Mocking internal calls of a function being tested using googlemock

Question

I am new to Google Mock and based on my understanding of the documentation and online resources, I could not identify a solution to my problem:

I have the following classes:

class A
{
    public:
        A() { }
        int fun1()
        {
            //Some code
            B b;
            x = b.fun2();
            //Some other code
        }
};
class B
{
    public:
        B() { }
        int fun2()
        {
            //Some code
            y = C::fun3();
            //Some code
        }
};
class C
{
    public:
        static int fun3()
        {
            //Read a file and provide success if a certain pattern is found
        }
};

Now I am trying to write a Google test for A::fun1(). But because of the structure of the code (all the calls are through objects and I do not have a base class using which I can initialize a mock etc., I am not able to mock this successfully.

Can someone help me understand if this is mockable with Google Mock in its current form? Please note that I am not allowed to change the original source code.

Answer 1

You can only do this as long the class under test can be configured using static interfaces (ie template parameters). See here for more information: Mocking Nonvirtual Methods .

Another alternative may be to introduce wrapper interfaces in your class under test, that can be mocked as usual: Alternative to Mocking Concrete Classes .

If you can't change any of the code it's not possible IMHO.

UPDATE : As long class B is instantiated inside A::fun1() , it will be hard to mock B anyway. It should be passed as parameter, thus you have a chance to control the instantiation in your test method.

May be a viable solution for you could be to spoof the build environment for testing, and provide a declaration and definition for class B that provides a mock.