- Add assertions in MutexLocker/MonitorLocker to ensure that the code enclosed

runtime/vm/thread_test.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "platform/assert.h"
 #include "vm/isolate.h"
 #include "vm/lockers.h"
 #include "vm/unit_test.h"
 #include "vm/profiler.h"
 #include "vm/safepoint.h"
@@ skipping 26 matching lines @@
 
 UNIT_TEST_CASE(Monitor) {
   // This unit test case needs a running isolate.
   Dart_CreateIsolate(
       NULL, NULL, bin::isolate_snapshot_buffer, NULL, NULL, NULL);
   OSThread* thread = OSThread::Current();
   // Thread interrupter interferes with this test, disable interrupts.
   thread->DisableThreadInterrupts();
   Monitor* monitor = new Monitor();
   monitor->Enter();
+  EXPECT_EQ(false, monitor->TryEnter());
+  monitor->Exit();
+  EXPECT_EQ(true, monitor->TryEnter());
   monitor->Exit();
 
   const int kNumAttempts = 5;
   int attempts = 0;
   while (attempts < kNumAttempts) {
     MonitorLocker ml(monitor);
     int64_t start = OS::GetCurrentTimeMillis();
     int64_t wait_time = 2017;
     Monitor::WaitResult wait_result = ml.Wait(wait_time);
     int64_t stop = OS::GetCurrentTimeMillis();
@@ skipping 512 matching lines @@
       TransitionVMToBlocked transition(thread);
       MonitorLocker ml(&done_monitor);
       if (done) {
         break;
       }
     }
   }
 }
 
 }  // namespace dart