I don't usually feel the need to unit test private members and functions. I might prefer to introduce a public function just to verify correct internal state.
But if I do decide to go poking around in the details, I use a nasty quick hack in the unit test program:
#include
#include
// Include ALL system headers that test-class-header might include.
// Since this is an invasive unit test that is fiddling with internal detail
// that it probably should not, this is not a hardship.
#define private public
#include "test-class-header.hpp"
...
On Linux at least this works because the C++ name mangling does not include the private/public state. I am told that on other systems this may not be true and it wouldn't link.
