qutex.registerInQueue(mock1);
+
+    // Try to acquire with nRequiredLocks = 1
+    bool acquired = qutex.tryAcquire(*mock1, 1);
+    EXPECT_TRUE(acquired);
+    EXPECT_TRUE(qutex.isOwned);
+}
+
+// Test single lock acquisition when at front of queue
+TEST_F(QutexTest, SingleLockAcquisitionAtFront) {
+    // Register multiple lockvokers
+    (void)qutex.registerInQueue(mock1);
+    (void)qutex.registerInQueue(mock2);
+    (void)qutex.registerInQueue(mock3);
+
+    // mock1 should be at front, mock3 at back
+    EXPECT_EQ(qutex.queue.front().get(), mock1.get());
+    EXPECT_EQ(qutex.queue.back().get(), mock3.get());
+
+    // mock1 (at front) should succeed
+    bool acquired = qutex.tryAcquire(*mock1, 1);
+    EXPECT_TRUE(acquired);
+    EXPECT_TRUE(qutex.isOwned);
+
+    // mock2 (not at front) should fail
+    qutex.isOwned = false; // Reset for testing
+    bool acquired2 = qutex.tryAcquire(*mock2, 1);
+    EXPECT_FALSE(acquired2);
+}
+
+// Test single lock acquisition failure when not at front
+TEST_F(QutexTest, SingleLockAcquisitionNotAtFront) {
+    // Register multiple lockvokers
+    (void)qutex.registerInQueue(mock1);
+    (void)qutex.registerInQueue(mock2);
+
+    // mock2 (not at front) should fail
+    bool acquired = qutex.tryAcquire(*mock2, 1);
+    EXPECT_FALSE(acquired);
+    EXPECT_FALSE(qutex.isOwned);
+}
+
+// Test multi-lock acquisition (nRequiredLocks > 1)
+TEST_F(QutexTest, MultiLockAcquisition) {
+    // Register 4 lockvokers
+    (void)qutex.registerInQueue(mock1);
+    (void)qutex.registerInQueue(mock2);
+    (void)qutex.registerInQueue(mock3);
+    (void)qutex.registerInQueue(mock4);
+
+    // For nRequiredLocks = 2, need to be in top 50% (top 2 out of 4)
+    // mock1 (position 1) should succeed
+    bool acquired1 = qutex.tryAcquire(*mock1, 2);
+    EXPECT_TRUE(acquired1);
+
+    // Reset for next test
+    qutex.isOwned = false;
+
+    // mock2 (position 2) should succeed
+    bool acquired2 = qutex.tryAcquire(*mock2, 2);
+    EXPECT_TRUE(acquired2);
+
+    // Reset for next test
+    qutex.isOwned = false;
+
+    // mock3 (position 3) should fail (in bottom 50%)
+    bool acquired3 = qutex.tryAcquire(*mock3, 2);
+    EXPECT_FALSE(acquired3);
+
+    // Reset for next test
+    qutex.isOwned = false;
+
+    // mock4 (position 4) should fail (in bottom 50%)
+    bool acquired4 = qutex.tryAcquire(*mock4, 2);
+    EXPECT_FALSE(acquired4);
+}
+
+// Test multi-lock acquisition with 3 required locks
+TEST_F(QutexTest, MultiLockAcquisitionThreeLocks) {
+    // Register 6 lockvokers
+    (void)qutex.registerInQueue(mock1);
+    (void)qutex.registerInQueue(mock2);
+    (void)qutex.registerInQueue(mock3);
+    (void)qutex.registerInQueue(mock4);
+    (void)qutex.registerInQueue(mock5);
+
+    // Create one more mock
+    int addr6 = 6;
+    auto mock6 = std::make_shared<MockLockerAndInvoker>(&addr6);
+    (void)qutex.registerInQueue(mock6);
+
+    // For nRequiredLocks = 3, need to be in top 66% (top 4 out of 6)
+    // Positions 1, 2, 3, 4 should succeed
+    // Positions 5, 6 should fail
+
+    bool acquired1 = qutex.tryAcquire(*mock1, 3);
+    EXPECT_TRUE(acquired1);
+    qutex.isOwned = false;
+
+    bool acquired2 = qutex.tryAcquire(*mock2, 3);
+    EXPECT_TRUE(acquired2);
+    qutex.isOwned = false;
+
+    bool acquired3 = qutex.tryAcquire(*mock3, 3);
+    EXPECT_TRUE(acquired3);
+    qutex.isOwned = false;
+
+    bool acquired4 = qutex.tryAcquire(*mock4, 3);
+    EXPECT_TRUE(acquired4);
+    qutex.isOwned = false;
+
+    bool acquired5 = qutex.tryAcquire(*mock5, 3);
+    EXPECT_FALSE(acquired5);
+
+    qutex.isOwned = false;
+    bool acquired6 = qutex.tryAcquire(*mock6, 3);
+    EXPECT_FALSE(acquired6);
+}
+
+// Test acquisition failure when already owned
+TEST_F(QutexTest, AcquisitionFailureWhenOwned) {
+    // Register mock1
+    (void)qutex.registerInQueue(mock1);
+
+    // Manually set as owned
+    qutex.isOwned = true;
+
+    // Try to acquire should fail
+    bool acquired = qutex.tryAcquire(*mock1, 1);
