283 lines
9.1 KiB
Plaintext
283 lines
9.1 KiB
Plaintext
Writing, managing and understanding plugins
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=============================================
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.. _`local plugin`:
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py.test implements all aspects of configuration, collection, running and reporting by calling `well specified hooks`_. Virtually any Python module can be registered as a plugin. It can implement any number of hook functions (usually two or three) which all have a ``pytest_`` prefix, making hook functions easy to distinguish and find. There are three basic locations types::
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* builtin plugins: loaded from py.test's own `pytest/plugin`_ directory.
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* `external plugins`_: modules discovered through `setuptools entry points`_
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* `conftest.py plugins`_: modules auto-discovered in test directories
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.. _`pytest/plugin`: http://bitbucket.org/hpk42/pytest/src/tip/pytest/plugin/
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.. _`conftest.py plugins`:
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conftest.py: local per-directory plugins
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--------------------------------------------------------------
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local ``conftest.py`` plugins contain directory-specific hook
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implementations. Collection and test running activities will
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invoke all hooks defined in "higher up" ``conftest.py`` files.
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Example: Assume the following layout and content of files::
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a/conftest.py:
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def pytest_runtest_setup(item):
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# called for running each test in 'a' directory
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print ("setting up", item)
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a/test_in_subdir.py:
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def test_sub():
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pass
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test_flat.py:
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def test_flat():
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pass
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Here is how you might run it::
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py.test test_flat.py # will not show "setting up"
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py.test a/test_sub.py # will show "setting up"
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A note on ordering: ``py.test`` loads all ``conftest.py`` files upwards
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from the command line file arguments. It usually performs look up
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right-to-left, i.e. the hooks in "closer" conftest files will be called
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earlier than further away ones.
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.. Note::
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If you have ``conftest.py`` files which do not reside in a
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python package directory (i.e. one containing an ``__init__.py``) then
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"import conftest" can be ambigous because there might be other
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``conftest.py`` files as well on your PYTHONPATH or ``sys.path``.
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It is thus good practise for projects to either put ``conftest.py``
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under a package scope or to never import anything from a
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conftest.py file.
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.. _`installing plugins`:
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.. _`external plugins`:
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Installing External Plugins
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------------------------------------------------------
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Installing a plugin happens through any usual Python installation
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tool, for example::
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pip install pytest-NAME
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pip uninstall pytest-NAME
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If a plugin is installed, py.test automatically finds and integrates it,
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there is no need to activate it. If you don't need a plugin anymore simply
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de-install it. You can find a list of valid plugins through a
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`pytest- pypi.python.org search`_.
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.. _`available installable plugins`:
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.. _`pytest- pypi.python.org search`: http://pypi.python.org/pypi?%3Aaction=search&term=pytest-&submit=search
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.. _`setuptools entry points`:
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Writing an installable plugin
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------------------------------------------------------
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.. _`Distribute`: http://pypi.python.org/pypi/distribute
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.. _`setuptools`: http://pypi.python.org/pypi/setuptools
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If you want to write a plugin, there are many real-life examples
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you can copy from:
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* around 20 `builtin plugins`_ which comprise py.test's own functionality
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* around 10 `external plugins`_ providing additional features
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If you want to make your plugin externally available, you
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may define a so called entry point for your distribution so
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that ``py.test`` finds your plugin module. Entry points are
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a feature that is provided by `setuptools`_ or `Distribute`_.
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The concrete entry point is ``pytest11``. To make your plugin
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available you can insert the following lines in your
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setuptools/distribute-based setup-invocation:
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.. sourcecode:: python
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# sample ./setup.py file
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from setuptools import setup
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setup(
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name="myproject",
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packages = ['myproject']
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# the following makes a plugin available to py.test
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entry_points = {
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'pytest11': [
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'name_of_plugin = myproject.pluginmodule',
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]
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},
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)
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If a package is installed this way, py.test will load
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``myproject.pluginmodule`` and accordingly call functions
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if they match the `well specified hooks`_.
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Plugin discovery order at tool startup
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--------------------------------------------
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py.test loads plugin modules at tool startup in the following way:
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* by loading all builtin plugins
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* by loading all plugins registered through `setuptools entry points`_.
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* by pre-scanning the command line for the ``-p name`` option
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and loading the specified plugin before actual command line parsing.
