test_ok2/doc/en/example/markers.txt

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.. _`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
def test_another():
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 linux2 -- Python 2.7.3 -- pytest-2.3.5 -- /home/hpk/p/pytest/.tox/regen/bin/python
collecting ... collected 3 items
test_server.py:3: test_send_http PASSED
=================== 2 tests deselected by "-m 'webtest'" ===================
================== 1 passed, 2 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 linux2 -- Python 2.7.3 -- pytest-2.3.5 -- /home/hpk/p/pytest/.tox/regen/bin/python
collecting ... collected 3 items
test_server.py:6: test_something_quick PASSED
test_server.py:8: test_another PASSED
================= 1 tests deselected by "-m 'not webtest'" =================
================== 2 passed, 1 deselected in 0.01 seconds ==================
Using ``-k expr`` to select tests based on their name
-------------------------------------------------------
.. versionadded: 2.0/2.3.4
You can use the ``-k`` command line option to specify an expression
which implements a substring match on the test names instead of the
exact match on markers that ``-m`` provides. This makes it easy to
select tests based on their names::
$ py.test -v -k http # running with the above defined example module
=========================== test session starts ============================
platform linux2 -- Python 2.7.3 -- pytest-2.3.5 -- /home/hpk/p/pytest/.tox/regen/bin/python
collecting ... collected 3 items
test_server.py:3: test_send_http PASSED
====================== 2 tests deselected by '-khttp' ======================
================== 1 passed, 2 deselected in 0.01 seconds ==================
And you can also run all tests except the ones that match the keyword::
$ py.test -k "not send_http" -v
=========================== test session starts ============================
platform linux2 -- Python 2.7.3 -- pytest-2.3.5 -- /home/hpk/p/pytest/.tox/regen/bin/python
collecting ... collected 3 items
test_server.py:6: test_something_quick PASSED
test_server.py:8: test_another PASSED
================= 1 tests deselected by '-knot send_http' ==================
================== 2 passed, 1 deselected in 0.01 seconds ==================
Or to select "http" and "quick" tests::
$ py.test -k "http or quick" -v
=========================== test session starts ============================
platform linux2 -- Python 2.7.3 -- pytest-2.3.5 -- /home/hpk/p/pytest/.tox/regen/bin/python
collecting ... collected 3 items
test_server.py:3: test_send_http PASSED
test_server.py:6: test_something_quick PASSED
================= 1 tests deselected by '-khttp or quick' ==================
================== 2 passed, 1 deselected in 0.01 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(condition): skip the given test function if eval(condition) results in 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. see http://pytest.org/latest/skipping.html
@pytest.mark.xfail(condition, reason=None, run=True): mark the the test function as an expected failure if eval(condition) has a True value. Optionally specify a reason for better reporting and run=False if you don't even want to execute the test function. See http://pytest.org/latest/skipping.html
@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. see http://pytest.org/latest/parametrize.html for more info and examples.
@pytest.mark.usefixtures(fixturename1, fixturename2, ...): mark tests as needing all of the specified fixtures. see http://pytest.org/latest/fixture.html#usefixtures
@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.
.. _`marking individual tests when using parametrize`:
Marking individual tests when using parametrize
-----------------------------------------------
When using parametrize, applying a mark will make it apply
to each individual test. However it is also possible to
apply a marker to an individual test instance::
import pytest
@pytest.mark.foo
@pytest.mark.parametrize(("n", "expected"), [
(1, 2),
pytest.mark.bar((1, 3)),
(2, 3),
])
def test_increment(n, expected):
assert n + 1 == expected
In this example the mark "foo" will apply to each of the three
tests, whereas the "bar" mark is only applied to the second test.
Skip and xfail marks can also be applied in this way, see :ref:`skip/xfail with parametrize`.
.. _`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", 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):
envmarker = item.keywords.get("env", None)
if envmarker is not None:
envname = envmarker.args[0]
if envname != item.config.getoption("-E"):
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 linux2 -- Python 2.7.3 -- pytest-2.3.5
collected 1 items
test_someenv.py s
======================== 1 skipped in 0.01 seconds =========================
and here is one that specifies exactly the environment needed::
$ py.test -E stage1
=========================== test session starts ============================
platform linux2 -- Python 2.7.3 -- pytest-2.3.5
collected 1 items
test_someenv.py .
========================= 1 passed in 0.01 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(condition): skip the given test function if eval(condition) results in 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. see http://pytest.org/latest/skipping.html
@pytest.mark.xfail(condition, reason=None, run=True): mark the the test function as an expected failure if eval(condition) has a True value. Optionally specify a reason for better reporting and run=False if you don't even want to execute the test function. See http://pytest.org/latest/skipping.html
@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. see http://pytest.org/latest/parametrize.html for more info and examples.
