A sample test has been added.

A reflection is its own inverse. Performing the reflection twice returns every point to its original position.

And to answer to your last question: No, there are no bonus points here. The tests don't analyze your code; they just control your answer (I think this would just be practically impossible).

This kata is old, has been solved a huge amount of times, and changing its design in the sense of your suggestion would invalidate most of the submitted solutions, and actually would make it a completely different kata. This is not going to happen. Howerver, there exists a good amount of more challenging katas relative to arithmetics and divisibility for those who are interested in it..