如何使用 gtest 模拟 EXPECT_CALL

Question

In the code below I tried to explain my problem on a basic model.

class A
{
    public:
    A() {}
    virtual void foo() {}
    virtual ~A(){}
    //...
};
    

class B : public A{
    public:
    B(){}
    //...
    //does not contain the override function foo() 
};

class MustBeTested{
    public:
    MustBeTested(){
        //...    
    }
    void function()
    {
        m_elem->foo();
        //...
    }
    
    private:
    B* m_elem;
};


class Mock : public B {
    public:
    Mock() {}
    MOCK0(foo, void());
};

//test function from above class
void TestFunction
{
    Mock* dummy = new Mock;
    EXPECT_CALL(*dummy, foo()).Times(1);
    //i know it is wrong becase the called method is A::foo();
}


    

I have a basic class A that contains a virtual method. Derivative class B no longer contains the overwritten method foo (). The MustBeTested class contains the function to be tested, the class member is type B *. Initially without looking I started to make a Mock class derived from B to simulate EXPECT_CALL (). I realized that it is not possible because the method in A :: foo () will always be called.

My question is, if there is a workaround without making changes to the class A or B code?

Answer 1

foo in B is not overriden, but it is there - with the default implementation from A . foo is virtual and can be overriden in classes that derive from B , like your Mock (that wouldn't be possible if foo was marked final in B ). Your code will work if you will use dependency injection in MustBeTested , see Dependency injection with unique_ptr to mock .