How to run tests written for nose¶
pytest has basic support for running tests written for nose.
After Install pytest type:
python setup.py develop # make sure tests can import our package pytest # instead of 'nosetests'
and you should be able to run your nose style tests and make use of pytest’s capabilities.
Supported nose Idioms¶
teardown()at module/class/method level: any function or method called
setupwill be called during the setup phase for each test, same for
SkipTestexceptions and markers
__test__attribute on modules/classes/functions
general usage of nose utilities
Unsupported idioms / known issues¶
setUp, tearDown, setUpClass, tearDownClassare recognized only on
unittest.TestCaseclasses but not on plain classes.
nosesupports these methods also on plain classes but pytest deliberately does not. As nose and pytest already both support
setup_class, teardown_class, setup_method, teardown_methodit doesn’t seem useful to duplicate the unittest-API like nose does. If you however rather think pytest should support the unittest-spelling on plain classes please post to issue #377.
nose imports test modules with the same import path (e.g.
tests.test_mode) but different file system paths (e.g.
other/tests/test_mode.py) by extending sys.path/import semantics. pytest does not do that but there is discussion in issue #268 for adding some support. Note that nose2 choose to avoid this sys.path/import hackery.
If you place a conftest.py file in the root directory of your project (as determined by pytest) pytest will run tests “nose style” against the code below that directory by adding it to your
sys.pathinstead of running against your installed code.
You may find yourself wanting to do this if you ran
python setup.py installto set up your project, as opposed to
python setup.py developor any of the package manager equivalents. Installing with develop in a virtual environment like tox is recommended over this pattern.
nose-style doctests are not collected and executed correctly, also doctest fixtures don’t work.
no nose-configuration is recognized.
yield-based methods are unsupported as of pytest 4.1.0. They are fundamentally incompatible with pytest because they don’t support fixtures properly since collection and test execution are separated.
Migrating from nose to pytest¶
nose2pytest is a Python script and pytest plugin to help convert Nose-based tests into pytest-based tests. Specifically, the script transforms nose.tools.assert_* function calls into raw assert statements, while preserving format of original arguments as much as possible.