Pytest
- Assertions
- Conditional tests
- Within-test control flow
- Fixtures
Assertions
| What | How | Details |
| Assert warning | with pytest.warns(UserWarning): | |
| Assert any error | with pytest.raises(Exception) as excinfo: | |
| Assert specific exception e | with pytest.raises(e) as excinfo: | |
| Assert either exception e1 or e2 | with pytest.raises((e1, e2)): | |
Conditional tests
| What | How | Details |
| Skip test | @pytest.mark.skip(reason="no way to currently test this") | |
| Conditional skip | @pytest.mark.skipif(cond, reason) | |
| Skip for Python version below x.y | @pytest.mark.skipif(sys.version_info < (x, y)) | |
| Skip if on Windows | @pytest.mark.skipif(sys.platform == 'win32') | |
| Skip if module is missing | @pytest.importorskip('pandas') | |
| Expect test to fail | @pytest.mark.xfail() | |
| Expect test to fail with exception e | @pytest.mark.xfail(raises=e) | |
| Fail test if not completed within n seconds | @pytest.mark.timeout(n) | |
| Fail test on Windows | @pytest.mark.xfail(sys.platform == 'win32') | |
| Parameterize test for argument x | @pytest.mark.parametrize('x', [1, 2, 3]) | |
| Parameterize test for multiple arguments | @pytest.mark.parametrize('length', [1, 2, 3])
@pytest.mark.parametrize('value', [0, 1]) | |
| Parameterize for combination of arguments | @pytest.mark.parametrize('length,value', [(1, 0), (2, 1), (3, 1)]) | |
| Parameterize using parameterized fixture | @pytest.mark.parametrize('large_dynamic_data_file', ['big.csv', 'big2.csv'], indirect=True) | |
Within-test control flow
| What | How | Details |
| Skip rest if module is missing | docutils = pytest.importorskip("docutils") | |
Fixtures
Pytest caches fixtures within the defined scope (for the given parameters).
| What | How | Details |
| Define fixture | @pytest.fixture
def first_entry():
return "a" | |
| Define fixture with module scope | @pytest.fixture(scope="module") | |
| Define fixture with cleanup | Define clean-up after yield | |
| Define fixture for use in every test | @pytest.fixture(autouse=True) | |
| Define parameterized fixture, resulting in multiple tests | @pytest.fixture(params=[1, 2, 3, 4, 5])
def number(request):
return request.param | |
| Disable GC for every test, collect in-between | @pytest.fixture(autouse=True)
def cleanup():
gc.collect()
gc.disable() | |
| Parameterize tests with a dynamic list of file paths (using fixture) | @fixture(params = glob.glob(r'data\*.csv')
def file_paths(request)
return request.param | |
| Parameterize tests with a dynamic list of file names (using fixture) | @fixture(params = fnmatch.filter(os.listdir('data'), '*.csv')
def file_names(request)
return request.param | |
| Parameterized test using a parameterizable fixture | @pytest.fixture
def tester(request):
return MyTester(request.param)
@pytest.mark.parametrize('tester', [['var1', 'var2']], indirect=True)
def test_tc1(self, tester):
tester.dothis() | |