src/third_party/web_platform_tests/tools/pytest/doc/en/example/simple.rst - cobalt - Git at Google


 .. highlightlang:: python

 Basic patterns and examples
 ==========================================================

 Pass different values to a test function, depending on command line options
 ----------------------------------------------------------------------------

 .. regendoc:wipe

 Suppose we want to write a test that depends on a command line option.
 Here is a basic pattern to achieve this::

     # content of test_sample.py
     def test_answer(cmdopt):
         if cmdopt == "type1":
             print ("first")
         elif cmdopt == "type2":
             print ("second")
         assert 0 # to see what was printed


 For this to work we need to add a command line option and
 provide the ``cmdopt`` through a :ref:`fixture function <fixture function>`::

     # content of conftest.py
     import pytest

     def pytest_addoption(parser):
         parser.addoption("--cmdopt", action="store", default="type1",
             help="my option: type1 or type2")

     @pytest.fixture
     def cmdopt(request):
         return request.config.getoption("--cmdopt")

 Let's run this without supplying our new option::

     $ py.test -q test_sample.py
     F
     ======= FAILURES ========
     _______ test_answer ________

     cmdopt = 'type1'

         def test_answer(cmdopt):
             if cmdopt == "type1":
                 print ("first")
             elif cmdopt == "type2":
                 print ("second")
     >       assert 0 # to see what was printed
     E       assert 0

     test_sample.py:6: AssertionError
     --------------------------- Captured stdout call ---------------------------
     first
     1 failed in 0.12 seconds

 And now with supplying a command line option::

     $ py.test -q --cmdopt=type2
     F
     ======= FAILURES ========
     _______ test_answer ________

     cmdopt = 'type2'

         def test_answer(cmdopt):
             if cmdopt == "type1":
                 print ("first")
             elif cmdopt == "type2":
                 print ("second")
     >       assert 0 # to see what was printed
     E       assert 0

     test_sample.py:6: AssertionError
     --------------------------- Captured stdout call ---------------------------
     second
     1 failed in 0.12 seconds

 You can see that the command line option arrived in our test.  This
 completes the basic pattern.  However, one often rather wants to process
 command line options outside of the test and rather pass in different or
 more complex objects.

 Dynamically adding command line options
 --------------------------------------------------------------

 .. regendoc:wipe

 Through :confval:`addopts` you can statically add command line
 options for your project.  You can also dynamically modify
 the command line arguments before they get processed::

     # content of conftest.py
     import sys
     def pytest_cmdline_preparse(args):
         if 'xdist' in sys.modules: # pytest-xdist plugin
             import multiprocessing
             num = max(multiprocessing.cpu_count() / 2, 1)
             args[:] = ["-n", str(num)] + args

 If you have the :ref:`xdist plugin <xdist>` installed
 you will now always perform test runs using a number
 of subprocesses close to your CPU. Running in an empty
 directory with the above conftest.py::

     $ py.test
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 0 items

     ======= no tests ran in 0.12 seconds ========

 .. _`excontrolskip`:

 Control skipping of tests according to command line option
 --------------------------------------------------------------

 .. regendoc:wipe

 Here is a ``conftest.py`` file adding a ``--runslow`` command
 line option to control skipping of ``slow`` marked tests::

     # content of conftest.py

     import pytest
     def pytest_addoption(parser):
         parser.addoption("--runslow", action="store_true",
             help="run slow tests")

 We can now write a test module like this::

     # content of test_module.py

     import pytest


     slow = pytest.mark.skipif(
         not pytest.config.getoption("--runslow"),
         reason="need --runslow option to run"
     )


     def test_func_fast():
         pass


     @slow
     def test_func_slow():
         pass

 and when running it will see a skipped "slow" test::

     $ py.test -rs    # "-rs" means report details on the little 's'
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 2 items

     test_module.py .s
     ======= short test summary info ========
     SKIP [1] test_module.py:14: need --runslow option to run

     ======= 1 passed, 1 skipped in 0.12 seconds ========

 Or run it including the ``slow`` marked test::

     $ py.test --runslow
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 2 items

     test_module.py ..

