413 lines
12 KiB
ReStructuredText
413 lines
12 KiB
ReStructuredText
.. _`skip and xfail`:
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.. _skipping:
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Skip and xfail: dealing with tests that cannot succeed
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=====================================================================
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You can mark test functions that cannot be run on certain platforms
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or that you expect to fail so pytest can deal with them accordingly and
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present a summary of the test session, while keeping the test suite *green*.
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A **skip** means that you expect your test to pass only if some conditions are met,
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otherwise pytest should skip running the test altogether. Common examples are skipping
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windows-only tests on non-windows platforms, or skipping tests that depend on an external
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resource which is not available at the moment (for example a database).
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A **xfail** means that you expect a test to fail for some reason.
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A common example is a test for a feature not yet implemented, or a bug not yet fixed.
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``pytest`` counts and lists *skip* and *xfail* tests separately. Detailed
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information about skipped/xfailed tests is not shown by default to avoid
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cluttering the output. You can use the ``-r`` option to see details
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corresponding to the "short" letters shown in the test progress::
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pytest -rxs # show extra info on skips and xfails
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(See :ref:`how to change command line options defaults`)
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.. _skipif:
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.. _`condition booleans`:
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Skipping test functions
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-----------------------
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.. versionadded:: 2.9
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The simplest way to skip a test function is to mark it with the ``skip`` decorator
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which may be passed an optional ``reason``:
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.. code-block:: python
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@pytest.mark.skip(reason="no way of currently testing this")
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def test_the_unknown():
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...
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Alternatively, it is also possible to skip imperatively during test execution or setup
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by calling the ``pytest.skip(reason)`` function:
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.. code-block:: python
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def test_function():
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if not valid_config():
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pytest.skip("unsupported configuration")
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The imperative method is useful when it is not possible to evaluate the skip condition
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during import time.
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``skipif``
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~~~~~~~~~~
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.. versionadded:: 2.0
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If you wish to skip something conditionally then you can use ``skipif`` instead.
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Here is an example of marking a test function to be skipped
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when run on a Python3.3 interpreter::
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import sys
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@pytest.mark.skipif(sys.version_info < (3,3),
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reason="requires python3.3")
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def test_function():
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...
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If the condition evaluates to ``True`` during collection, the test function will be skipped,
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with the specified reason appearing in the summary when using ``-rs``.
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You can share ``skipif`` markers between modules. Consider this test module::
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# content of test_mymodule.py
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import mymodule
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minversion = pytest.mark.skipif(mymodule.__versioninfo__ < (1,1),
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reason="at least mymodule-1.1 required")
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@minversion
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def test_function():
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...
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You can import the marker and reuse it in another test module::
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# test_myothermodule.py
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from test_mymodule import minversion
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@minversion
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def test_anotherfunction():
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...
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For larger test suites it's usually a good idea to have one file
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where you define the markers which you then consistently apply
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throughout your test suite.
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Alternatively, you can use :ref:`condition strings
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<string conditions>` instead of booleans, but they can't be shared between modules easily
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so they are supported mainly for backward compatibility reasons.
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Skip all test functions of a class or module
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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You can use the ``skipif`` marker (as any other marker) on classes::
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@pytest.mark.skipif(sys.platform == 'win32',
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reason="does not run on windows")
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class TestPosixCalls(object):
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def test_function(self):
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"will not be setup or run under 'win32' platform"
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If the condition is ``True``, this marker will produce a skip result for
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each of the test methods of that class.
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If you want to skip all test functions of a module, you may use
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the ``pytestmark`` name on the global level:
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.. code-block:: python
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# test_module.py
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pytestmark = pytest.mark.skipif(...)
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If multiple ``skipif`` decorators are applied to a test function, it
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will be skipped if any of the skip conditions is true.
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.. _`whole class- or module level`: mark.html#scoped-marking
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Skipping on a missing import dependency
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~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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You can use the following helper at module level
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or within a test or test setup function::
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docutils = pytest.importorskip("docutils")
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If ``docutils`` cannot be imported here, this will lead to a
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skip outcome of the test. You can also skip based on the
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version number of a library::
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docutils = pytest.importorskip("docutils", minversion="0.3")
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The version will be read from the specified
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module's ``__version__`` attribute.
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Summary
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~~~~~~~
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Here's a quick guide on how to skip tests in a module in different situations:
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1. Skip all tests in a module unconditionally:
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.. code-block:: python
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pytestmark = pytest.mark.skip('all tests still WIP')
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2. Skip all tests in a module based on some condition:
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.. code-block:: python
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pytestmark = pytest.mark.skipif(sys.platform == 'win32', 'tests for linux only')
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3. Skip all tests in a module if some import is missing:
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.. code-block:: python
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pexpect = pytest.importorskip('pexpect')
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.. _xfail:
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XFail: mark test functions as expected to fail
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----------------------------------------------
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You can use the ``xfail`` marker to indicate that you
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expect a test to fail::
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@pytest.mark.xfail
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def test_function():
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...
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This test will be run but no traceback will be reported
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when it fails. Instead terminal reporting will list it in the
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"expected to fail" (``XFAIL``) or "unexpectedly passing" (``XPASS``) sections.
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Alternatively, you can also mark a test as ``XFAIL`` from within a test or setup function
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imperatively:
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.. code-block:: python
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def test_function():
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if not valid_config():
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pytest.xfail("failing configuration (but should work)")
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This will unconditionally make ``test_function`` ``XFAIL``. Note that no other code is executed
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after ``pytest.xfail`` call, differently from the marker. That's because it is implemented
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internally by raising a known exception.
