The discover module is a backport of the automatic test discovery from python-trunk (what will become Python 2.7 & 3.2) to work with Python 2.4 or more recent (including Python 3.0).
Test discovery allows you to run all the unittest based tests (or just a subset of them) in your project without you having to write your own test collection or running machinery. Once installed, test discovery can be invoked with ``python -m discover``. I've tested the discover module with Python 2.4 and 3.0.
The discover module also implements the ``load_tests`` protocol which allows you to customize test loading from modules and packages. Test discovery and ``load_tests`` are implemented in the ``DiscoveringTestLoader`` which can be used from your own test framework.
* discover module on PyPI http://pypi.python.org/pypi/discover
discover can be installed with pip or easy_install. After installing switch the current directory to the top level directory of your project and run::
python -m discover python discover.py
This will discover all tests (with certain restrictions) from the current directory. The discover module has several options to control its behavior (full usage options are displayed with ``python -m discover -h``)::
Usage: discover.py [options]
Options: -v, --verbose Verbose output -s directory Directory to start discovery ('.' default) -p pattern Pattern to match test files ('test*.py' default) -t directory Top level directory of project (default to start directory)
For test discovery all test modules must be importable from the top level directory of the project.
For example to use a different pattern for matching test modules run::
python -m discover -p '*test.py'
(Remember to put quotes around the test pattern or shells like bash will do shell expansion rather than passing the pattern through to discover.)
Test discovery is implemented in ``discover.DiscoveringTestLoader.discover``. As well as using discover as a command line script you can import ``DiscoveringTestLoader``, which is a subclass of ``unittest.TestLoader``, and use it in your test framework.
This method finds and returns all test modules from the specified start directory, recursing into subdirectories to find them. Only test files that match *pattern* will be loaded. (Using shell style pattern matching.)
All test modules must be importable from the top level of the project. If the start directory is not the top level directory then the top level directory must be specified separately.
The ``load_tests`` protocol allows test modules and packages to customize how they are loaded. This is implemented in ``discover.DiscoveringTestLoader.loadTestsFromModule``. If a test module defines a ``load_tests`` function then tests are loaded from the module by calling ``load_tests`` with three arguments: `loader`, `standard_tests`, `None`.
If a test package name (directory with `__init__.py`) matches the pattern then the package will be checked for a ``load_tests`` function. If this exists then it will be called with *loader*, *tests*, *pattern*.
If ``load_tests`` exists then discovery does *not* recurse into the package, ``load_tests`` is responsible for loading all tests in the package.
The pattern is deliberately not stored as a loader attribute so that packages can continue discovery themselves. *top_level_dir* is stored so ``load_tests`` does not need to pass this argument in to ``loader.discover()``.
discover.py is maintained in a google code project (where bugs and feature requests should be posted): http://code.google.com/p/unittest-ext/
The latest development version of discover.py can be found at: http://code.google.com/p/unittest-ext/source/browse/trunk/discover.py