     ======= 2 passed in 0.12 seconds ========

 Writing well integrated assertion helpers
 --------------------------------------------------

 .. regendoc:wipe

 If you have a test helper function called from a test you can
 use the ``pytest.fail`` marker to fail a test with a certain message.
 The test support function will not show up in the traceback if you
 set the ``__tracebackhide__`` option somewhere in the helper function.
 Example::

     # content of test_checkconfig.py
     import pytest
     def checkconfig(x):
         __tracebackhide__ = True
         if not hasattr(x, "config"):
             pytest.fail("not configured: %s" %(x,))

     def test_something():
         checkconfig(42)

 The ``__tracebackhide__`` setting influences ``pytest`` showing
 of tracebacks: the ``checkconfig`` function will not be shown
 unless the ``--fulltrace`` command line option is specified.
 Let's run our little function::

     $ py.test -q test_checkconfig.py
     F
     ======= FAILURES ========
     _______ test_something ________

         def test_something():
     >       checkconfig(42)
     E       Failed: not configured: 42

     test_checkconfig.py:8: Failed
     1 failed in 0.12 seconds

 Detect if running from within a pytest run
 --------------------------------------------------------------

 .. regendoc:wipe

 Usually it is a bad idea to make application code
 behave differently if called from a test.  But if you
 absolutely must find out if your application code is
 running from a test you can do something like this::

     # content of conftest.py

     def pytest_configure(config):
         import sys
         sys._called_from_test = True

     def pytest_unconfigure(config):
         del sys._called_from_test

 and then check for the ``sys._called_from_test`` flag::

     if hasattr(sys, '_called_from_test'):
         # called from within a test run
     else:
         # called "normally"

 accordingly in your application.  It's also a good idea
 to use your own application module rather than ``sys``
 for handling flag.

 Adding info to test report header
 --------------------------------------------------------------

 .. regendoc:wipe

 It's easy to present extra information in a ``pytest`` run::

     # content of conftest.py

     def pytest_report_header(config):
         return "project deps: mylib-1.1"

 which will add the string to the test header accordingly::

     $ py.test
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     project deps: mylib-1.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 0 items

     ======= no tests ran in 0.12 seconds ========

 .. regendoc:wipe

 You can also return a list of strings which will be considered as several
 lines of information.  You can of course also make the amount of reporting
 information on e.g. the value of ``config.option.verbose`` so that
 you present more information appropriately::

     # content of conftest.py

     def pytest_report_header(config):
         if config.option.verbose > 0:
             return ["info1: did you know that ...", "did you?"]

 which will add info only when run with "--v"::

     $ py.test -v
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1 -- $PYTHON_PREFIX/bin/python3.4
     cachedir: .cache
     info1: did you know that ...
     did you?
     rootdir: $REGENDOC_TMPDIR, inifile:
     collecting ... collected 0 items

     ======= no tests ran in 0.12 seconds ========

 and nothing when run plainly::

     $ py.test
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 0 items

     ======= no tests ran in 0.12 seconds ========

 profiling test duration
 --------------------------

 .. regendoc:wipe

 .. versionadded: 2.2

 If you have a slow running large test suite you might want to find
 out which tests are the slowest. Let's make an artificial test suite::

     # content of test_some_are_slow.py

     import time

     def test_funcfast():
         pass

     def test_funcslow1():
         time.sleep(0.1)

     def test_funcslow2():
         time.sleep(0.2)

 Now we can profile which test functions execute the slowest::

     $ py.test --durations=3
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 3 items

     test_some_are_slow.py ...

     ======= slowest 3 test durations ========
     0.20s call     test_some_are_slow.py::test_funcslow2
     0.10s call     test_some_are_slow.py::test_funcslow1
     0.00s setup    test_some_are_slow.py::test_funcfast
     ======= 3 passed in 0.12 seconds ========

 incremental testing - test steps
 ---------------------------------------------------

 .. regendoc:wipe

 Sometimes you may have a testing situation which consists of a series
 of test steps.  If one step fails it makes no sense to execute further
 steps as they are all expected to fail anyway and their tracebacks
 add no insight.  Here is a simple ``conftest.py`` file which introduces
 an ``incremental`` marker which is to be used on classes::

     # content of conftest.py

     import pytest

     def pytest_runtest_makereport(item, call):
         if "incremental" in item.keywords:
             if call.excinfo is not None:
                 parent = item.parent
                 parent._previousfailed = item

     def pytest_runtest_setup(item):
         if "incremental" in item.keywords:
             previousfailed = getattr(item.parent, "_previousfailed", None)
             if previousfailed is not None:
                 pytest.xfail("previous test failed (%s)" %previousfailed.name)

 These two hook implementations work together to abort incremental-marked
 tests in a class.  Here is a test module example::

     # content of test_step.py

     import pytest

     @pytest.mark.incremental
     class TestUserHandling:
         def test_login(self):
             pass
         def test_modification(self):
             assert 0
         def test_deletion(self):
             pass

     def test_normal():
         pass

 If we run this::

     $ py.test -rx
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 4 items

     test_step.py .Fx.
     ======= short test summary info ========
     XFAIL test_step.py::TestUserHandling::()::test_deletion
       reason: previous test failed (test_modification)

     ======= FAILURES ========
     _______ TestUserHandling.test_modification ________

     self = <test_step.TestUserHandling object at 0xdeadbeef>

         def test_modification(self):
     >       assert 0
     E       assert 0

     test_step.py:9: AssertionError
     ======= 1 failed, 2 passed, 1 xfailed in 0.12 seconds ========

 We'll see that ``test_deletion`` was not executed because ``test_modification``
 failed.  It is reported as an "expected failure".


