.. _`noseintegration`:

Running tests written for nose
=======================================

``pytest`` has basic support for running tests written for nose_.

.. _nosestyle:

Usage
-------------

After :ref:`installation` type:

.. code-block:: bash

    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
----------------------

* setup and teardown at module/class/method level
* SkipTest exceptions and markers
* setup/teardown decorators
* ``__test__`` attribute on modules/classes/functions
* general usage of nose utilities

Unsupported idioms / known issues
----------------------------------

- unittest-style ``setUp, tearDown, setUpClass, tearDownClass``
  are recognized only on ``unittest.TestCase`` classes but not
  on plain classes.  ``nose`` supports 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_method``
  it 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 this issue
  <https://github.com/pytest-dev/pytest/issues/377/>`_.

- nose imports test modules with the same import path (e.g.
  ``tests.test_mode``) but different file system paths
  (e.g. ``tests/test_mode.py`` and ``other/tests/test_mode.py``)
  by extending sys.path/import semantics.   pytest does not do that
  but there is discussion in `#268 <https://github.com/pytest-dev/pytest/issues/268>`_ for adding some support.  Note that
  `nose2 choose to avoid this sys.path/import hackery <https://nose2.readthedocs.io/en/latest/differences.html#test-discovery-and-loading>`_.

  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.path`` instead of
  running against your installed code.

  You may find yourself wanting to do this if you ran ``python setup.py install``
  to set up your project, as opposed to ``python setup.py develop`` or 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.

.. _nose: https://nose.readthedocs.io/en/latest/
