Add instant leak check capabilities to gmock (#4215)

docs/gmock_cheat_sheet.md

@@ -219,6 +219,17 @@ verified:
 Mock::AllowLeak(&mock_obj);
 ```
 
+Furthermore you can perform instant leak checks. This may help tracing down leaking
+mock objects when running a larger test suite:
+
+```cpp
+Mock::CheckLeakInstant();
+```
+You can use this for example by adding following to the end of your test cases:
+```cpp
+ASSERT_EQ(Mock::CheckLeakInstant(),true);
+```
+
 ## Mock Classes
 
 gMock defines a convenient mock class template

googlemock/include/gmock/gmock-spec-builders.h

@@ -370,6 +370,12 @@ class GTEST_API_ Mock {
   static void AllowLeak(const void* mock_obj)
       GTEST_LOCK_EXCLUDED_(internal::g_gmock_mutex);
 
+  // Tells Google Mock to instantly check for leftover mock objects and report
+  // them if there are.
+  // Returns false if there are leftover mock objects and true otherwise.
+  static bool CheckLeakInstant(void)
+      GTEST_LOCK_EXCLUDED_(internal::g_gmock_mutex);
+
   // Verifies and clears all expectations on the given mock object.
   // If the expectations aren't satisfied, generates one or more
   // Google Test non-fatal failures and returns false.

googlemock/src/gmock-spec-builders.cc

@@ -453,9 +453,11 @@ static CallReaction intToCallReaction(int mock_behavior) {
 }  // namespace internal
 
 // Class Mock.
-
 namespace {
 
+class MockObjectRegistry;
+bool ReportMockObjectRegistryLeaks(MockObjectRegistry const& reg);
+
 typedef std::set<internal::UntypedFunctionMockerBase*> FunctionMockers;
 
 // The current state of a mock object.  Such information is needed for
@@ -489,42 +491,8 @@ class MockObjectRegistry {
   // object alive.  Therefore we report any living object as test
   // failure, unless the user explicitly asked us to ignore it.
   ~MockObjectRegistry() {
-    if (!GMOCK_FLAG_GET(catch_leaked_mocks)) return;
     internal::MutexLock l(&internal::g_gmock_mutex);
-
-    int leaked_count = 0;
-    for (StateMap::const_iterator it = states_.begin(); it != states_.end();
-         ++it) {
-      if (it->second.leakable)  // The user said it's fine to leak this object.
-        continue;
-
-      // FIXME: Print the type of the leaked object.
-      // This can help the user identify the leaked object.
-      std::cout << "\n";
-      const MockObjectState& state = it->second;
-      std::cout << internal::FormatFileLocation(state.first_used_file,
-                                                state.first_used_line);
-      std::cout << " ERROR: this mock object";
-      if (!state.first_used_test.empty()) {
-        std::cout << " (used in test " << state.first_used_test_suite << "."
-                  << state.first_used_test << ")";
-      }
-      std::cout << " should be deleted but never is. Its address is @"
-                << it->first << ".";
-      leaked_count++;
-    }
-    if (leaked_count > 0) {
-      std::cout << "\nERROR: " << leaked_count << " leaked mock "
-                << (leaked_count == 1 ? "object" : "objects")
-                << " found at program exit. Expectations on a mock object are "
-                   "verified when the object is destructed. Leaking a mock "
-                   "means that its expectations aren't verified, which is "
-                   "usually a test bug. If you really intend to leak a mock, "
-                   "you can suppress this error using "
-                   "testing::Mock::AllowLeak(mock_object), or you may use a "
-                   "fake or stub instead of a mock.\n";
-      std::cout.flush();
-      ::std::cerr.flush();
+    if (!ReportMockObjectRegistryLeaks(*this)) {
       // RUN_ALL_TESTS() has already returned when this destructor is
       // called.  Therefore we cannot use the normal Google Test
       // failure reporting mechanism.
@@ -534,15 +502,70 @@ class MockObjectRegistry {
       _Exit(1);  // We cannot call exit() as it is not reentrant and
                  // may already have been called.
 #endif
+    } else {
+      return;
     }
   }
 
+  StateMap const& states() const { return states_; }
   StateMap& states() { return states_; }
 
  private:
   StateMap states_;
 };
 
+// Checks the given MockObjectRegistry for leaks (i.e. MockObjectStates objects
+// which are still in the given MockObjectRegistry and are not marked as
+// leakable) and reports them. Furthermore it returns false if leaks were
+// determined and true otherwise.
+// NOTE:
+// It is the callers job to make calls on "reg" safe, e.g. locking its mutex (if
+// there is any).
