Add Unit tests

[jaggbow]

I usually find myself testing by hand on a crappy notebook that a functions behaves the way it's intended. Unit tests should bring not only a sense of certainty about an implementation but will also save time for others who want to verify if something works.

I don't have much experience with this however, who's down to help?

PS: I assigned all of you to get notified but don't feel obliged to contribute to this issue if you don't want to !

[josephdviviano]

Would love to help!

[jaggbow]

Look at #11 if you want to add unit tests.