c++ - 如何在内联回调函数中使用 EXPECT_EQ 和其他 Google Mock 语句？

Question

假设我有这个测试用例:

TEST_F(TestCase1, HappyCase){
    foo->doSomething(arg1, new inlineCallback([=](bool success){
        EXPECT_EQ(success, true);
    }));
}

但是:

EXPECT_EQ(success, true)

只会在您实际调用 inlineCallback 并在 foo 类的 doSomething 函数的实现中传递一个 bool 值时被调用。

但也可能是实现非常复杂，并且有可能永远不会调用 inlineCallback，那么 EXPECT_EQ(success, true) 将不会被调用，这个测试用例几乎没有用。

我如何始终确保 EXPECT_EQ(success, true) 始终得到评估？

Answer 1

一个简单的方法是通过引用捕获一个 bool 值并在回调中将其设置为 true:

TEST_F(TestCase1, HappyCase) {
    bool callback_called = false;

    foo->doSomething(arg1, new inlineCallback([&callback_called, =](bool success) {
        callback_called = true;
        EXPECT_TRUE(success);
    }

    EXPECT_TRUE(callback_called);
}

如果你的回调都有一个共同的(抽象的)基类，它们继承自(inlineCallback 类的存在强烈暗示)，那么你也可以改用 Googlemock 及其参数匹配器:

// assuming this is the callback interface
class Callback {
public:
     Callback() = default;
     Callback(Callback const&) = delete;
     Callback(Callback&&) = delete;
     Callback& operator=(Callback const&) = delete;
     Callback& operator=(Callback&&) = delete;
     virtual ~Callback() = default;

     virtual void operator()(bool) = 0;
};

class MockCallback : public Callback {
public:
    // since Googlemock can't mock operators directly we add one level 
    // of indirection
    MOCK_METHOD1(calledWith, void(bool));

    void operator()(bool const arg) override { 
      calledWith(arg);
    }
};

TEST_F(TestCase1, HappyCase) {
    auto callback = std::make_unique<::testing::StrictMock<MockCallback>>();

    EXPECT_CALL(*callback, calledWith(true));

    foo->doSomething(arg1, callback.release());
}