@pytest.mark.usefixtures(fixturename1, fixturename2, ...): mark tests as needing all of the specified fixtures. see http://pytest.org/latest/fixture.html#usefixtures
@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
.. regendoc:wipe
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
import sys
def pytest_runtest_setup(item):
g = item.keywords.get("glob", None)
if g is not None:
for info in g:
print ("glob args=%s kwargs=%s" %(info.args, info.kwargs))
sys.stdout.flush()
Let's run this without capturing output and see what we get::
$ py.test -q -s
glob args=('function',) kwargs={'x': 3}
glob args=('class',) kwargs={'x': 2}
glob args=('module',) kwargs={'x': 1}
.
marking platform specific tests with pytest
--------------------------------------------------------------
.. regendoc:wipe
Consider you have a test suite which marks tests for particular platforms,
namely ``pytest.mark.osx``, ``pytest.mark.win32`` etc. and you
also have tests that run on all platforms and have no specific
marker. If you now want to have a way to only run the tests
for your particular platform, you could use the following plugin::
# content of conftest.py
#
import sys
import pytest
ALL = set("osx linux2 win32".split())
def pytest_runtest_setup(item):
if isinstance(item, item.Function):
plat = sys.platform
if plat not in item.keywords:
if ALL.intersection(item.keywords):
pytest.skip("cannot run on platform %s" %(plat))
then tests will be skipped if they were specified for a different platform.
Let's do a little test file to show how this looks like::
# content of test_plat.py
import pytest
@pytest.mark.osx
def test_if_apple_is_evil():
pass
@pytest.mark.linux2
def test_if_linux_works():
pass
@pytest.mark.win32
def test_if_win32_crashes():
pass
def test_runs_everywhere():
pass
then you will see two test skipped and two executed tests as expected::
$ py.test -rs # this option reports skip reasons
=========================== test session starts ============================
platform linux2 -- Python 2.7.3 -- pytest-2.3.5
collected 4 items
test_plat.py s.s.
========================= short test summary info ==========================
SKIP [2] /tmp/doc-exec-273/conftest.py:12: cannot run on platform linux2
=================== 2 passed, 2 skipped in 0.01 seconds ====================
Note that if you specify a platform via the marker-command line option like this::
$ py.test -m linux2
=========================== test session starts ============================
platform linux2 -- Python 2.7.3 -- pytest-2.3.5
collected 4 items
test_plat.py .
=================== 3 tests deselected by "-m 'linux2'" ====================
================== 1 passed, 3 deselected in 0.01 seconds ==================
then the unmarked-tests will not be run. It is thus a way to restrict the run to the specific tests.
Automatically adding markers based on test names
--------------------------------------------------------
.. regendoc:wipe
If you a test suite where test function names indicate a certain
type of test, you can implement a hook that automatically defines
markers so that you can use the ``-m`` option with it. Let's look
at this test module::
# content of test_module.py
def test_interface_simple():
assert 0
def test_interface_complex():
assert 0
def test_event_simple():
assert 0
def test_something_else():
assert 0
We want to dynamically define two markers and can do it in a
``conftest.py`` plugin::
# content of conftest.py
import pytest
def pytest_collection_modifyitems(items):
for item in items:
if "interface" in item.nodeid:
item.keywords["interface"] = pytest.mark.interface
elif "event" in item.nodeid:
item.keywords["event"] = pytest.mark.event
We can now use the ``-m option`` to select one set::
$ py.test -m interface --tb=short
=========================== test session starts ============================
platform linux2 -- Python 2.7.3 -- pytest-2.3.5
collected 4 items
test_module.py FF
================================= FAILURES =================================
__________________________ test_interface_simple ___________________________
test_module.py:3: in test_interface_simple
> assert 0
E assert 0
__________________________ test_interface_complex __________________________
test_module.py:6: in test_interface_complex
> assert 0
E assert 0
================== 2 tests deselected by "-m 'interface'" ==================
================== 2 failed, 2 deselected in 0.01 seconds ==================
or to select both "event" and "interface" tests::
$ py.test -m "interface or event" --tb=short
=========================== test session starts ============================
platform linux2 -- Python 2.7.3 -- pytest-2.3.5
collected 4 items
test_module.py FFF
================================= FAILURES =================================
__________________________ test_interface_simple ___________________________
test_module.py:3: in test_interface_simple
> assert 0
E assert 0
__________________________ test_interface_complex __________________________
test_module.py:6: in test_interface_complex
> assert 0
E assert 0
____________________________ test_event_simple _____________________________
test_module.py:9: in test_event_simple
> assert 0
E assert 0
============= 1 tests deselected by "-m 'interface or event'" ==============
================== 3 failed, 1 deselected in 0.02 seconds ==================