Why the g-mocked method is not called in my code

Question

I am trying to implement a mock method and verify that the same is only called. Below is a simple example where I am trying to mock Class A:ShowPubA2 method. Hence I have the below code:

class A {
public:
    virtual void ShowPubA1()
    {
        std::cout << "A::PUBLIC::SHOW..1" << std::endl;
    }
    virtual int ShowPubA2(int x)
    {
        std::cout << "A::PUBLIC::SHOW..2 " << x << std::endl;
        return x;
    }
};

class MockA : public A {
public:
    MOCK_METHOD0(ShowPubA1, void());
    MOCK_METHOD1(ShowPubA2, int(int x));
};

Now I declare another class B inheriting from A -

class B : public A
{
public:
    int ShowPubB2(int x)
    {
        ShowPubA2(x);
        std::cout << "B::PUBLIC::SHOW..2 " << x << std::endl;
        return x;
    }
};

Below is my TEST case details:

TEST(FirstB, TestCall) {
    using ::testing::_;
    MockA a;
    EXPECT_CALL(a, ShowPubA2(_)).Times(AtLeast(1));
    B b;
    EXPECT_EQ(2, b.ShowPubB2(2));
}

From the output we can see that the actual implementation is called and not the mock methods - hence the test fails:

[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from Firstb
[ RUN      ] Firstb.TestCall
A::PUBLIC::SHOW..2 2
B::PUBLIC::SHOW..2 2
c:\myuser\documents\c and c++\gmock\consoleapplication1\consoleapplicati
n1\consoleapplication1.cpp(69): error: Actual function call count doesn't match
EXPECT_CALL(a, ShowPubA2(_))...
         Expected: to be called at least once
           Actual: never called - unsatisfied and active
[  FAILED  ] Firstb.TestCall (0 ms)
[----------] 1 test from Firstb (0 ms total)

[----------] Global test environment tear-down
[==========] 1 test from 1 test case ran. (0 ms total)
[  PASSED  ] 0 tests.
[  FAILED  ] 1 test, listed below:
[  FAILED  ] Firstb.TestCall

 1 FAILED TEST
Press any key to continue . . .

Please let me know how can I mock a method and called upon in place of its actual.

Answer 1

You should change B to inject A to something like:

class B
{
public:
    explicit B(A& a) : a(&a) {}

    int ShowPubB2(int x)
    {
        a->ShowPubA2(x);
        std::cout << "B::PUBLIC::SHOW..2 " << x << std::endl;
        return x;
    }
private:
    A* a;
};

and then

TEST(FirstB, TestCall) {
    using ::testing::_;
    MockA a;
    EXPECT_CALL(a, ShowPubA2(_)).Times(AtLeast(1));
    B b(a);
    EXPECT_EQ(2, b.ShowPubB2(2));
}