C++,Googlemock - 测试本地对象

Question

我开始使用googletest和googlemock库,我遇到了一个无法解决的问题.我有一个像这样的代码:

class Painter
{
  public:
  void DrawSomething();
};

void Painter::DrawSomething()
{
  Turtle turtle;
 turtle.doSomething();
}

main()
{
  Painter p;
  p.DrawSomething();
}

我已经模拟了Turtle类,但是如果在本地创建了turtle对象,我该如何测试doSomething()方法(例如使用EXPECT_CALL)？是否可以不修改Painter类？

谢谢你的回答.

Answer 1

我嘲笑了海龟课...

您究竟如何嘲笑它？

...但是当本地创建turtle对象时，如何测试doSomething()方法（例如使用EXPECT_CALL）？ 是否可以不修改Painter类？
_{（强调我的）}

直接的答案是：不。

如果不通过接口进行解耦，则无法神奇地注入模拟而不是其他类中使用的真实实例。

您应该具有类似以下代码的内容：

struct ITurtle {
    virtual void PenUp() = 0;
    virtual void PenDown() = 0;
    virtual void TurnLeft(double degrees) = 0;
    virtual void Move(double distance) = 0;
    // ...
    virtual ~ITurtle() {}
};

struct TurtleMock : ITurtle {
    // Mock method declarations
    MOCK_METHOD0(PenUp, void ());
    MOCK_METHOD0(PenDown, void ());
    MOCK_METHOD1(TurnLeft, void (double));
    MOCK_METHOD1(Move, void (double));
};

class Turtle : public ITurtle {
public:
    void PenUp();
    void PenDown();
    void TurnLeft(double degrees);
    void Move(double distance);
};

在单独的翻译单元中提供上述声明的实际实现。

class Painter {
public:
    Painter(ITurtle& turtle) : turtle_(turtle) {}   
    void DrawSomething();
private:
    ITurtle& turtle_;
};

void Painter::DrawSomething() {
    turtle_.PenDown();
    turtle_.TurnLeft(30.0);
    turtle_.Move(10.0);
    turtle_.TurnLeft(30.0);
    turtle_.Move(10.0);
    // ...
}

您也可以将ITurtle接口传递给DrawSomething()函数：

class Painter {
public:
    void DrawSomething(ITurtle& turtle);
};

void Painter::DrawSomething(ITurtle& turtle) {
    turtle.PenDown();
    turtle.TurnLeft(30.0);
    turtle.Move(10.0);
    turtle.TurnLeft(30.0);
    turtle.Move(10.0);
    // ...
}

int main() {
     NiceMock<TurtleMock> turtle;
     Painter p(turtle);
     // Painter p; <<< for the alternative solution

     EXPECT_CALL(turtle,PenDown())
         .Times(1);
     EXPECT_CALL(turtle,TurnLeft(_))
         .Times(2);
     EXPECT_CALL(turtle,Move(_))
         .Times(2);

     p.DrawSomething();
     //  p.DrawSomething(turtle); <<< for the alternative solution

}