 Package/Directory-level fixtures (setups)
 -------------------------------------------------------

 If you have nested test directories, you can have per-directory fixture scopes
 by placing fixture functions in a ``conftest.py`` file in that directory
 You can use all types of fixtures including :ref:`autouse fixtures
 <autouse fixtures>` which are the equivalent of xUnit's setup/teardown
 concept.  It's however recommended to have explicit fixture references in your
 tests or test classes rather than relying on implicitly executing
 setup/teardown functions, especially if they are far away from the actual tests.

 Here is a an example for making a ``db`` fixture available in a directory::

     # content of a/conftest.py
     import pytest

     class DB:
         pass

     @pytest.fixture(scope="session")
     def db():
         return DB()

 and then a test module in that directory::

     # content of a/test_db.py
     def test_a1(db):
         assert 0, db  # to show value

 another test module::

     # content of a/test_db2.py
     def test_a2(db):
         assert 0, db  # to show value

 and then a module in a sister directory which will not see
 the ``db`` fixture::

     # content of b/test_error.py
     def test_root(db):  # no db here, will error out
         pass

 We can run this::

     $ py.test
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 7 items

     test_step.py .Fx.
     a/test_db.py F
     a/test_db2.py F
     b/test_error.py E

     ======= ERRORS ========
     _______ ERROR at setup of test_root ________
     file $REGENDOC_TMPDIR/b/test_error.py, line 1
       def test_root(db):  # no db here, will error out
             fixture 'db' not found
             available fixtures: record_xml_property, recwarn, cache, capsys, pytestconfig, tmpdir_factory, capfd, monkeypatch, tmpdir
             use 'py.test --fixtures [testpath]' for help on them.

     $REGENDOC_TMPDIR/b/test_error.py:1
     ======= FAILURES ========
     _______ TestUserHandling.test_modification ________

     self = <test_step.TestUserHandling object at 0xdeadbeef>

         def test_modification(self):
     >       assert 0
     E       assert 0

     test_step.py:9: AssertionError
     _______ test_a1 ________

     db = <conftest.DB object at 0xdeadbeef>

         def test_a1(db):
     >       assert 0, db  # to show value
     E       AssertionError: <conftest.DB object at 0xdeadbeef>
     E       assert 0

     a/test_db.py:2: AssertionError
     _______ test_a2 ________

     db = <conftest.DB object at 0xdeadbeef>

         def test_a2(db):
     >       assert 0, db  # to show value
     E       AssertionError: <conftest.DB object at 0xdeadbeef>
     E       assert 0

     a/test_db2.py:2: AssertionError
     ======= 3 failed, 2 passed, 1 xfailed, 1 error in 0.12 seconds ========

 The two test modules in the ``a`` directory see the same ``db`` fixture instance
 while the one test in the sister-directory ``b`` doesn't see it.  We could of course
 also define a ``db`` fixture in that sister directory's ``conftest.py`` file.
 Note that each fixture is only instantiated if there is a test actually needing
 it (unless you use "autouse" fixture which are always executed ahead of the first test
 executing).


 post-process test reports / failures
 ---------------------------------------

 If you want to postprocess test reports and need access to the executing
 environment you can implement a hook that gets called when the test
 "report" object is about to be created.  Here we write out all failing
 test calls and also access a fixture (if it was used by the test) in
 case you want to query/look at it during your post processing.  In our
 case we just write some informations out to a ``failures`` file::

     # content of conftest.py

     import pytest
     import os.path

     @pytest.hookimpl(tryfirst=True, hookwrapper=True)
     def pytest_runtest_makereport(item, call):
         # execute all other hooks to obtain the report object
         outcome = yield
         rep = outcome.get_result()

         # we only look at actual failing test calls, not setup/teardown
         if rep.when == "call" and rep.failed:
             mode = "a" if os.path.exists("failures") else "w"
             with open("failures", mode) as f:
                 # let's also access a fixture for the fun of it
                 if "tmpdir" in item.fixturenames:
                     extra = " (%s)" % item.funcargs["tmpdir"]
                 else:
                     extra = ""

                 f.write(rep.nodeid + extra + "\n")


 if you then have failing tests::

