Unit testing of private methods

Question

I am in the process of writing some unit tests. In particular I want to test some private methods.

So far the I have come up with using.

#define private public

But I am not happy with this as it will destroy all encapsulation from the point of view of the unit test.

What methods do you use to unit-test private methods.

user_6426649 · Answer

After many hours this is what I decided to be the best solution for ones that want to test their private functions. This is combination of answers by Max DeLiso and Miloš.

If you are using boost::unit-test then there's an easy and elegant solution.

Use protected instead of private in your classes

/* MyClass.hpp */

class MyClass {

protected:
    int test() {
        return 1;
    }
};

Create a fixture:

/* TestMyClass.cpp */

class F : public MyClass {};


BOOST_FIXTURE_TEST_SUITE(SomeTests, F)

// use any protected methods inside your tests
BOOST_AUTO_TEST_CASE(init_test)
{
    BOOST_CHECK_EQUAL( test(), 1 );
}
BOOST_AUTO_TEST_SUITE_END()

This way you can freely use any of the MyClass functions without #define private public or adding friends to you class!

Unit testing of private methods

8 Answers