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* by loading all :file:`conftest.py` files as inferred by the command line
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invocation (test files and all of its *parent* directories).
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Note that ``conftest.py`` files from *sub* directories are by default
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not loaded at tool startup.
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* by recursively loading all plugins specified by the
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``pytest_plugins`` variable in ``conftest.py`` files
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Requiring/Loading plugins in a test module or conftest file
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-------------------------------------------------------------
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You can require plugins in a test module or a conftest file like this::
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pytest_plugins = "name1", "name2",
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When the test module or conftest plugin is loaded the specified plugins
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will be loaded as well. You can also use dotted path like this::
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pytest_plugins = "myapp.testsupport.myplugin"
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which will import the specified module as a py.test plugin.
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.. _`setuptools entry points`:
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.. _registered:
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Accessing another plugin by name
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--------------------------------------------
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If a plugin wants to collaborate with code from
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another plugin it can obtain a reference through
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the plugin manager like this:
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.. sourcecode:: python
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plugin = config.pluginmanager.getplugin("name_of_plugin")
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If you want to look at the names of existing plugins, use
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the ``--traceconfig`` option.
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.. _`well specified hooks`:
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py.test hook reference
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====================================
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hook specification and validation
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-----------------------------------------
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py.test calls hook functions to implement initialization, running,
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test execution and reporting. When py.test loads a plugin it validates
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that all hook functions conform to their respective hook specification.
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Each hook function name and its argument names need to match a hook
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specification exactly but it is allowed for a hook function to accept
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*less* parameters than specified. If you mistype argument names or the
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hook name itself you get useful errors.
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initialisation, command line and configuration hooks
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--------------------------------------------------------------------
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.. currentmodule:: pytest.hookspec
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.. autofunction:: pytest_cmdline_parse
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.. autofunction:: pytest_namespace
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.. autofunction:: pytest_addoption
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.. autofunction:: pytest_cmdline_main
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.. autofunction:: pytest_configure
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.. autofunction:: pytest_unconfigure
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generic "runtest" hooks
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------------------------------
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All all runtest related hooks receive a :py:class:`pytest.collect.Item` object.
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.. autofunction:: pytest_runtest_protocol
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.. autofunction:: pytest_runtest_setup
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.. autofunction:: pytest_runtest_call
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.. autofunction:: pytest_runtest_teardown
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.. autofunction:: pytest_runtest_makereport
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For deeper understanding you may look at the default implementation of
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these hooks in :py:mod:`pytest.plugin.runner` and maybe also
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in :py:mod:`pytest.plugin.pdb` which intercepts creation
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of reports in order to drop to interactive debugging.
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The :py:mod:`pytest.plugin.terminal` reported specifically uses
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the reporting hook to print information about a test run.
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collection hooks
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------------------------------
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py.test calls the following hooks for collecting files and directories:
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.. autofunction:: pytest_ignore_collect
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.. autofunction:: pytest_collect_directory
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.. autofunction:: pytest_collect_file
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For influencing the collection of objects in Python modules
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you can use the following hook:
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.. autofunction:: pytest_pycollect_makeitem
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reporting hooks
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------------------------------
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Collection related reporting hooks:
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.. autofunction: pytest_collectstart
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.. autofunction: pytest_itemcollected
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.. autofunction: pytest_collectreport
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.. autofunction: pytest_deselected
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And here is the central hook for reporting about
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test execution:
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.. autofunction: pytest_runtest_logreport
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Reference of important objects involved in hooks
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===========================================================
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.. autoclass:: pytest.plugin.config.Config
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:members:
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.. autoclass:: pytest.plugin.config.Parser
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:members:
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.. autoclass:: pytest.plugin.session.Node(name, parent)
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:members:
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..
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.. autoclass:: pytest.plugin.session.File(fspath, parent)
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:members:
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.. autoclass:: pytest.plugin.session.Item(name, parent)
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:members:
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.. autoclass:: pytest.plugin.python.Module(name, parent)
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:members:
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.. autoclass:: pytest.plugin.python.Class(name, parent)
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:members:
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.. autoclass:: pytest.plugin.python.Function(name, parent)
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:members:
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.. autoclass:: pytest.plugin.runner.CallInfo
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:members:
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.. autoclass:: pytest.plugin.runner.TestReport
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:members:
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