+    EXPECT_FALSE(acquired);
+    EXPECT_TRUE(qutex.isOwned);
+}
+
+// Test backoff with single item (should not rotate)
+TEST_F(QutexTest, BackoffSingleItem) {
+	// Register only one lockvoker
+	(void)qutex.registerInQueue(mock1);
+
+	// Set as owned first
+	qutex.isOwned = true;
+
+	// nRequiredLocks > 1 avoids the "front item with nRequiredLocks==1" guard
+	mock1->awakened = false;
+	qutex.backoff(*mock1, 2);
+
+	EXPECT_FALSE(qutex.isOwned);
+	EXPECT_EQ(qutex.queue.size(), 1u);
+	// Should not awaken since there's only one item
+	EXPECT_FALSE(mock1->awakened);
+}
+
+// Test backoff with multiple items and rotation
+TEST_F(QutexTest, BackoffWithRotation) {
+    // Register multiple lockvokers
+    (void)qutex.registerInQueue(mock1);
+    (void)qutex.registerInQueue(mock2);
+    (void)qutex.registerInQueue(mock3);
+
+    // Set as owned first
+    qutex.isOwned = true;
+
+    // mock1 should be at front initially
+    EXPECT_EQ(qutex.queue.front().get(), mock1.get());
+
+    // Backoff from mock1 (at front) with nRequiredLocks = 2
+    mock2->awakened = false;
+    qutex.backoff(*mock1, 2);
+
+    // mock1 should have been rotated to position 2
+    // mock2 should now be at front
+    EXPECT_EQ(qutex.queue.front().get(), mock2.get());
+    EXPECT_FALSE(qutex.isOwned);
+
+    // mock2 should have been awakened
+    EXPECT_TRUE(mock2->awakened);
+}
+
+// Test backoff with rotation to back when queue smaller than nRequiredLocks
+TEST_F(QutexTest, BackoffRotationToBack) {
+    // Register only 2 lockvokers
+    (void)qutex.registerInQueue(mock1);
+    (void)qutex.registerInQueue(mock2);
+
+    // Set as owned first
+    qutex.isOwned = true;
+
+    // mock1 should be at front initially
+    EXPECT_EQ(qutex.queue.front().get(), mock1.get());
+    EXPECT_EQ(qutex.queue.back().get(), mock2.get());
+
+    // Backoff from mock1 with nRequiredLocks = 5 (larger than queue size)
+    mock2->awakened = false;
+    qutex.backoff(*mock1, 5);
+
+    // mock1 should have been moved to the back
+    EXPECT_EQ(qutex.queue.front().get(), mock2.get());
+    EXPECT_EQ(qutex.queue.back().get(), mock1.get());
+    EXPECT_FALSE(qutex.isOwned);
+
+    // mock2 should have been awakened
+    EXPECT_TRUE(mock2->awakened);
+}
+
+// Test release functionality
+TEST_F(QutexTest, Release) {
+	// Register multiple lockvokers
+	(void)qutex.registerInQueue(mock1);
+	(void)qutex.registerInQueue(mock2);
+
+	ASSERT_TRUE(qutex.tryAcquire(*mock1, 1));
+
+	// Release should set isOwned to false and awaken front item
+	mock1->awakened = false;
+	qutex.release();
+
+	EXPECT_FALSE(qutex.isOwned);
+	EXPECT_TRUE(mock1->awakened);
+}
+
+// Test release without a prior acquire is rejected
+TEST_F(QutexTest, ReleaseWithoutAcquireThrows) {
+	qutex.isOwned = true;
+
+	EXPECT_THROW(qutex.release(), std::runtime_error);
+	EXPECT_TRUE(qutex.queue.empty());
+}
+
+// Test exception when trying to acquire from empty queue
+TEST_F(QutexTest, ExceptionOnEmptyQueueAcquisition) {
+    // Don't register any lockvokers
+    EXPECT_THROW(qutex.tryAcquire(*mock1, 1), std::runtime_error);
+}
+
+// Test exception when backoff called on empty queue
+TEST_F(QutexTest, ExceptionOnEmptyQueueBackoff) {
+    // Don't register any lockvokers
+    EXPECT_THROW(qutex.backoff(*mock1, 1), std::runtime_error);
+}
+
+// Test edge case: single lockvoker with multiple required locks
+TEST_F(QutexTest, SingleLockvokerMultipleRequiredLocks) {
+    // Register only one lockvoker
+    (void)qutex.registerInQueue(mock1);
+
+    // Should succeed regardless of nRequiredLocks when only one item
+    bool acquired = qutex.tryAcquire(*mock1, 5);
+    EXPECT_TRUE(acquired);
+    EXPECT_TRUE(qutex.isOwned);
+}
+
+// Test unregistration without locking
+TEST_F(QutexTest, UnregistrationWithoutLocking) {
+    // Register lockvoker
+    auto it1 = qutex.registerInQueue(mock1);
+    EXPECT_EQ(qutex.queue.size(), 1);
+
+    // Unregister without locking
+    qutex.unregisterFromQueue(it1, false);
+    EXPECT_EQ(qutex.queue.size(), 0);
+}
+
+} // namespace smo