Python comes with a very easy-to-use unittest library built in. Write a simple function that accepts two numbers, and returns True if the first number is evenly divisible by the second.

def divisible_by(check_number, divisor):
    return check_number % divisor == 0

Save your file as In a second file called, create a TestCase using the unittest framework and use asserts to verify that the divisible_by()function returns the correct result. Don’t forget to import your divisible_by() function.

import unittest
from divisible import divisible_by

class TestCase(unittest.TestCase):

    def test_divisible_by(self):
        self.assertTrue(divisible_by(10, 2))
        self.assertTrue(divisible_by(10, 3))

if __name__ == '__main__':

Name your file and run it:

(env) $ python --verbose
Here's what you should have seen on your command line:

You should have gotten an error: AssertionError: False is not true caused by self.assertTrue(divisible_by(10, 3)). Makes sense, because 10 is not evenly divisible by 3.

Change self.assertTrue to self.assertFalse and your test should pass.

(env) $ python --verbose
test_divisible_by (__main__.TestCase) ... ok

Ran 1 test in 0.000s