Pythonic tests with Py.test

Talk presented at Geek Night Recife @ ThoughtWorks

Transcript

1. Pythonic tests with py.test Renato Oliveira
2. Who?! ❏ Renato Oliveira ❏ Labcodes Software Studio ❏ Django Software Foundation ❏ Recently migrated to Py.test
3. Sumary ❏ Introduction ❏ Basic Usage ❏ Test discovery ❏ Markers ❏ Fixtures ❏ Plugins
4. FIX IN PROD
5. Tests in prod
6. Tests in prod
7. Introduction “Pytest is a mature full featured Python testing tool that helps you to write better programs.”
8. Introduction - Assert with assert statement def sum(a, b): return a + b def test_sum(): assert sum(1, 1) == 2
9. Basic usage - Running - Failure report
10. Test discovery and runner Simply run your tests with $ py.test
11. Test discovery and runner Verbosely $ py.test -v
12. Test discovery and runner Pytest recursively searches your folders looking for test files test_*.py or *_test.py
13. Test discovery and runner You can test just a file $ py.test test_foo.py
14. Test discovery and runner You can also execute just one test $ py.test -k test_foo
15. Migrating Unittest code Code before import unittest def to_upper(text): return text.upper() class TestToUpper(unittest.TestCase): def test_to_upper(self): self.assertEqual(to_upper("pug"), "PUG")
16. Migrating Unittest code Code after def to_upper(text): return text.upper() def test_to_upper(): return to_upper("pug") == "PUG"
17. Markers Gives you the ability to add some extra metadata to your tests. ❏ skipif ❏ xfail ❏ parametrize ❏ your owns
18. skipif @pytest.mark.skipif(sys.version_info < (3, 3), reason="requires python3.3") def test_function(): assert 1 == 1
19. xfail @pytest.mark.xfail(reason="1 is not 2") def test_fail(): assert 1 == 2
20. parametrize @pytest.mark.parametrize("input,expected", [ ("3+5", 8), ("2+4", 6), pytest.mark.xfail(("6*9", 42)), ]) def test_eval(input, expected): assert eval(input) == expected
21. slow test, fast test @pytest.mark.slow def test_slow(): assert 1 == 1 @pytest.mark.fast def test_fast(): assert 1 == 1
22. Fixtures The purpose of test fixtures is to provide a fixed baseline upon which tests can reliably and repeatedly execute.
23. Fixtures Pytest fixtures allows you to decouple your test suite from the context you want them to run.
24. Fixtures @pytest.fixture() def answer(): return 42 def test_the_ultimate_question_about_life_the_universe_and_everything(answer): assert answer == 42
25. @pytest.fixture() def webdriver(request): driver = Firefox() request.addfinalizer(driver.quit) return driver def test_pug_website_title(webdriver): webdriver.get("http://pycon.pug.pe/XXXVIII/") assert "Encontro do PUG-PE" in webdriver.title def test_python_website_title(webdriver): webdriver.get("http://python.org/") assert "Python" in webdriver.title
26. Share fixtures - pytest.mark.usefixtures - conftest.py - “usefixtures” param in pytest.ini
27. Useful plugins - pytest-django - pytest-mock - http://pytest. org/latest/plugins_index/index.html
28. Questions?
29. Obrigado! :) renato@labcodes.com.br @_renatooliveira github/renatooliveira www.labcodes.com.br