     # content of test_module.py
     def test_fail1(tmpdir):
         assert 0
     def test_fail2():
         assert 0

 and run them::

     $ py.test test_module.py
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 2 items

     test_module.py FF

     ======= FAILURES ========
     _______ test_fail1 ________

     tmpdir = local('PYTEST_TMPDIR/test_fail10')

         def test_fail1(tmpdir):
     >       assert 0
     E       assert 0

     test_module.py:2: AssertionError
     _______ test_fail2 ________

         def test_fail2():
     >       assert 0
     E       assert 0

     test_module.py:4: AssertionError
     ======= 2 failed in 0.12 seconds ========

 you will have a "failures" file which contains the failing test ids::

     $ cat failures
     test_module.py::test_fail1 (PYTEST_TMPDIR/test_fail10)
     test_module.py::test_fail2

 Making test result information available in fixtures
 -----------------------------------------------------------

 .. regendoc:wipe

 If you want to make test result reports available in fixture finalizers
 here is a little example implemented via a local plugin::

     # content of conftest.py

     import pytest

     @pytest.hookimpl(tryfirst=True, hookwrapper=True)
     def pytest_runtest_makereport(item, call):
         # execute all other hooks to obtain the report object
         outcome = yield
         rep = outcome.get_result()

         # set an report attribute for each phase of a call, which can
         # be "setup", "call", "teardown"

         setattr(item, "rep_" + rep.when, rep)


     @pytest.fixture
     def something(request):
         def fin():
             # request.node is an "item" because we use the default
             # "function" scope
             if request.node.rep_setup.failed:
                 print ("setting up a test failed!", request.node.nodeid)
             elif request.node.rep_setup.passed:
                 if request.node.rep_call.failed:
                     print ("executing test failed", request.node.nodeid)
         request.addfinalizer(fin)


 if you then have failing tests::

     # content of test_module.py

     import pytest

     @pytest.fixture
     def other():
         assert 0

     def test_setup_fails(something, other):
         pass

     def test_call_fails(something):
         assert 0

     def test_fail2():
         assert 0

 and run it::

     $ py.test -s test_module.py
     ======= test session starts ========
     platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
     rootdir: $REGENDOC_TMPDIR, inifile:
     collected 3 items

     test_module.py Esetting up a test failed! test_module.py::test_setup_fails
     Fexecuting test failed test_module.py::test_call_fails
     F

     ======= ERRORS ========
     _______ ERROR at setup of test_setup_fails ________

         @pytest.fixture
         def other():
     >       assert 0
     E       assert 0

     test_module.py:6: AssertionError
     ======= FAILURES ========
     _______ test_call_fails ________

     something = None

         def test_call_fails(something):
     >       assert 0
     E       assert 0

     test_module.py:12: AssertionError
     _______ test_fail2 ________

         def test_fail2():
     >       assert 0
     E       assert 0

     test_module.py:15: AssertionError
     ======= 2 failed, 1 error in 0.12 seconds ========

 You'll see that the fixture finalizers could use the precise reporting
 information.

 Integrating pytest runner and cx_freeze
 -----------------------------------------------------------

 If you freeze your application using a tool like
 `cx_freeze <http://cx-freeze.readthedocs.org>`_ in order to distribute it
 to your end-users, it is a good idea to also package your test runner and run
 your tests using the frozen application.

 This way packaging errors such as dependencies not being
 included into the executable can be detected early while also allowing you to
 send test files to users so they can run them in their machines, which can be
 invaluable to obtain more information about a hard to reproduce bug.

 Unfortunately ``cx_freeze`` can't discover them
 automatically because of ``pytest``'s use of dynamic module loading, so you
 must declare them explicitly by using ``pytest.freeze_includes()``::

     # contents of setup.py
     from cx_Freeze import setup, Executable
     import pytest

     setup(
         name="app_main",
         executables=[Executable("app_main.py")],
         options={"build_exe":
             {
             'includes': pytest.freeze_includes()}
             },
         # ... other options
     )

 If you don't want to ship a different executable just in order to run your tests,
 you can make your program check for a certain flag and pass control
 over to ``pytest`` instead. For example::

     # contents of app_main.py
     import sys

     if len(sys.argv) > 1 and sys.argv[1] == '--pytest':
         import pytest
         sys.exit(pytest.main(sys.argv[2:]))
     else:
         # normal application execution: at this point argv can be parsed
         # by your argument-parsing library of choice as usual
         ...

