Simple powerful testing with py.test

Talk at Django usergroup Berlin about py.test

Transcript

1. PY.TEST SIMPLE POWERFUL TESTING WITH PYTHON ANDREAS HUG
2. ABOUT • test framework • created by Holger Krekel et al. • used by PyPy
3. FEATURES • assert statements • auto-discovery • modular fixtures • multi-paradigm support (unittest, nose) • markers • easy configuration • plugins
4. ASSERT • standard assert instead of assertXXX • assert that exceptions are raised assert x == 1 assert x != 1 assert x in [1, 2, 3] assert x < 5 pytest.raises(ZeroDivisionError, lambda x: 1 / x, 0) with pytest.raises(ZeroDivisionError): 1 / 0
5. ASSERT • descriptive feedback def test_x(): > assert sum(range(3)) == 4 E assert 3 == 4 E + where 3 = sum([0, 1, 2]) E + where [0, 1, 2] = range(3) def test_list(): > assert [1, 2, 3] == [1, 2] E assert [1, 2, 3] == [1, 2] E Left contains more items, first extra item: 3 def test_long(): a = '-'*50 + 'a' + '-'*50 b = '-'*50 + 'b' + '-'*50 > assert a == b E assert '--------...---------' == '---------...---------' E Skipping 44 identical leading characters in diff E Skipping 45 identical trailing characters in diff E - ----------a--------- E ? ^ E + ----------b--------- E ? ^
6. AUTO-DISCOVERY • single file by path • multiple files by recursive detection • specific packages with --pyargs !"" foopackage # !"" foomodule.py # $"" tests # $"" test_foomodule.py $"" tests $"" test_foomodule.py $ py.test $ py.test foopackage/tests/ $ py.test foopackage/tests/test_foomodule.py $ py.test --pyargs foopackage
7. AUTO-DISCOVERY • all functions and methods prefixed with test_ • all classes prefixed with Test • specific functions or classes with -k from foopackage import foomodule def test_add(): assert foomodule.add(1, 2) == 3 class TestFoo(object): def test_negative(self): assert foomodule.add(1, -1) == 0 $ py.test -k "TestFoo and test_negative"
8. FIXTURES • sets up objects or apps for testing • used via dependency injection import pytest @pytest.fixture def foo(): return 'foo' def test_something(foo): assert foo == 'bar'
9. FIXTURES • function, class module and session scope import pytest @pytest.fixture(scope='module') def foo(): time.sleep(2) return 'foo' def test_something(foo): assert foo == 'bar' def test_something_else(foo): assert foo == 'baz'
10. FIXTURES • function, class module and session scope import pytest @pytest.fixture() def foo(): pass @pytest.mark.usefixtures('foo') class TestClass(object): def test_something(self): assert 1 == 1 def test_something_else(self): assert 2 == 2
11. FIXTURES • function, class module and session scope import pytest class TestClass(object): @pytest.fixture(autouse=True) def foo(self): pass def test_something(self): assert 1 == 1 def test_something_else(self): assert 2 == 2
12. FIXTURES • finalizer @pytest.fixture def foo(request): # create something def clean_up(): # destroy something request.addfinalizer(clean_up)
13. FIXTURES • parametrization of fixtures and test functions import pytest @pytest.mark.parametrize(('foo', 'bar'), [(1, 2), (1, 3)]) def test_with_parameters(foo, bar): assert foo == bar import pytest @pytest.fixture(params=[1, 2]) def foo(request): return request.param def test_something(foo): assert foo == 3
14. MULTI-PARADIGM SUPPORT • supports unittest and nose style tests from unittest import TestCase class TestUser(TestCase): @classmethod def setUpClass(cls): cls.foo = 1 def setUp(self): self.bar = 2 def test_something(self): assert self.foo == self.bar
15. MARKERS • supports unittest and nose style tests import pytest @pytest.mark.slowtest def test_something(): assert 1 $ py.test -m slowtest
16. EASY CONFIGURATION • project config file: pytest.ini • per directory configuration: conftest.py
17. PLUGINS • several plugins available: • pytest-twisted • pytest-capturelog • pytest-xdist • pytest-timeout • pytest-cache • pytest-cov • pytest-pep8
18. PLUGINS • easy to write custom plugins def pytest_addoption(parser): """Define additional commandline options""" group = parser.getgroup('fooplugin') group.addoption('--foo', action='store_true', default=False) def pytest_configure(config): """Activate plugin if according option is set""" if config.getvalue('active'): config.pluginmanager.register(FooPlugin()) class FooPlugin(object): def pytest_sessionstart(self, session): pass def pytest_sessionfinish(self, session, exitstatus): pass
19. Does it work with ???????
20. DJANGO • pytest-django • pytest plugin • django-pytest • django testrunner
21. PYTEST-XDIST • multiprocess load-balancing • multi-platform coverage • works with django (kind of)
22. THX
23. Moccu GmbH & Co. KG Kreativagentur für digitale Medien Pappelallee 10 10437 Berlin Tel: +49 (0)30 - 44 01 30 - 30 Fax: +49 (0)30 - 44 01 30 - 50 E-Mail: info@moccu.com Web: www.moccu.com Facebook: facebook.com/moccu Twitter: moccu Youtube: youtube.com/moccu Willkommen! KONTAKT