Modernize test suite

[deeplook]

Modernize test suite

[claudep]

I know some prefer pytest over unittest, but I'd like to know the advantages in this particular lib. That's a real question, not a rant of some sort!

[deeplook]

Pytest uses no boilerplate code, is more flexible and more Pythonic. It reports differences between received and expected structured results on deeper levels. It is easier to use when testing for raised or upraised exceptions (if I remember correctly). And it's a project that sees continuous improvements unlike anything in the unittest world. And there are surely more reasons I don't remember now.

[claudep]

Thanks for developing your arguments. I think I'll still need to see real examples to be convinced, but anyway, it's not a blocker for my contributions at all.