Mock a conversion operator int() using google mock

Question

I have a class with following operator declared:

Foo::operator int() const
{
    return m_bar; // a private variable with type int of the class Foo
}

I want to mock class Foo but I have difficulties on this one. I looked up online and saw no solutions for conversion operators like int() in this case. Could anyone help please? Thank you.

Answer 1

I'm not sure if there's a way to mock the conversion operator directly, but something along these lines would work:

class MockFoo : public Foo {
public:
    MOCK_CONST_METHOD0(conversionOperator, int());

    virtual operator int() const { return conversionOperator(); }
};

This would be used as you expect:

TEST(ConversionOperator, Returns42) {

    MockFoo f;
    EXPECT_CALL(f, conversionOperator()).WillOnce(Return(42));

    int value = f;
    ASSERT_EQ(42, value);
}