examples/pytest/mymath.py
def fibonacci(n):
    if n==1:
        return 1
    if n==2:
        return 1
    if n==3:
        return 5

    return 'unimplemented'

def fibo(n):
    if n == 1:
        return [1]
    if n == 2:
        return [1, 1]
    if n == 3:
        return [1, 1, 5]
    raise Exception('unimplemented')

def test_selfie():
    assert fibonacci(1) == 1
    assert fibonacci(2) == 1
    #assert fibonacci(3) == 2

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

mymath.py .

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