An example of testing in python

fib.py

def fib (a, b, max ):
	while (b < max):
		tmp = a
		a = b
		b = a + b
	return b

fib_test.py

# To install a test runner, $ pip install trial
# To run this test, $ trial fib_test.py
import unittest
from fib import fib

class TestFib(unittest.TestCase):
    def test_fib(self):
        self.assertEqual(fib(1, 1, 2), 2)
        self.assertEqual(fib(1, 1, 5), 5)
        self.assertEqual(fib(1, 1, 7), 8)