 This makes it convenient to execute your tests from within your frozen
 application, using standard ``py.test`` command-line options::

     ./app_main --pytest --verbose --tb=long --junitxml=results.xml test-suite/

	.. highlightlang:: python

	Basic patterns and examples
	==========================================================

	Pass different values to a test function, depending on command line options
	----------------------------------------------------------------------------

	.. regendoc:wipe

	Suppose we want to write a test that depends on a command line option.
	Here is a basic pattern to achieve this::

	# content of test_sample.py
	def test_answer(cmdopt):
	if cmdopt == "type1":
	print ("first")
	elif cmdopt == "type2":
	print ("second")
	assert 0 # to see what was printed


	For this to work we need to add a command line option and
	provide the ``cmdopt`` through a :ref:`fixture function <fixture function>`::

	# content of conftest.py
	import pytest

	def pytest_addoption(parser):
	parser.addoption("--cmdopt", action="store", default="type1",
	help="my option: type1 or type2")

	@pytest.fixture
	def cmdopt(request):
	return request.config.getoption("--cmdopt")

	Let's run this without supplying our new option::

	$ py.test -q test_sample.py
	F
	======= FAILURES ========
	_______ test_answer ________

	cmdopt = 'type1'

	def test_answer(cmdopt):
	if cmdopt == "type1":
	print ("first")
	elif cmdopt == "type2":
	print ("second")
	> assert 0 # to see what was printed
	E assert 0

	test_sample.py:6: AssertionError
	--------------------------- Captured stdout call ---------------------------
	first
	1 failed in 0.12 seconds

	And now with supplying a command line option::

	$ py.test -q --cmdopt=type2
	F
	======= FAILURES ========
	_______ test_answer ________

	cmdopt = 'type2'

	def test_answer(cmdopt):
	if cmdopt == "type1":
	print ("first")
	elif cmdopt == "type2":
	print ("second")
	> assert 0 # to see what was printed
	E assert 0

	test_sample.py:6: AssertionError
	--------------------------- Captured stdout call ---------------------------
	second
	1 failed in 0.12 seconds

	You can see that the command line option arrived in our test. This
	completes the basic pattern. However, one often rather wants to process
	command line options outside of the test and rather pass in different or
	more complex objects.

	Dynamically adding command line options
	--------------------------------------------------------------

	.. regendoc:wipe

	Through :confval:`addopts` you can statically add command line
	options for your project. You can also dynamically modify
	the command line arguments before they get processed::

	# content of conftest.py
	import sys
	def pytest_cmdline_preparse(args):
	if 'xdist' in sys.modules: # pytest-xdist plugin
	import multiprocessing
	num = max(multiprocessing.cpu_count() / 2, 1)
	args[:] = ["-n", str(num)] + args

	If you have the :ref:`xdist plugin <xdist>` installed
	you will now always perform test runs using a number
	of subprocesses close to your CPU. Running in an empty
	directory with the above conftest.py::

	$ py.test
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 0 items

	======= no tests ran in 0.12 seconds ========

	.. _`excontrolskip`:

	Control skipping of tests according to command line option
	--------------------------------------------------------------

	.. regendoc:wipe

	Here is a ``conftest.py`` file adding a ``--runslow`` command
	line option to control skipping of ``slow`` marked tests::

	# content of conftest.py

	import pytest
	def pytest_addoption(parser):
	parser.addoption("--runslow", action="store_true",
	help="run slow tests")

	We can now write a test module like this::

	# content of test_module.py

	import pytest


	slow = pytest.mark.skipif(
	not pytest.config.getoption("--runslow"),
	reason="need --runslow option to run"
	)


	def test_func_fast():
	pass


	@slow
	def test_func_slow():
	pass

	and when running it will see a skipped "slow" test::

	$ py.test -rs # "-rs" means report details on the little 's'
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 2 items

	test_module.py .s
	======= short test summary info ========
	SKIP [1] test_module.py:14: need --runslow option to run

	======= 1 passed, 1 skipped in 0.12 seconds ========

	Or run it including the ``slow`` marked test::

	$ py.test --runslow
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 2 items

	test_module.py ..

