Why pytest?

Pytest is a mature and full-featured testing framework, from small tests to large scale functional tests for applications and libraries alike.

Pytest is simple to get started with. To write tests, you don't need classes; you can write simple functions that start with test and use Python's built-in assert statement:

    from fibo import fibonacci

    def test_fibo():
        assert fibonacci(4) == 3

That's it. You import your code, write a function, and use plain assert calls to ensure they are working as you expect: no need to make a subclass and use various self.assert* methods to do your testing. And the beautiful thing is that it also provides helpful output when an assertion fails:

    λ pytest test_fibo2.py -q
    F                                                              [100%]
    ============================= FAILURES ==============================
    _____________________________ test_fibo _____________________________

        def test_fibo():
    >       assert...