How to mock method with optional parameter in Google Mock?

Question

How to mock a method with optional parameter in Google Mock? For example:

class A
{ 
public:
    void set_enable( bool enabled = true );
};

class MockA : public A
{
    MOCK_METHOD1( set_enable, void( bool ) );    // this is not working
};

Answer 1

This is an alternative of Marko's answer: If you don't want to change your original code, just implement the helper in the mock class:

class A
{ 
public:
    virtual void set_enable( bool enabled = true );
};

class MockA : public A
{
    MOCK_METHOD1( set_enable_impl, void( bool ) );
    virtual void set_enable( bool enabled = true )
    {
        set_enable_impl( enabled );
    }
};

You still have to expect calls of set_enable_impl in your tests, for example

MockA mockA;
EXPECT_CALL(mockA, set_enable_impl(true)).Times(Exactly(1));
EXPECT_CALL(mockA, set_enable_impl(false)).Times(Exactly(1));

Answer 2

Change implementation of your method set_enable to use a helper method, like this:

void set_enable( bool enabled = true ) { set_enable_impl(enabled); }

Now, in class MockA, create a mock method for set_enable_impl:

MOCK_METHOD1( set_enable_impl, void( bool ) );

Then, in your production code you simply use set_enable as you would in the first place, while in tests you can set expectations on method set_enable_impl:

MockA mockA;
EXPECT_CALL(mockA, set_enable_impl(_))...;

An alternative would be to overload the method by having versions with one and zero parameters. It is up to you to determine which way works better for your case.