+bool ReportMockObjectRegistryLeaks(MockObjectRegistry const& reg) {
+  if (!GMOCK_FLAG_GET(catch_leaked_mocks)) return true;
+
+  typedef std::map<const void*, MockObjectState> StateMap;
+
+  int leaked_count = 0;
+  for (StateMap::const_iterator it = reg.states().begin();
+       it != reg.states().end(); ++it) {
+    if (it->second.leakable)  // The user said it's fine to leak this object.
+      continue;
+
+    // FIXME: Print the type of the leaked object.
+    // This can help the user identify the leaked object.
+    std::cout << "\n";
+    const MockObjectState& state = it->second;
+    std::cout << internal::FormatFileLocation(state.first_used_file,
+                                              state.first_used_line);
+    std::cout << " ERROR: this mock object";
+    if (!state.first_used_test.empty()) {
+      std::cout << " (used in test " << state.first_used_test_suite << "."
+                << state.first_used_test << ")";
+    }
+    std::cout << " should be deleted but never is. Its address is @"
+              << it->first << ".";
+    leaked_count++;
+  }
+  if (leaked_count > 0) {
+    std::cout << "\nERROR: " << leaked_count << " leaked mock "
+              << (leaked_count == 1 ? "object" : "objects")
+              << " found at program exit. Expectations on a mock object are "
+                 "verified when the object is destructed. Leaking a mock "
+                 "means that its expectations aren't verified, which is "
+                 "usually a test bug. If you really intend to leak a mock, "
+                 "you can suppress this error using "
+                 "testing::Mock::AllowLeak(mock_object), or you may use a "
+                 "fake or stub instead of a mock.\n";
+    std::cout.flush();
+    ::std::cerr.flush();
+
+    return false;
+  }
+
+  return true;
+}
+
 // Protected by g_gmock_mutex.
 MockObjectRegistry g_mock_object_registry;
 
@@ -615,6 +638,13 @@ void Mock::AllowLeak(const void* mock_obj)
   g_mock_object_registry.states()[mock_obj].leakable = true;
 }
 
+bool Mock::CheckLeakInstant(void)
+    GTEST_LOCK_EXCLUDED_(internal::g_gmock_mutex) {
+  internal::MutexLock l(&internal::g_gmock_mutex);
+
+  return ReportMockObjectRegistryLeaks(g_mock_object_registry);
+}
+
 // Verifies and clears all expectations on the given mock object.  If
 // the expectations aren't satisfied, generates one or more Google
 // Test non-fatal failures and returns false.

googlemock/test/gmock_leak_test.py

@@ -37,6 +37,8 @@ PROGRAM_PATH = gmock_test_utils.GetTestExecutablePath('gmock_leak_test_')
 TEST_WITH_EXPECT_CALL = [PROGRAM_PATH, '--gtest_filter=*ExpectCall*']
 TEST_WITH_ON_CALL = [PROGRAM_PATH, '--gtest_filter=*OnCall*']
 TEST_MULTIPLE_LEAKS = [PROGRAM_PATH, '--gtest_filter=*MultipleLeaked*']
+TEST_INSTANT_LEAKS = [PROGRAM_PATH, '--gtest_filter=*InstantLeak*']
+TEST_INSTANT_LEAKS_ENV = [PROGRAM_PATH, '--gtest_filter=*InstantAllowedByEnvironment*']
 
 environ = gmock_test_utils.environ
 SetEnvVar = gmock_test_utils.SetEnvVar
@@ -108,6 +110,22 @@ class GMockLeakTest(gmock_test_utils.TestCase):
         ).exit_code,
     )
 
+  def testInstantLeakCheck(self):
+    self.assertEqual(
+        0,
+        gmock_test_utils.Subprocess(
+            TEST_INSTANT_LEAKS + ['--gmock_catch_leaked_mocks=1'], env=environ
+        ).exit_code,
+    )
+
+  def testInstantLeakCheckEnv(self):
+    self.assertEqual(
+        0,
+        gmock_test_utils.Subprocess(
+            TEST_INSTANT_LEAKS_ENV + ['--gmock_catch_leaked_mocks=0'], env=environ
+        ).exit_code,
+    )
+
 
 if __name__ == '__main__':
   gmock_test_utils.Main()

googlemock/test/gmock_leak_test_.cc

@@ -93,7 +93,68 @@ TEST(LeakTest, CatchesMultipleLeakedMockObjects) {
 
   // Makes sure Google Mock's leak detector can change the exit code
   // to 1 even when the code is already exiting with 0.