	======= 2 passed in 0.12 seconds ========

	Writing well integrated assertion helpers
	--------------------------------------------------

	.. regendoc:wipe

	If you have a test helper function called from a test you can
	use the ``pytest.fail`` marker to fail a test with a certain message.
	The test support function will not show up in the traceback if you
	set the ``__tracebackhide__`` option somewhere in the helper function.
	Example::

	# content of test_checkconfig.py
	import pytest
	def checkconfig(x):
	__tracebackhide__ = True
	if not hasattr(x, "config"):
	pytest.fail("not configured: %s" %(x,))

	def test_something():
	checkconfig(42)

	The ``__tracebackhide__`` setting influences ``pytest`` showing
	of tracebacks: the ``checkconfig`` function will not be shown
	unless the ``--fulltrace`` command line option is specified.
	Let's run our little function::

	$ py.test -q test_checkconfig.py
	F
	======= FAILURES ========
	_______ test_something ________

	def test_something():
	> checkconfig(42)
	E Failed: not configured: 42

	test_checkconfig.py:8: Failed
	1 failed in 0.12 seconds

	Detect if running from within a pytest run
	--------------------------------------------------------------

	.. regendoc:wipe

	Usually it is a bad idea to make application code
	behave differently if called from a test. But if you
	absolutely must find out if your application code is
	running from a test you can do something like this::

	# content of conftest.py

	def pytest_configure(config):
	import sys
	sys._called_from_test = True

	def pytest_unconfigure(config):
	del sys._called_from_test

	and then check for the ``sys._called_from_test`` flag::

	if hasattr(sys, '_called_from_test'):
	# called from within a test run
	else:
	# called "normally"

	accordingly in your application. It's also a good idea
	to use your own application module rather than ``sys``
	for handling flag.

	Adding info to test report header
	--------------------------------------------------------------

	.. regendoc:wipe

	It's easy to present extra information in a ``pytest`` run::

	# content of conftest.py

	def pytest_report_header(config):
	return "project deps: mylib-1.1"

	which will add the string to the test header accordingly::

	$ py.test
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	project deps: mylib-1.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 0 items

	======= no tests ran in 0.12 seconds ========

	.. regendoc:wipe

	You can also return a list of strings which will be considered as several
	lines of information. You can of course also make the amount of reporting
	information on e.g. the value of ``config.option.verbose`` so that
	you present more information appropriately::

	# content of conftest.py

	def pytest_report_header(config):
	if config.option.verbose > 0:
	return ["info1: did you know that ...", "did you?"]

	which will add info only when run with "--v"::

	$ py.test -v
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1 -- $PYTHON_PREFIX/bin/python3.4
	cachedir: .cache
	info1: did you know that ...
	did you?
	rootdir: $REGENDOC_TMPDIR, inifile:
	collecting ... collected 0 items

	======= no tests ran in 0.12 seconds ========

	and nothing when run plainly::

	$ py.test
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 0 items

	======= no tests ran in 0.12 seconds ========

	profiling test duration
	--------------------------

	.. regendoc:wipe

	.. versionadded: 2.2

	If you have a slow running large test suite you might want to find
	out which tests are the slowest. Let's make an artificial test suite::

	# content of test_some_are_slow.py

	import time

	def test_funcfast():
	pass

	def test_funcslow1():
	time.sleep(0.1)

	def test_funcslow2():
	time.sleep(0.2)

	Now we can profile which test functions execute the slowest::

	$ py.test --durations=3
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 3 items

	test_some_are_slow.py ...

	======= slowest 3 test durations ========
	0.20s call test_some_are_slow.py::test_funcslow2
	0.10s call test_some_are_slow.py::test_funcslow1
	0.00s setup test_some_are_slow.py::test_funcfast
	======= 3 passed in 0.12 seconds ========

	incremental testing - test steps
	---------------------------------------------------

	.. regendoc:wipe

	Sometimes you may have a testing situation which consists of a series
	of test steps. If one step fails it makes no sense to execute further
	steps as they are all expected to fail anyway and their tracebacks
	add no insight. Here is a simple ``conftest.py`` file which introduces
	an ``incremental`` marker which is to be used on classes::

	# content of conftest.py

	import pytest

	def pytest_runtest_makereport(item, call):
	if "incremental" in item.keywords:
	if call.excinfo is not None:
	parent = item.parent
	parent._previousfailed = item

	def pytest_runtest_setup(item):
	if "incremental" in item.keywords:
	previousfailed = getattr(item.parent, "_previousfailed", None)
	if previousfailed is not None:
	pytest.xfail("previous test failed (%s)" %previousfailed.name)

	These two hook implementations work together to abort incremental-marked
	tests in a class. Here is a test module example::

	# content of test_step.py

	import pytest

	@pytest.mark.incremental
	class TestUserHandling:
	def test_login(self):
	pass
	def test_modification(self):
	assert 0
	def test_deletion(self):
	pass

	def test_normal():
	pass

	If we run this::

	$ py.test -rx
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 4 items

	test_step.py .Fx.
	======= short test summary info ========
	XFAIL test_step.py::TestUserHandling::()::test_deletion
	reason: previous test failed (test_modification)

	======= FAILURES ========
	_______ TestUserHandling.test_modification ________

	self = <test_step.TestUserHandling object at 0xdeadbeef>

	def test_modification(self):
	> assert 0
	E assert 0

	test_step.py:9: AssertionError
	======= 1 failed, 2 passed, 1 xfailed in 0.12 seconds ========

	We'll see that ``test_deletion`` was not executed because ``test_modification``
	failed. It is reported as an "expected failure".