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Here's the signature of the ``xfail`` **marker** (not the function), using Python 3 keyword-only
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arguments syntax:
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.. code-block:: python
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def xfail(condition=None, *, reason=None, raises=None, run=True, strict=False):
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``strict`` parameter
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~~~~~~~~~~~~~~~~~~~~
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.. versionadded:: 2.9
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Both ``XFAIL`` and ``XPASS`` don't fail the test suite, unless the ``strict`` keyword-only
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parameter is passed as ``True``:
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.. code-block:: python
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@pytest.mark.xfail(strict=True)
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def test_function():
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...
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This will make ``XPASS`` ("unexpectedly passing") results from this test to fail the test suite.
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You can change the default value of the ``strict`` parameter using the
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``xfail_strict`` ini option:
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.. code-block:: ini
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[pytest]
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xfail_strict=true
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``reason`` parameter
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~~~~~~~~~~~~~~~~~~~~
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As with skipif_ you can also mark your expectation of a failure
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on a particular platform::
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@pytest.mark.xfail(sys.version_info >= (3,3),
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reason="python3.3 api changes")
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def test_function():
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...
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``raises`` parameter
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~~~~~~~~~~~~~~~~~~~~
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If you want to be more specific as to why the test is failing, you can specify
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a single exception, or a list of exceptions, in the ``raises`` argument.
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.. code-block:: python
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@pytest.mark.xfail(raises=RuntimeError)
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def test_function():
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...
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Then the test will be reported as a regular failure if it fails with an
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exception not mentioned in ``raises``.
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``run`` parameter
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~~~~~~~~~~~~~~~~~
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If a test should be marked as xfail and reported as such but should not be
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even executed, use the ``run`` parameter as ``False``:
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.. code-block:: python
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@pytest.mark.xfail(run=False)
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def test_function():
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...
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This is specially useful for xfailing tests that are crashing the interpreter and should be
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investigated later.
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Ignoring xfail
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~~~~~~~~~~~~~~
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By specifying on the commandline::
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pytest --runxfail
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you can force the running and reporting of an ``xfail`` marked test
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as if it weren't marked at all. This also causes ``pytest.xfail`` to produce no effect.
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Examples
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~~~~~~~~
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Here is a simple test file with the several usages:
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.. literalinclude:: example/xfail_demo.py
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Running it with the report-on-xfail option gives this output::
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example $ pytest -rx xfail_demo.py
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======= test session starts ========
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platform linux -- Python 3.x.y, pytest-3.x.y, py-1.x.y, pluggy-0.x.y
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rootdir: $REGENDOC_TMPDIR/example, inifile:
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collected 7 items
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xfail_demo.py xxxxxxx
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======= short test summary info ========
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XFAIL xfail_demo.py::test_hello
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XFAIL xfail_demo.py::test_hello2
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reason: [NOTRUN]
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XFAIL xfail_demo.py::test_hello3
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condition: hasattr(os, 'sep')
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XFAIL xfail_demo.py::test_hello4
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bug 110
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XFAIL xfail_demo.py::test_hello5
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condition: pytest.__version__[0] != "17"
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XFAIL xfail_demo.py::test_hello6
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reason: reason
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XFAIL xfail_demo.py::test_hello7
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======= 7 xfailed in 0.12 seconds ========
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.. _`skip/xfail with parametrize`:
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Skip/xfail with parametrize
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---------------------------
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It is possible to apply markers like skip and xfail to individual
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test instances when using parametrize:
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.. code-block:: python
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import pytest
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@pytest.mark.parametrize(("n", "expected"), [
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(1, 2),
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pytest.param(1, 0, marks=pytest.mark.xfail),
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pytest.param(1, 3, marks=pytest.mark.xfail(reason="some bug")),
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(2, 3),
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(3, 4),
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(4, 5),
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pytest.param(10, 11, marks=pytest.mark.skipif(sys.version_info >= (3, 0), reason="py2k")),
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])
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def test_increment(n, expected):
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assert n + 1 == expected
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.. _string conditions:
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Conditions as strings instead of booleans
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-----------------------------------------
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Prior to pytest-2.4 the only way to specify skipif/xfail conditions was
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to use strings::
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import sys
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@pytest.mark.skipif("sys.version_info >= (3,3)")
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def test_function():
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...
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During test function setup the skipif condition is evaluated by calling
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``eval('sys.version_info >= (3,0)', namespace)``. The namespace contains
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all the module globals, and ``os`` and ``sys`` as a minimum.
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Since pytest-2.4 `condition booleans`_ are considered preferable
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because markers can then be freely imported between test modules.
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With strings you need to import not only the marker but all variables
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used by the marker, which violates encapsulation.
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The reason for specifying the condition as a string was that ``pytest`` can
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report a summary of skip conditions based purely on the condition string.
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With conditions as booleans you are required to specify a ``reason`` string.
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Note that string conditions will remain fully supported and you are free
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to use them if you have no need for cross-importing markers.
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The evaluation of a condition string in ``pytest.mark.skipif(conditionstring)``
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or ``pytest.mark.xfail(conditionstring)`` takes place in a namespace
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dictionary which is constructed as follows:
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* the namespace is initialized by putting the ``sys`` and ``os`` modules
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and the pytest ``config`` object into it.
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* updated with the module globals of the test function for which the
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expression is applied.
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The pytest ``config`` object allows you to skip based on a test
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configuration value which you might have added::
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@pytest.mark.skipif("not config.getvalue('db')")
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def test_function(...):
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...
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The equivalent with "boolean conditions" is::
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@pytest.mark.skipif(not pytest.config.getvalue("db"),
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reason="--db was not specified")
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def test_function(...):
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pass
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.. note::
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You cannot use ``pytest.config.getvalue()`` in code
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imported before pytest's argument parsing takes place. For example,
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``conftest.py`` files are imported before command line parsing and thus
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``config.getvalue()`` will not execute correctly.
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