you've created a testing tautology that essentially tests if True == True.  You've mocked the function that you want to test, so you end up testing the mock rather than the method to be tested. 

Since in the ```get_raw_crash``` in this class is a forwarding function, it is ok to mock the object to which the execution is forwarded:

    db_sampling._implementation = mock.Mock()
    db_sampling._implementation.get_raw_crash = mocked_get_raw_crash