TL;DR: 您可以使用 GMock 向 Microsoft 本机 C++ 单元测试添加模拟功能。看我的答案请参阅下文了解详细信息。
我想开始向我现有的一组本机单元测试添加模拟。这些测试是使用 Microsoft 编写的CppUnitTestFramework框架，不支持模拟。我真的不想将整个测试套件转换为另一个框架只是为了添加一些模拟。
谷歌的GMock框架似乎提供了我需要的一切，并且文档表明它可以与除gtest。因此，请使用博客文章中的建议，例如this one，我创建了几个单元测试。
TEST_MODULE_INITIALIZE(ModuleInitialize)
{
// Enable google mock
GTEST_FLAG(throw_on_failure) = true;
int argc = 0;
TCHAR **argv = nullptr;
InitGoogleMock(&argc, argv);
}
TEST_CLASS(GMockTests)
{
public:
MockTestClass _mockObj;
TEST_METHOD(Method1_ParamIsOne_Method2CalledWithOne)
{
EXPECT_CALL(_mockObj, Method2(1)).Times(1);
_mockObj.Method1(1);
}
TEST_METHOD(Method1_ParamIsZero_IntentionallyFail)
{
// Expectation will fail
EXPECT_CALL(_mockObj, Method2(1)).Times(1);
_mockObj.Method1(0);
}
};
结果并不令人满意。期望确实有效（第一个方法通过），但如果任何期望失败，则整个运行将中止，测试输出中仅显示以下无用消息：
[3/27/2019 11:39:17 AM Error] The active test run was aborted. Reason:
[3/27/2019 11:39:17 AM Informational] ========== Run test finished: 0 run (0:00:22.3042194) ==========
Visual Studio 测试资源管理器窗口也没有指出问题所在。它只是显示一个测试成功，而另一个测试未运行：
所以我从这个集成中寻找的是：
我能够得到GMock正确工作CppUnitTestFramework通过创建自定义TestEventListener。然后，我创建了一组简单的接口函数，以使其更易于使用。
我用的是gmock 1.7.0 NuGet 包将 GMock 框架安装到我的项目中，并添加如下所示的两个文件。
GMockUtils.h
#pragma once
#include <CppUnitTest.h>
#include <gmock/gmock.h>
namespace testing {
namespace GMockUtils {
// Call once per test class or module to set up everything needed by GoogleMock.
void InitGoogleMock();
// Call once per test method to check for GoogleMock messages.
void CheckGoogleMock();
}
}
GMockUtils.cpp
#include "stdafx.h"
#include "GMockUtils.h"
using namespace Microsoft::VisualStudio::CppUnitTestFramework;
namespace testing {
namespace GMockUtils {
namespace {
// Test event listener for use with CppUnitTestFramework
class CppUnitTestReporter : public EmptyTestEventListener
{
public:
CppUnitTestReporter() : _failed(false)
{
}
// Helper for converting std::string to std::wstring
std::wstring to_wstring(const std::string& str) const
{
std::wstring output;
std::copy(str.begin(), str.end(), std::back_inserter(output));
return output;
}
// Called after a failed assertion or a SUCCEED() invocation.
void OnTestPartResult(const ::testing::TestPartResult& result) override
{
// Log this result to the CppUnitTestFramework output
Logger::WriteMessage(result.summary());
// Note: You cannot do an Assert directly from a listener, so we
// just store the messages until CheckGoogleMock() is called.
if (result.failed())
{
_failed = true;
// Append this result to the running summary
_failedSummary += result.message();
_failedSummary += "\n";
}
}
// Clear any previous failures
void ResetFailures()
{
_failed = false;
_failedSummary.clear();
}
// Assert if any failures have been detected. Also resets failures.
void CheckFailures()
{
auto failed = _failed;
auto failedSummary = _failedSummary;
ResetFailures();
Assert::IsFalse(failed, to_wstring(failedSummary).c_str());
}
protected:
bool _failed;
std::string _failedSummary;
} *_listener;
}
// Initialize the Google Mock framework for use with CppUnitTestFramework
void InitGoogleMock()
{
// Avoids calling the function unnecessarily
if (_listener != nullptr)
return;
// Dummy command line parameters (could pass exe path here)
int argc = 0;
char** argv = nullptr;
// Initialize the framework
::testing::InitGoogleMock(&argc, argv);
// We don't want exceptions thrown, regardless what the doc says
GTEST_FLAG(throw_on_failure) = false;
// Remove default listener
auto &listeners = UnitTest::GetInstance()->listeners();
delete listeners.Release(listeners.default_result_printer());
// Create and install the new listener
_listener = new CppUnitTestReporter();
listeners.Append(_listener);
}
// Reset any previous failures detected by the listener
void ResetGoogleMock()
{
_listener->ResetFailures();
}
// Prints messages and asserts if any Google Mock messages are found.
void CheckGoogleMock()
{
Assert::IsNotNull(_listener, L"Google Mock framework not initialized by InitGoogleMock()");
_listener->CheckFailures();
}
}
}
我在单元测试类中使用 GMockUtils 函数，如下所示：
#include "GMockUtils.h"
using namespace Microsoft::VisualStudio::CppUnitTestFramework;
using namespace ::testing;
namespace GMockUtilsDemo
{
TEST_CLASS(GMockUtilTests)
{
public:
TEST_CLASS_INITIALIZE(ClassInitializer)
{
// IMPORTANT: This must be called before any mock object constructors
GMockUtils::InitGoogleMock();
}
TEST_METHOD_CLEANUP(MethodCleanup)
{
// Checks for GoogleMock messages. Asserts if found.
GMockUtils::CheckGoogleMock();
}
TEST_METHOD(Method1_ParamIsOne_Method2CalledWithOne)
{
MockTestClass mockObj;
EXPECT_CALL(mockObj, Method2(1)).Times(1); // Expectation will be met
mockObj.Method1(1);
}
TEST_METHOD(Method1_ParamIsZero_IntentionallyFail)
{
MockTestClass mockObj;
EXPECT_CALL(mockObj, Method2(1)).Times(1); // Expectation will not be met
mockObj.Method1(0);
}
};
}
控制台输出
控制台输出现在显示所有 GMock 消息，并且运行不会在第一次测试失败时中止。
[3/27/2019 12:23:46 PM Informational] ------ Run test started ------
[3/27/2019 12:23:46 PM Informational]
Unexpected mock function call - returning directly.
Function call: Method2(0)
Google Mock tried the following 1 expectation, but it didn't match:
c:\...\gmockutilsdemo.cpp(64): EXPECT_CALL(_mockObj, Method2(1))...
Expected arg #0: is equal to 1
Actual: 0
Expected: to be called once
Actual: never called - unsatisfied and active
[3/27/2019 12:23:46 PM Informational] Actual function call count doesn't match EXPECT_CALL(_mockObj, Method2(1))...
Expected: to be called once
Actual: never called - unsatisfied and active
[3/27/2019 12:23:46 PM Informational] ========== Run test finished: 2 run (0:00:00.8631468) ==========
测试资源管理器视图
如果我通过 Visual Studio 测试资源管理器运行测试，我还可以看到与特定测试相关的所有 GMock 消息。它还可以与 Azure DevOps 上的 VsTest 任务配合使用。
希望这对任何遇到同样情况的人都有用。