GTest原始碼剖析——RUN_ALL_TESTS

1 RUN_ALL_TESTS()原始碼分析

RUN_ALL_TESTS()之前是巨集定義，現在改變為函式。其實際上僅僅是呼叫了UnitTest單例的Run()函式。

原始碼如下：
其實現為獲取一個UnitTest單例，然後呼叫其Run()函式

int RUN_ALL_TESTS();

inline int RUN_ALL_TESTS() 
{
  return ::testing::UnitTest::GetInstance()->Run();
}

實際上，RUN_ALL_TESTS()的操作主要是，依次呼叫
1. UnitTest::Run()
2. UnitTest::Run()
3. UnitTestImpl::RunAllTests()
4. TestCase::Run()
5. TestCase::Run()
6. Test::Run()
7. Test::TestBody()

並在這些函式裡設定相應的操作，以保證測試執行的正確性。

1.1 UnitTest::Run()

UnitTest::Run()主要設定了相關死亡測試的設定。真正的實現交給了RunAllTest()

1. 如果忽略死亡測試和支援跨平臺及異常處理的邏輯，其實現可以簡化為：

int UnitTest::Run() 
{
  return internal::HandleExceptionsInMethodIfSupported(
      impl(),
      &internal::UnitTestImpl::RunAllTests,
      "auxiliary test code
 
 (environments or event listeners)") ? 0 : 1;
}

1. 如果我們在剔除HandleExceptionsInMethodIfSupported對支援跨平臺及異常處理的邏輯，其實現直接簡化為：

int UnitTest::Run() 
{
  return impl->RunAllTests();
}

1. 全部原始碼如下：

int UnitTest::Run() 
{
  const bool in_death_test_child_process = GTEST_FLAG(internal_run_death_test).length() > 0
 
;

  const internal::ScopedPrematureExitFile premature_exit_file(
      in_death_test_child_process ?
      NULL : internal::posix::GetEnv("TEST_PREMATURE_EXIT_FILE"));

  impl()->set_catch_exceptions(GTEST_FLAG(catch_exceptions));

#if GTEST_HAS_SEH
  if (impl()->catch_exceptions() || in_death_test_child_process) 
  {
# if !GTEST_OS_WINDOWS_MOBILE && !GTEST_OS_WINDOWS_PHONE && !GTEST_OS_WINDOWS_RT
    SetErrorMode(SEM_FAILCRITICALERRORS | SEM_NOALIGNMENTFAULTEXCEPT |
                 SEM_NOGPFAULTERRORBOX | SEM_NOOPENFILEERRORBOX);
# endif  

# if (defined(_MSC_VER) || GTEST_OS_WINDOWS_MINGW) && !GTEST_OS_WINDOWS_MOBILE
    _set_error_mode(_OUT_TO_STDERR);
# endif

# if _MSC_VER >= 1400 && !GTEST_OS_WINDOWS_MOBILE
    if (!GTEST_FLAG(break_on_failure))
      _set_abort_behavior(0x0, flags:_WRITE_ABORT_MSG | _CALL_REPORTFAULT); 
# endif
  }
#endif  // GTEST_HAS_SEH

  return internal::HandleExceptionsInMethodIfSupported(
      impl(),
      &internal::UnitTestImpl::RunAllTests,
      "auxiliary test code (environments or event listeners)") ? 0 : 1;
}

1.2 HandleExceptionsInMethodIfSupported

HandleSehExceptionsInMethodIfSupported 主要用於捕獲異常和跨平臺處理。
這裡可以看出GTest對於跨平臺的支援和捕獲異常的不遺餘力。其實這麼多程式碼主要是為了實現如下的功能：

Result HandleExceptionsInMethodIfSupported(T* object, Result (T::*method)(), const char* location) {
    return (object->*method)();
}

全部原始碼如下：

template <class T, typename Result>
Result HandleExceptionsInMethodIfSupported(T* object, Result (T::*method)(), const char* location) {
  if (internal::GetUnitTestImpl()->catch_exceptions()) 
  {
#if GTEST_HAS_EXCEPTIONS
    try 
    {
      return HandleSehExceptionsInMethodIfSupported(object, method, location);
    } 
    catch (const internal::GoogleTestFailureException&) 
    { 
      throw;
    } 
    catch (const std::exception& e) 
    { 
      internal::ReportFailureInUnknownLocation(
          TestPartResult::kFatalFailure,
          FormatCxxExceptionMessage(e.what(), location));
    } 
    catch (...) 
    {  
      internal::ReportFailureInUnknownLocation(
          TestPartResult::kFatalFailure,
          FormatCxxExceptionMessage(NULL, location));
    }
    return static_cast<Result>(0);
#else
    return HandleSehExceptionsInMethodIfSupported(object, method, location);
#endif  // GTEST_HAS_EXCEPTIONS
  } 
  else 
  {
    return (object->*method)();
  }
}

