Writing unit tests in Python: How do I start?

Question

I completed my first proper project in Python and now my task is to write tests for it.

Since this is the first time I did a project, this is the first time I would be writing tests for it.

The question is, how do I start? I have absolutely no idea. Can anyone point me to some documentation/ tutorial/ link/ book that I can use to start with writing tests (and I guess unit testing in particular)

Any advice will be welcomed on this topic.

Answer 1

If you're brand new to using unittests, the simplest approach to learn is often the best. On that basis along I recommend using py.test rather than the default unittest module.

Consider these two examples, which do the same thing:

Example 1 (unittest):

import unittest

class LearningCase(unittest.TestCase):
    def test_starting_out(self):
        self.assertEqual(1, 1)

def main():
    unittest.main()

if __name__ == "__main__":
    main()

Example 2 (pytest):

def test_starting_out():
    assert 1 == 1

Assuming that both files are named test_unittesting.py, how do we run the tests?

Example 1 (unittest):

cd /path/to/dir/
python test_unittesting.py

Example 2 (pytest):

cd /path/to/dir/
py.test