	Package/Directory-level fixtures (setups)
	-------------------------------------------------------

	If you have nested test directories, you can have per-directory fixture scopes
	by placing fixture functions in a ``conftest.py`` file in that directory
	You can use all types of fixtures including :ref:`autouse fixtures
	<autouse fixtures>` which are the equivalent of xUnit's setup/teardown
	concept. It's however recommended to have explicit fixture references in your
	tests or test classes rather than relying on implicitly executing
	setup/teardown functions, especially if they are far away from the actual tests.

	Here is a an example for making a ``db`` fixture available in a directory::

	# content of a/conftest.py
	import pytest

	class DB:
	pass

	@pytest.fixture(scope="session")
	def db():
	return DB()

	and then a test module in that directory::

	# content of a/test_db.py
	def test_a1(db):
	assert 0, db # to show value

	another test module::

	# content of a/test_db2.py
	def test_a2(db):
	assert 0, db # to show value

	and then a module in a sister directory which will not see
	the ``db`` fixture::

	# content of b/test_error.py
	def test_root(db): # no db here, will error out
	pass

	We can run this::

	$ py.test
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 7 items

	test_step.py .Fx.
	a/test_db.py F
	a/test_db2.py F
	b/test_error.py E

	======= ERRORS ========
	_______ ERROR at setup of test_root ________
	file $REGENDOC_TMPDIR/b/test_error.py, line 1
	def test_root(db): # no db here, will error out
	fixture 'db' not found
	available fixtures: record_xml_property, recwarn, cache, capsys, pytestconfig, tmpdir_factory, capfd, monkeypatch, tmpdir
	use 'py.test --fixtures [testpath]' for help on them.

	$REGENDOC_TMPDIR/b/test_error.py:1
	======= FAILURES ========
	_______ TestUserHandling.test_modification ________

	self = <test_step.TestUserHandling object at 0xdeadbeef>

	def test_modification(self):
	> assert 0
	E assert 0

	test_step.py:9: AssertionError
	_______ test_a1 ________

	db = <conftest.DB object at 0xdeadbeef>

	def test_a1(db):
	> assert 0, db # to show value
	E AssertionError: <conftest.DB object at 0xdeadbeef>
	E assert 0

	a/test_db.py:2: AssertionError
	_______ test_a2 ________

	db = <conftest.DB object at 0xdeadbeef>

	def test_a2(db):
	> assert 0, db # to show value
	E AssertionError: <conftest.DB object at 0xdeadbeef>
	E assert 0

	a/test_db2.py:2: AssertionError
	======= 3 failed, 2 passed, 1 xfailed, 1 error in 0.12 seconds ========

	The two test modules in the ``a`` directory see the same ``db`` fixture instance
	while the one test in the sister-directory ``b`` doesn't see it. We could of course
	also define a ``db`` fixture in that sister directory's ``conftest.py`` file.
	Note that each fixture is only instantiated if there is a test actually needing
	it (unless you use "autouse" fixture which are always executed ahead of the first test
	executing).


	post-process test reports / failures
	---------------------------------------

	If you want to postprocess test reports and need access to the executing
	environment you can implement a hook that gets called when the test
	"report" object is about to be created. Here we write out all failing
	test calls and also access a fixture (if it was used by the test) in
	case you want to query/look at it during your post processing. In our
	case we just write some informations out to a ``failures`` file::

	# content of conftest.py

	import pytest
	import os.path

	@pytest.hookimpl(tryfirst=True, hookwrapper=True)
	def pytest_runtest_makereport(item, call):
	# execute all other hooks to obtain the report object
	outcome = yield
	rep = outcome.get_result()

	# we only look at actual failing test calls, not setup/teardown
	if rep.when == "call" and rep.failed:
	mode = "a" if os.path.exists("failures") else "w"
	with open("failures", mode) as f:
	# let's also access a fixture for the fun of it
	if "tmpdir" in item.fixturenames:
	extra = " (%s)" % item.funcargs["tmpdir"]
	else:
	extra = ""

	f.write(rep.nodeid + extra + "\n")


	if you then have failing tests::

