See Getting started with testing in Python on RealPython

  • Unittest
    • Python builtin.
  • PyTest
    • Python package.
    • Great for getting into testing. Uses functions.
    • Uses its own form of tests.
  • Nose
    • Python package.
    • Uses unittest-style tests.
    • More advanced than PyTest and it recommends PyTest for starting out.

Unittest

Syntax

  • Create a class which inherits from unittest.TestCase.
  • Add methods that start with test_*.
  • Add a call in the __main__ check which runs unittest.main().

Sample tests

# test_string_methods.py
import unittest


class TestStringMethods(unittest.TestCase):

    def test_upper(self):
        self.assertEqual('foo'.upper(), 'FOO')

    def test_isupper(self):
        self.assertTrue('FOO'.isupper())
        self.assertFalse('Foo'.isupper())

    def test_split(self):
        s = 'hello world'
        self.assertEqual(s.split(), ['hello', 'world'])
        # check that s.split fails when the separator is not a string
        with self.assertRaises(TypeError):
            s.split(2)


if __name__ == '__main__':
    unittest.main()

# test_sum.py
import unittest


class TestSum(unittest.TestCase):

    def test_sum(self):
        self.assertEqual(sum([1, 2, 3]), 6, "Should be 6")

    def test_sum_tuple(self):
        self.assertEqual(sum((1, 2, 2)), 6, "Should be 6")


if __name__ == '__main__':
    unittest.main()

Run

Run against a directory (module) with verbose flag.

python -m unittest -v test

Scan for test*.py files.

python -m unittest discover

Use -sand the name of a directory.

python -m unittest discover -s tests

Change to the src/ directory, scan for all test*.py files inside the the tests directory, and execute them.

python -m unittest discover -s tests -t src

PyTest

Install

$ pip install pytest

Sample test

Define a function starting with test_*.

# test_sample.py
def inc(x):
    return x + 1

def test_answer():
    assert inc(3) == 5

Run tests

Run all test suits:

$ pytest

Run targets - see Usage docs.

$ # Module
$ pytest test_abc.py
$ # Directory
$ pytest dir_name/
$ # Keyword. Exclude keywords.
$ pytest -k "MyClass and not method"

Run only failed tests:

$ pytest --last-failed

Run in parallel e.g. with 4 processes:

$ pytest -n 4

Run quietly - taken from PyCharm:

$ pytest --no-header --no-summary -q

Nose

Install

$ pip install nose

Run tests

$ nosetests