+  // Additionally the instant leak check should:
+  // a) return false since mock objects are leaked
+  // b) not influence the outcome of the on program end mock object leak check.
+  ASSERT_EQ(testing::Mock::CheckLeakInstant(), false);
+
   exit(0);
 }
 
+TEST(LeakTest, InstantNoLeak) {
+  MockFoo* foo = new MockFoo;
+
+  EXPECT_CALL(*foo, DoThis());
+  foo->DoThis();
+
+  delete foo;
+  // Since foo is properly deleted instant leak check should not see a leaked
+  // mock object and therefore return true.
+  ASSERT_EQ(testing::Mock::CheckLeakInstant(), true);
+}
+
+TEST(LeakTest, InstantLeak) {
+  MockFoo* foo = new MockFoo;
+
+  EXPECT_CALL(*foo, DoThis());
+  foo->DoThis();
+
+  // At this point foo is still allocated. Calling the instant leak check should
+  // detect it and return false.
+  ASSERT_EQ(testing::Mock::CheckLeakInstant(), false);
+
+  // Free foo in order to not fail the end of program leak check.
+  delete foo;
+}
+
+TEST(LeakTest, InstantLeakAllowed) {
+  MockFoo* foo = new MockFoo;
+  testing::Mock::AllowLeak(foo);
+
+  EXPECT_CALL(*foo, DoThis());
+  foo->DoThis();
+
+  // At this point foo is still allocated However since we made foo a leakable
+  // mock object with AllowLeak() the instant leak check should ignore it and
+  // return true.
+  ASSERT_EQ(testing::Mock::CheckLeakInstant(), true);
+
+  // Free foo in order to not fail the end of program leak check.
+  delete foo;
+}
+
+TEST(LeakTest, InstantAllowedByEnvironment) {
+  MockFoo* foo = new MockFoo;
+
+  EXPECT_CALL(*foo, DoThis());
+  foo->DoThis();
+
+  // At this point foo is still allocated. However since we made foo a leakable
+  // via setting environment variable --gmock_catch_leaked_mocks=0 therefore
+  // true should be returned.
+  ASSERT_EQ(testing::Mock::CheckLeakInstant(), true);
+
+  // Free foo in order to not fail the end of program leak check.
+  delete foo;
+}
 }  // namespace

googlemock/test/gmock_output_test.py

@@ -166,12 +166,16 @@ class GMockOutputTest(gmock_test_utils.TestCase):
     # The normalized output should match the golden file.
     self.assertEqual(golden, output)
 
-    # The raw output should contain 2 leaked mock object errors for
+    # The raw output should contain 4 leaked mock object errors for
     # test GMockOutputTest.CatchesLeakedMocks.
+    # Two from the at end of program check and two from the instant leak check
+    # within GMockOutputTest.CatchesLeakedMocks.
     self.assertEqual(
         [
             'GMockOutputTest.CatchesLeakedMocks',
             'GMockOutputTest.CatchesLeakedMocks',
+            'GMockOutputTest.CatchesLeakedMocks',
+            'GMockOutputTest.CatchesLeakedMocks',
         ],
         leaky_tests,
     )

googlemock/test/gmock_output_test_.cc

@@ -251,6 +251,8 @@ TEST_F(GMockOutputTest, CatchesLeakedMocks) {
   foo2->Bar2(1, 1);
 
   // Both foo1 and foo2 are deliberately leaked.
+  // Call the instant leak check in order to validate it's output.
+  ASSERT_EQ(testing::Mock::CheckLeakInstant(),false);
 }
 
 MATCHER_P2(IsPair, first, second, "") {

googlemock/test/gmock_output_test_golden.txt

@@ -304,6 +304,11 @@ FILE:#:
 Stack trace:
 [       OK ] GMockOutputTest.ExplicitActionsRunOutWithDefaultAction
 [ RUN      ] GMockOutputTest.CatchesLeakedMocks
+
+FILE:#: ERROR: this mock object should be deleted but never is. Its address is @0x#.
+FILE:#: ERROR: this mock object should be deleted but never is. Its address is @0x#.
+FILE:#: ERROR: this mock object should be deleted but never is. Its address is @0x#.
+ERROR: 3 leaked mock objects found at program exit. Expectations on a mock object are verified when the object is destructed. Leaking a mock means that its expectations aren't verified, which is usually a test bug. If you really intend to leak a mock, you can suppress this error using testing::Mock::AllowLeak(mock_object), or you may use a fake or stub instead of a mock.
 [       OK ] GMockOutputTest.CatchesLeakedMocks
 [ RUN      ] GMockOutputTest.PrintsMatcher
 FILE:#: Failure