	# content of test_module.py
	def test_fail1(tmpdir):
	assert 0
	def test_fail2():
	assert 0

	and run them::

	$ py.test test_module.py
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 2 items

	test_module.py FF

	======= FAILURES ========
	_______ test_fail1 ________

	tmpdir = local('PYTEST_TMPDIR/test_fail10')

	def test_fail1(tmpdir):
	> assert 0
	E assert 0

	test_module.py:2: AssertionError
	_______ test_fail2 ________

	def test_fail2():
	> assert 0
	E assert 0

	test_module.py:4: AssertionError
	======= 2 failed in 0.12 seconds ========

	you will have a "failures" file which contains the failing test ids::

	$ cat failures
	test_module.py::test_fail1 (PYTEST_TMPDIR/test_fail10)
	test_module.py::test_fail2

	Making test result information available in fixtures
	-----------------------------------------------------------

	.. regendoc:wipe

	If you want to make test result reports available in fixture finalizers
	here is a little example implemented via a local plugin::

	# content of conftest.py

	import pytest

	@pytest.hookimpl(tryfirst=True, hookwrapper=True)
	def pytest_runtest_makereport(item, call):
	# execute all other hooks to obtain the report object
	outcome = yield
	rep = outcome.get_result()

	# set an report attribute for each phase of a call, which can
	# be "setup", "call", "teardown"

	setattr(item, "rep_" + rep.when, rep)


	@pytest.fixture
	def something(request):
	def fin():
	# request.node is an "item" because we use the default
	# "function" scope
	if request.node.rep_setup.failed:
	print ("setting up a test failed!", request.node.nodeid)
	elif request.node.rep_setup.passed:
	if request.node.rep_call.failed:
	print ("executing test failed", request.node.nodeid)
	request.addfinalizer(fin)


	if you then have failing tests::

	# content of test_module.py

	import pytest

	@pytest.fixture
	def other():
	assert 0

	def test_setup_fails(something, other):
	pass

	def test_call_fails(something):
	assert 0

	def test_fail2():
	assert 0

	and run it::

	$ py.test -s test_module.py
	======= test session starts ========
	platform linux -- Python 3.4.0, pytest-2.9.1, py-1.4.31, pluggy-0.3.1
	rootdir: $REGENDOC_TMPDIR, inifile:
	collected 3 items

	test_module.py Esetting up a test failed! test_module.py::test_setup_fails
	Fexecuting test failed test_module.py::test_call_fails
	F

	======= ERRORS ========
	_______ ERROR at setup of test_setup_fails ________

	@pytest.fixture
	def other():
	> assert 0
	E assert 0

	test_module.py:6: AssertionError
	======= FAILURES ========
	_______ test_call_fails ________

	something = None

	def test_call_fails(something):
	> assert 0
	E assert 0

	test_module.py:12: AssertionError
	_______ test_fail2 ________

	def test_fail2():
	> assert 0
	E assert 0

	test_module.py:15: AssertionError
	======= 2 failed, 1 error in 0.12 seconds ========

	You'll see that the fixture finalizers could use the precise reporting
	information.

	Integrating pytest runner and cx_freeze
	-----------------------------------------------------------

	If you freeze your application using a tool like
	`cx_freeze <http://cx-freeze.readthedocs.org>`_ in order to distribute it
	to your end-users, it is a good idea to also package your test runner and run
	your tests using the frozen application.

	This way packaging errors such as dependencies not being
	included into the executable can be detected early while also allowing you to
	send test files to users so they can run them in their machines, which can be
	invaluable to obtain more information about a hard to reproduce bug.

	Unfortunately ``cx_freeze`` can't discover them
	automatically because of ``pytest``'s use of dynamic module loading, so you
	must declare them explicitly by using ``pytest.freeze_includes()``::

	# contents of setup.py
	from cx_Freeze import setup, Executable
	import pytest

	setup(
	name="app_main",
	executables=[Executable("app_main.py")],
	options={"build_exe":
	{
	'includes': pytest.freeze_includes()}
	},
	# ... other options
	)

	If you don't want to ship a different executable just in order to run your tests,
	you can make your program check for a certain flag and pass control
	over to ``pytest`` instead. For example::

	# contents of app_main.py
	import sys

	if len(sys.argv) > 1 and sys.argv[1] == '--pytest':
	import pytest
	sys.exit(pytest.main(sys.argv[2:]))
	else:
	# normal application execution: at this point argv can be parsed
	# by your argument-parsing library of choice as usual
	...

	This makes it convenient to execute your tests from within your frozen
	application, using standard ``py.test`` command-line options::

	./app_main --pytest --verbose --tb=long --junitxml=results.xml test-suite/