Black Box Testing
If you test a software for its functionality without worrying about the internal structure of the software, then you are performing Black Box Testing.. Internal structure of a software may be its actual code, comments, whether a variable has been declared but not used etc.
In this Black Box Testing approach you would be just testing the functionality of the software by giving input and verifying its result ( referred as Test Result).
All you have to do is to ensure that each feature and/or functionality is tested with appropriate data(sets).