.. _`mark examples`:

Working with custom markers
=================================================

Here are some example using the :ref:`mark` mechanism.

Marking test functions and selecting them for a run
----------------------------------------------------

You can "mark" a test function with custom metadata like this::

    # content of test_server.py

    import pytest
    @pytest.mark.webtest
    def test_send_http():
        pass # perform some webtest test for your app
    def test_something_quick():
        pass

.. versionadded:: 2.2

You can then restrict a test run to only run tests marked with ``webtest``::

    $ py.test -v -m webtest
    =========================== test session starts ============================
    platform darwin -- Python 2.7.1 -- pytest-2.2.2 -- /Users/hpk/venv/0/bin/python
    collecting ... collected 2 items
    
    test_server.py:3: test_send_http PASSED
    
    =================== 1 tests deselected by "-m 'webtest'" ===================
    ================== 1 passed, 1 deselected in 0.01 seconds ==================

Or the inverse, running all tests except the webtest ones::
    
    $ py.test -v -m "not webtest"
    =========================== test session starts ============================
    platform darwin -- Python 2.7.1 -- pytest-2.2.2 -- /Users/hpk/venv/0/bin/python
    collecting ... collected 2 items
    
    test_server.py:6: test_something_quick PASSED
    
    ================= 1 tests deselected by "-m 'not webtest'" =================
    ================== 1 passed, 1 deselected in 0.02 seconds ==================

Registering markers
-------------------------------------

.. versionadded:: 2.2

.. ini-syntax for custom markers:

Registering markers for your test suite is simple::

    # content of pytest.ini
    [pytest]
    markers =
        webtest: mark a test as a webtest.

You can ask which markers exist for your test suite - the list includes our just defined ``webtest`` markers::

    $ py.test --markers
    @pytest.mark.webtest: mark a test as a webtest.
    
    @pytest.mark.skipif(*conditions): skip the given test function if evaluation of all conditions has a True value.  Evaluation happens within the module global context. Example: skipif('sys.platform == "win32"') skips the test if we are on the win32 platform. 
    
    @pytest.mark.xfail(*conditions, reason=None, run=True): mark the the test function as an expected failure. Optionally specify a reason and run=False if you don't even want to execute the test function. Any positional condition strings will be evaluated (like with skipif) and if one is False the marker will not be applied.
    
    @pytest.mark.parametrize(argnames, argvalues): call a test function multiple times passing in multiple different argument value sets. Example: @parametrize('arg1', [1,2]) would lead to two calls of the decorated test function, one with arg1=1 and another with arg1=2.
    
    @pytest.mark.tryfirst: mark a hook implementation function such that the plugin machinery will try to call it first/as early as possible.
    
    @pytest.mark.trylast: mark a hook implementation function such that the plugin machinery will try to call it last/as late as possible.
    

For an example on how to add and work with markers from a plugin, see
:ref:`adding a custom marker from a plugin`.

.. note::

    It is recommended to explicitely register markers so that:

    * there is one place in your test suite defining your markers

    * asking for existing markers via ``py.test --markers`` gives good output

    * typos in function markers are treated as an error if you use
      the ``--strict`` option. Later versions of py.test are probably
      going to treat non-registered markers as an error.

.. _`scoped-marking`:

Marking whole classes or modules
----------------------------------------------------

If you are programming with Python 2.6 or later you may use ``pytest.mark``
decorators with classes to apply markers to all of its test methods::

    # content of test_mark_classlevel.py
    import pytest
    @pytest.mark.webtest
    class TestClass:
        def test_startup(self):
            pass
        def test_startup_and_more(self):
            pass

This is equivalent to directly applying the decorator to the
two test functions.

To remain backward-compatible with Python 2.4 you can also set a
``pytestmark`` attribute on a TestClass like this::

    import pytest

    class TestClass:
        pytestmark = pytest.mark.webtest

or if you need to use multiple markers you can use a list::

    import pytest

    class TestClass:
        pytestmark = [pytest.mark.webtest, pytest.mark.slowtest]

You can also set a module level marker::

    import pytest
    pytestmark = pytest.mark.webtest

in which case it will be applied to all functions and
methods defined in the module.


Using ``-k TEXT`` to select tests
----------------------------------------------------

You can use the ``-k`` command line option to only run tests with names matching
the given argument::

    $ py.test -k send_http  # running with the above defined examples
    =========================== test session starts ============================
    platform darwin -- Python 2.7.1 -- pytest-2.2.2
    collecting ... collected 4 items
    
    test_server.py .
    