//HandleSehExceptionsInMethodIfSupported 主要用於捕獲異常。
template <class T, typename Result>
Result HandleSehExceptionsInMethodIfSupported(
    T* object, Result (T::*method)(), const char* location) 
{
#if GTEST_HAS_SEH
  __try 
  {
    return (object->*method)();
  } 
  __except (internal::UnitTestOptions::GTestShouldProcessSEH( GetExceptionCode())) 
  {
    std::string* exception_message = FormatSehExceptionMessage(
        GetExceptionCode(), location);
    internal::ReportFailureInUnknownLocation(TestPartResult::kFatalFailure,
                                             *exception_message);
    delete exception_message;
    return static_cast<Result>(0);
  }
#else
  (void)location;
  return (object->*method)();
#endif  // GTEST_HAS_SEH
}

1.3 UnitTestImpl::RunAllTests()

bool UnitTestImpl::RunAllTests() 
{
  // Makes sure InitGoogleTest() was called.
  if (!GTestIsInitialized()) 
  {
    printf("%s",
           "\nThis test program did NOT call ::testing::InitGoogleTest "
           "before calling RUN_ALL_TESTS().  Please fix it.\n");
    return false;
  }

  // Do not run any test if the --help flag was specified.
  if (g_help_flag)
    return true;

  // Repeats the call to the post-flag parsing initialization in case the
  // user didn't call InitGoogleTest.
  PostFlagParsingInit();

  // Even if sharding is not on, test runners may want to use the
  // GTEST_SHARD_STATUS_FILE to query whether the test supports the sharding
  // protocol.
  internal::WriteToShardStatusFileIfNeeded();

  //執行死亡測試
  bool in_subprocess_for_death_test = false;
#if GTEST_HAS_DEATH_TEST
  in_subprocess_for_death_test = (internal_run_death_test_flag_.get() != NULL);
# if defined(GTEST_EXTRA_DEATH_TEST_CHILD_SETUP_)
  if (in_subprocess_for_death_test) 
  {
    GTEST_EXTRA_DEATH_TEST_CHILD_SETUP_();
  }
# endif
#endif  // GTEST_HAS_DEATH_TEST

    //應該是檢查environments相關的設定，可以暫不關心。
  const bool should_shard = ShouldShard(kTestTotalShards, kTestShardIndex,
                                        in_subprocess_for_death_test);

    //匹配Filter,對所有的測試用例進行匹配，確定是否需要執行該測試用例
  const bool has_tests_to_run = FilterTests(should_shard
                                              ? HONOR_SHARDING_PROTOCOL
                                              : IGNORE_SHARDING_PROTOCOL) > 0;

  // Lists the tests and exits if the --gtest_list_tests flag was specified.
  if (GTEST_FLAG(list_tests)) 
  {
    ListTestsMatchingFilter();
    return true;
  }

  //設定隨機執行測試用例
  random_seed_ = GTEST_FLAG(shuffle) ? GetRandomSeedFromFlag(GTEST_FLAG(random_seed)) : 0;

  // True iff at least one test has failed.
  bool failed = false;

  //獲取事件監聽器，如果使用者訂閱了某事件，則在適當的時間點上報該事件，讓使用者進行額外的操作
  TestEventListener* repeater = listeners()->repeater();

  start_timestamp_ = GetTimeInMillis();

  //上報事件OnTestProgramStart
  repeater->OnTestProgramStart(*parent_);

  const int repeat = in_subprocess_for_death_test ? 1 : GTEST_FLAG(repeat);

  const bool forever = repeat < 0;
  for (int i = 0; forever || i != repeat; i++) 
  {
    //清除所有非AddHoc的測試結果，為後續執行做準備。
    ClearNonAdHocTestResult();

    const TimeInMillis start = GetTimeInMillis();

    // Shuffles test cases and tests if requested.
    if (has_tests_to_run && GTEST_FLAG(shuffle)) 
    {
      random()->Reseed(random_seed_);
      ShuffleTests();
    }

    // Tells the unit test event listeners that the tests are about to start.
    repeater->OnTestIterationStart(*parent_, i);

    // Runs each test case if there is at least one test to run.
    if (has_tests_to_run) 
    {
      // Sets up all environments beforehand.
      repeater->OnEnvironmentsSetUpStart(*parent_);
      ForEach(environments_, SetUpEnvironment);
      repeater->OnEnvironmentsSetUpEnd(*parent_);

      // Runs the tests only if there was no fatal failure during global
      // set-up.
      if (!Test::HasFatalFailure()) 
      {
        //逐個執行TestCase，即最終執行所有的TestBody()
        for (int test_index = 0; test_index < total_test_case_count(); test_index++) 
        {
          GetMutableTestCase(test_index)->Run();
        }
      }

