[work-serializer] Isolate test event engines (#34831)

Previously event engines could exist past test boundaries, which messed
up stats collection in later tests.

test/core/gprpp/work_serializer_test.cc

@@ -51,28 +51,37 @@ using grpc_event_engine::experimental::WaitForSingleOwner;
 
 namespace grpc_core {
 namespace {
-TEST(WorkSerializerTest, NoOp) { WorkSerializer lock(GetDefaultEventEngine()); }
+TEST(WorkSerializerTest, NoOp) {
+  auto lock = std::make_unique<WorkSerializer>(GetDefaultEventEngine());
+  lock.reset();
+  WaitForSingleOwner(GetDefaultEventEngine());
+}
 
 TEST(WorkSerializerTest, ExecuteOneRun) {
-  WorkSerializer lock(GetDefaultEventEngine());
+  auto lock = std::make_unique<WorkSerializer>(GetDefaultEventEngine());
   gpr_event done;
   gpr_event_init(&done);
-  lock.Run([&done]() { gpr_event_set(&done, reinterpret_cast<void*>(1)); },
-           DEBUG_LOCATION);
+  lock->Run([&done]() { gpr_event_set(&done, reinterpret_cast<void*>(1)); },
+            DEBUG_LOCATION);
   EXPECT_TRUE(gpr_event_wait(&done, grpc_timeout_seconds_to_deadline(5)) !=
               nullptr);
+  lock.reset();
+  WaitForSingleOwner(GetDefaultEventEngine());
 }
 
 TEST(WorkSerializerTest, ExecuteOneScheduleAndDrain) {
-  WorkSerializer lock(GetDefaultEventEngine());
+  auto lock = std::make_unique<WorkSerializer>(GetDefaultEventEngine());
   gpr_event done;
   gpr_event_init(&done);
-  lock.Schedule([&done]() { gpr_event_set(&done, reinterpret_cast<void*>(1)); },
-                DEBUG_LOCATION);
+  lock->Schedule(
+      [&done]() { gpr_event_set(&done, reinterpret_cast<void*>(1)); },
+      DEBUG_LOCATION);
   EXPECT_EQ(gpr_event_get(&done), nullptr);
-  lock.DrainQueue();
+  lock->DrainQueue();
   EXPECT_TRUE(gpr_event_wait(&done, grpc_timeout_seconds_to_deadline(5)) !=
               nullptr);
+  lock.reset();
+  WaitForSingleOwner(GetDefaultEventEngine());
 }
 
 class TestThread {
@@ -125,13 +134,15 @@ class TestThread {
 };
 
 TEST(WorkSerializerTest, ExecuteMany) {
-  WorkSerializer lock(GetDefaultEventEngine());
+  auto lock = std::make_unique<WorkSerializer>(GetDefaultEventEngine());
   {
     std::vector<std::unique_ptr<TestThread>> threads;
     for (size_t i = 0; i < 10; ++i) {
-      threads.push_back(std::make_unique<TestThread>(&lock));
+      threads.push_back(std::make_unique<TestThread>(lock.get()));
     }
   }
+  lock.reset();
+  WaitForSingleOwner(GetDefaultEventEngine());
 }
 
 class TestThreadScheduleAndDrain {
@@ -186,26 +197,31 @@ class TestThreadScheduleAndDrain {
 };
 
 TEST(WorkSerializerTest, ExecuteManyScheduleAndDrain) {
-  WorkSerializer lock(GetDefaultEventEngine());
+  auto lock = std::make_unique<WorkSerializer>(GetDefaultEventEngine());
   {
     std::vector<std::unique_ptr<TestThreadScheduleAndDrain>> threads;
     for (size_t i = 0; i < 10; ++i) {
-      threads.push_back(std::make_unique<TestThreadScheduleAndDrain>(&lock));
+      threads.push_back(
+          std::make_unique<TestThreadScheduleAndDrain>(lock.get()));
     }
   }
+  lock.reset();
+  WaitForSingleOwner(GetDefaultEventEngine());
 }
 
 TEST(WorkSerializerTest, ExecuteManyMixedRunScheduleAndDrain) {
-  WorkSerializer lock(GetDefaultEventEngine());
+  auto lock = std::make_unique<WorkSerializer>(GetDefaultEventEngine());
   {
     std::vector<std::unique_ptr<TestThread>> run_threads;
     std::vector<std::unique_ptr<TestThreadScheduleAndDrain>> schedule_threads;
     for (size_t i = 0; i < 10; ++i) {
-      run_threads.push_back(std::make_unique<TestThread>(&lock));
+      run_threads.push_back(std::make_unique<TestThread>(lock.get()));
       schedule_threads.push_back(
-          std::make_unique<TestThreadScheduleAndDrain>(&lock));
+          std::make_unique<TestThreadScheduleAndDrain>(lock.get()));
     }
   }
+  lock.reset();
+  WaitForSingleOwner(GetDefaultEventEngine());
 }
 
 // Tests that work serializers allow destruction from the last callback
@@ -228,6 +244,7 @@ TEST(WorkSerializerTest, WorkSerializerDestructionRace) {
     lock->Run([&]() { notification.Notify(); }, DEBUG_LOCATION);
     t1.join();
   }
+  WaitForSingleOwner(GetDefaultEventEngine());
 }
 
 // Tests racy conditions when the last callback triggers work
@@ -248,6 +265,7 @@ TEST(WorkSerializerTest, WorkSerializerDestructionRaceMultipleThreads) {
   for (auto& thread : threads) {
     thread.join();
   }
+  WaitForSingleOwner(GetDefaultEventEngine());
 }
 
 TEST(WorkSerializerTest, MetricsWork) {
@@ -255,11 +273,11 @@ TEST(WorkSerializerTest, MetricsWork) {
     GTEST_SKIP() << "Work serializer dispatch experiment not enabled";
   }
 
-  WorkSerializer serializer(GetDefaultEventEngine());
+  auto serializer = std::make_unique<WorkSerializer>(GetDefaultEventEngine());
   auto schedule_sleep = [&serializer](absl::Duration how_long) {
     ExecCtx exec_ctx;
     auto n = std::make_shared<Notification>();
-    serializer.Run(
+    serializer->Run(
         [how_long, n]() {
           absl::SleepFor(how_long);
           n->Notify();
@@ -349,6 +367,9 @@ TEST(WorkSerializerTest, MetricsWork) {
                 .Percentile(0.5),
             diff->histogram(GlobalStats::Histogram::kWorkSerializerWorkTimeMs)
                 .Percentile(0.5));
+
+  serializer.reset();
+  WaitForSingleOwner(GetDefaultEventEngine());
 }
 
 #ifndef NDEBUG
@@ -395,6 +416,9 @@ TEST(WorkSerializerTest, RunningInWorkSerializer) {
   work_serializer2->Run([&done2]() { done2.Notify(); }, DEBUG_LOCATION);
   done1.WaitForNotification();
   done2.WaitForNotification();
+  work_serializer1.reset();
+  work_serializer2.reset();
+  WaitForSingleOwner(GetDefaultEventEngine());
 }
 #endif