examples/pytest/test_fibonacci_ok.py
import mymath

def test_fibonacci():
    assert mymath.fibonacci(1) == 1

examples/pytest/test_fibonacci_ok.out
$ py.test test_fibonacci_ok.py
============================= test session starts ==============================
platform darwin -- Python 2.7.5 -- py-1.4.20 -- pytest-2.5.2
collected 1 items

test_fibonacci_ok.py .

=========================== 1 passed in 0.01 seconds ===========================