      // Tears down all environments in reverse order afterwards.
      repeater->OnEnvironmentsTearDownStart(*parent_);
      std::for_each(environments_.rbegin(), environments_.rend(),TearDownEnvironment);
      repeater->OnEnvironmentsTearDownEnd(*parent_);
    }

    elapsed_time_ = GetTimeInMillis() - start;

    // Tells the unit test event listener that the tests have just finished.
    repeater->OnTestIterationEnd(*parent_, i);

    // Gets the result and clears it.
    if (!Passed()) 
    {
      failed = true;
    }

    UnshuffleTests();

    if (GTEST_FLAG(shuffle)) 
    {
      // Picks a new random seed for each iteration.
      random_seed_ = GetNextRandomSeed(random_seed_);
    }
  }

  //上報事件OnTestProgramEnd
  repeater->OnTestProgramEnd(*parent_);

  return !failed;
}

1.5 TestCase::Run()

// Runs every test in this TestCase.
void TestCase::Run() 
{
  if (!should_run_) return;

  internal::UnitTestImpl* const impl = internal::GetUnitTestImpl();
  impl->set_current_test_case(this);

  TestEventListener* repeater = UnitTest::GetInstance()->listeners().repeater();

  //上報事件OnTestCaseStart
  repeater->OnTestCaseStart(*this);
  impl->os_stack_trace_getter()->UponLeavingGTest();

  //for TEST_F
  internal::HandleExceptionsInMethodIfSupported(
      this, &TestCase::RunSetUpTestCase, "SetUpTestCase()");

  const internal::TimeInMillis start = internal::GetTimeInMillis();

  //逐個執行TestCase裡的Test，即最終執行所有的TestBody()
  for (int i = 0; i < total_test_count(); i++) 
  {
    GetMutableTestInfo(i)->Run();
  }
  elapsed_time_ = internal::GetTimeInMillis() - start;

  impl->os_stack_trace_getter()->UponLeavingGTest();

  //for TEST_F
  internal::HandleExceptionsInMethodIfSupported(
      this, &TestCase::RunTearDownTestCase, "TearDownTestCase()");

  repeater->OnTestCaseEnd(*this);
  impl->set_current_test_case(NULL);
}

1.6 TestCase::Run()

void TestInfo::Run() 
{
  if (!should_run_) return;

  // Tells UnitTest where to store test result.
  internal::UnitTestImpl* const impl = internal::GetUnitTestImpl();
  impl->set_current_test_info(this);

  TestEventListener* repeater = UnitTest::GetInstance()->listeners().repeater();

  // Notifies the unit test event listeners that a test is about to start.
  repeater->OnTestStart(*this);

  const TimeInMillis start = internal::GetTimeInMillis();

  impl->os_stack_trace_getter()->UponLeavingGTest();

  // Creates the test object.
  // 此處確保所有的TEST_P裡呼叫GetParam()的正確性
  Test* const test = internal::HandleExceptionsInMethodIfSupported(
      factory_, &internal::TestFactoryBase::CreateTest,
      "the test fixture's constructor");

  // Runs the test only if the test object was created and its
  // constructor didn't generate a fatal failure.
  if ((test != NULL) && !Test::HasFatalFailure()) 
  {
    // This doesn't throw as all user code that can throw are wrapped into
    // exception handling code.
    test->Run();
  }

  // Deletes the test object.
  impl->os_stack_trace_getter()->UponLeavingGTest();
  internal::HandleExceptionsInMethodIfSupported(
      test, &Test::DeleteSelf_, "the test fixture's destructor");

  result_.set_elapsed_time(internal::GetTimeInMillis() - start);

  // Notifies the unit test event listener that a test has just finished.
  repeater->OnTestEnd(*this);

  // Tells UnitTest to stop associating assertion results to this
  // test.
  impl->set_current_test_info(NULL);
}

1.7 Test::Run()

// Runs the test and updates the test result.
void Test::Run() 
{
  if (!HasSameFixtureClass()) return;

  internal::UnitTestImpl* const impl = internal::GetUnitTestImpl();
  impl->os_stack_trace_getter()->UponLeavingGTest();

  //for TEST_F
  internal::HandleExceptionsInMethodIfSupported(this, &Test::SetUp, "SetUp()");

  // We will run the test only if SetUp() was successful.
  if (!HasFatalFailure()) 
  {
    impl->os_stack_trace_getter()->UponLeavingGTest();
    internal::HandleExceptionsInMethodIfSupported(
        this, &Test::TestBody, "the test body");
  }

  // However, we want to clean up as much as possible.  Hence we will
  // always call TearDown(), even if SetUp() or the test body has
  // failed.
  impl->os_stack_trace_getter()->UponLeavingGTest();

  ／/ for TEST_F
  internal::HandleExceptionsInMethodIfSupported(
      this, &Test::TearDown, "TearDown()");
}

2 參考

ZhaiPillar
2017-09-17