    =================== 3 tests deselected by '-ksend_http' ====================
    ================== 1 passed, 3 deselected in 0.02 seconds ==================

And you can also run all tests except the ones that match the keyword::

    $ py.test -k-send_http
    =========================== test session starts ============================
    platform darwin -- Python 2.7.1 -- pytest-2.2.2
    collecting ... collected 4 items
    
    test_mark_classlevel.py ..
    test_server.py .
    
    =================== 1 tests deselected by '-k-send_http' ===================
    ================== 3 passed, 1 deselected in 0.03 seconds ==================

Or to only select the class::

    $ py.test -kTestClass
    =========================== test session starts ============================
    platform darwin -- Python 2.7.1 -- pytest-2.2.2
    collecting ... collected 4 items
    
    test_mark_classlevel.py ..
    
    =================== 2 tests deselected by '-kTestClass' ====================
    ================== 2 passed, 2 deselected in 0.03 seconds ==================

.. _`adding a custom marker from a plugin`:

Custom marker and command line option to control test runs
----------------------------------------------------------

.. regendoc:wipe

Plugins can provide custom markers and implement specific behaviour
based on it. This is a self-contained example which adds a command
line option and a parametrized test function marker to run tests
specifies via named environments::

    # content of conftest.py

    import pytest
    def pytest_addoption(parser):
        parser.addoption("-E", dest="env", action="store", metavar="NAME",
            help="only run tests matching the environment NAME.")

    def pytest_configure(config):
        # register an additional marker
        config.addinivalue_line("markers",
            "env(name): mark test to run only on named environment")

    def pytest_runtest_setup(item):
        if not isinstance(item, item.Function):
            return
        if hasattr(item.obj, 'env'):
            envmarker = getattr(item.obj, 'env')
            envname = envmarker.args[0]
            if envname != item.config.option.env:
                pytest.skip("test requires env %r" % envname)

A test file using this local plugin::

    # content of test_someenv.py

    import pytest
    @pytest.mark.env("stage1")
    def test_basic_db_operation():
        pass

and an example invocations specifying a different environment than what
the test needs::

    $ py.test -E stage2
    =========================== test session starts ============================
    platform darwin -- Python 2.7.1 -- pytest-2.2.2
    collecting ... collected 1 items
    
    test_someenv.py s
    
    ======================== 1 skipped in 0.02 seconds =========================
  
and here is one that specifies exactly the environment needed::

    $ py.test -E stage1
    =========================== test session starts ============================
    platform darwin -- Python 2.7.1 -- pytest-2.2.2
    collecting ... collected 1 items
    
    test_someenv.py .
    
    ========================= 1 passed in 0.02 seconds =========================

The ``--markers`` option always gives you a list of available markers::

    $ py.test --markers
    @pytest.mark.env(name): mark test to run only on named environment
    
    @pytest.mark.skipif(*conditions): skip the given test function if evaluation of all conditions has a True value.  Evaluation happens within the module global context. Example: skipif('sys.platform == "win32"') skips the test if we are on the win32 platform. 
    
    @pytest.mark.xfail(*conditions, reason=None, run=True): mark the the test function as an expected failure. Optionally specify a reason and run=False if you don't even want to execute the test function. Any positional condition strings will be evaluated (like with skipif) and if one is False the marker will not be applied.
    
    @pytest.mark.parametrize(argnames, argvalues): call a test function multiple times passing in multiple different argument value sets. Example: @parametrize('arg1', [1,2]) would lead to two calls of the decorated test function, one with arg1=1 and another with arg1=2.
    
    @pytest.mark.tryfirst: mark a hook implementation function such that the plugin machinery will try to call it first/as early as possible.
    
    @pytest.mark.trylast: mark a hook implementation function such that the plugin machinery will try to call it last/as late as possible.

    
Reading markers which were set from multiple places
----------------------------------------------------

.. versionadded: 2.2.2

If you are heavily using markers in your test suite you may encounter the case where a marker is applied several times to a test function.  From plugin
code you can read over all such settings.  Example::

    # content of test_mark_three_times.py
    import pytest
    pytestmark = pytest.mark.glob("module", x=1)

    @pytest.mark.glob("class", x=2)
    class TestClass:
        @pytest.mark.glob("function", x=3)
        def test_something(self):
            pass

Here we have the marker "glob" applied three times to the same
test function.  From a conftest file we can read it like this::

    # content of conftest.py

    def pytest_runtest_setup(item):
        g = getattr(item.obj, 'glob', None)
        if g is not None:
            for info in g:
                print ("glob args=%s kwargs=%s" %(info.args, info.kwargs))

Let's run this without capturing output and see what we get::

    $ py.test -q -s 
    collecting ... collected 2 items
    ..
    2 passed in 0.02 seconds
    glob args=('function',) kwargs={'x': 3}
    glob args=('class',) kwargs={'x': 2}
    glob args=('module',) kwargs={'x': 1}