22 Unit Testing¶

by Professor Ray Toal Loyala Marymount
October 22, 2011

How to unit test¶

Not manually
You wrote code that exercises your code
Perform assertions that record
- That you get the results you expect

# TODO - get more info

Test Driven Development¶

Write some tests
Run them
- They’ll fail cause you have no code
Write some code
Now run the tests again
Work until the tests pass
Iterate!

Unit testing in Python¶

Uses the module unittest is already there
Docs
- Python 2.7
- Python 3 (http://python.readthedocs.org/en/latest/library/unittest.html)

First example¶

Interleave two lists:

interleave([], [])
interleave([1,2,3], [1,2,3,4,5])
interleave([1,2,3], ["hello, world",])

Test code:

# test_interleave.py
from interleave import interleave
import unittest

class TestGettingStarted(unittest.TestCase):
    def test_interleave(self):
        cases = [
            ([],[],[]),
            ([1,2,3], [1,2,3,4,5]),
            ([1,2,3], ["hello, world",])
        ]
        for case in cases:
            self.assertEqual(interleave(case[0], case[1], case[2]))

# interleave.py
def interleave(a, b):
    # will fail. Fix
    return [x for x in izip_longest(a, b) for y in x if y is not None]