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Make it clear that pytest.xfail stops the test 

Also did a general review of the document to improve the flow

Fix #810
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Bruno Oliveira 2017-05-31 19:51:47 -03:00
parent cca4de20cf
commit 409d2f1d54
2 changed files with 121 additions and 119 deletions
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@ -0,0 +1 @@
Make it clear that ``pytest.xfail`` stops test execution at the calling point and improve overall flow of the ``skipping`` docs.

239
doc/en/skipping.rst
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@ -5,14 +5,17 @@
Skip and xfail: dealing with tests that cannot succeed
=====================================================================
If you have test functions that cannot be run on certain platforms
or that you expect to fail you can mark them accordingly or you
may call helper functions during execution of setup or test functions.
You can mark test functions that cannot be run on certain platforms
or that you expect to fail so pytest can deal with them accordingly and
present a summary of the test session, while keeping the test suite *green*.
A *skip* means that you expect your test to pass unless the environment
(e.g. wrong Python interpreter, missing dependency) prevents it to run.
And *xfail* means that your test can run but you expect it to fail
because there is an implementation problem.
A **skip** means that you expect your test to pass only if some conditions are met,
otherwise pytest should skip running the test altogether. Common examples are skipping
windows-only tests on non-windows platforms, or skipping tests that depend on an external
resource which is not available at the moment (for example a database).
A **xfail** means that you expect a test to fail for some reason.
A common example is a test for a feature not yet implemented, or a bug not yet fixed.
``pytest`` counts and lists *skip* and *xfail* tests separately. Detailed
information about skipped/xfailed tests is not shown by default to avoid
@ -26,8 +29,8 @@ corresponding to the "short" letters shown in the test progress::
.. _skipif:
.. _`condition booleans`:
Marking a test function to be skipped
-------------------------------------------
Skipping test functions
-----------------------
.. versionadded:: 2.9
@ -40,10 +43,23 @@ which may be passed an optional ``reason``:
def test_the_unknown():
...
Alternatively, it is also possible to skip imperatively during test execution or setup
by calling the ``pytest.skip(reason)`` function:
.. code-block:: python
def test_function():
if not valid_config():
pytest.skip("unsupported configuration")
The imperative method is useful when it is not possible to evaluate the skip condition
during import time.
``skipif``
~~~~~~~~~~
.. versionadded:: 2.0, 2.4
.. versionadded:: 2.0
If you wish to skip something conditionally then you can use ``skipif`` instead.
Here is an example of marking a test function to be skipped
@ -55,16 +71,12 @@ when run on a Python3.3 interpreter::
def test_function():
...
During test function setup the condition ("sys.version_info >= (3,3)") is
checked. If it evaluates to True, the test function will be skipped
with the specified reason. Note that pytest enforces specifying a reason
in order to report meaningful "skip reasons" (e.g. when using ``-rs``).
If the condition is a string, it will be evaluated as python expression.
If the condition evaluates to ``True`` during collection, the test function will be skipped,
with the specified reason appearing in the summary when using ``-rs``.
You can share skipif markers between modules. Consider this test module::
You can share ``skipif`` markers between modules. Consider this test module::
# content of test_mymodule.py
import mymodule
minversion = pytest.mark.skipif(mymodule.__versioninfo__ < (1,1),
reason="at least mymodule-1.1 required")
@ -72,7 +84,7 @@ You can share skipif markers between modules. Consider this test module::
def test_function():
...
You can import it from another test module::
You can import the marker and reuse it in another test module::
# test_myothermodule.py
from test_mymodule import minversion
@ -85,16 +97,15 @@ For larger test suites it's usually a good idea to have one file
where you define the markers which you then consistently apply
throughout your test suite.
Alternatively, the pre pytest-2.4 way to specify :ref:`condition strings
<string conditions>` instead of booleans will remain fully supported in future
versions of pytest. It couldn't be easily used for importing markers
between test modules so it's no longer advertised as the primary method.
Alternatively, you can use :ref:`condition strings
<string conditions>` instead of booleans, but they can't be shared between modules easily
so they are supported mainly for backward compatibility reasons.
Skip all test functions of a class or module
---------------------------------------------
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can use the ``skipif`` decorator (and any other marker) on classes::
You can use the ``skipif`` marker (as any other marker) on classes::
@pytest.mark.skipif(sys.platform == 'win32',
reason="does not run on windows")
@ -103,10 +114,10 @@ You can use the ``skipif`` decorator (and any other marker) on classes::
def test_function(self):
"will not be setup or run under 'win32' platform"
If the condition is true, this marker will produce a skip result for
each of the test methods.
If the condition is ``True``, this marker will produce a skip result for
each of the test methods of that class.
If you want to skip all test functions of a module, you must use
If you want to skip all test functions of a module, you may use
the ``pytestmark`` name on the global level:
.. code-block:: python
@ -114,15 +125,57 @@ the ``pytestmark`` name on the global level:
# test_module.py
pytestmark = pytest.mark.skipif(...)
If multiple "skipif" decorators are applied to a test function, it
If multiple ``skipif`` decorators are applied to a test function, it
will be skipped if any of the skip conditions is true.
.. _`whole class- or module level`: mark.html#scoped-marking
Skipping on a missing import dependency
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
You can use the following helper at module level
or within a test or test setup function::
docutils = pytest.importorskip("docutils")
If ``docutils`` cannot be imported here, this will lead to a
skip outcome of the test. You can also skip based on the
version number of a library::
docutils = pytest.importorskip("docutils", minversion="0.3")
The version will be read from the specified
module's ``__version__`` attribute.
Summary
~~~~~~~
Here's a quick guide on how to skip tests in a module in different situations:
1. Skip all tests in a module unconditionally:
.. code-block:: python
pytestmark = pytest.mark.skip('all tests still WIP')
2. Skip all tests in a module based on some condition:
.. code-block:: python
pytestmark = pytest.mark.skipif(sys.platform == 'win32', 'tests for linux only')
3. Skip all tests in a module if some import is missing:
.. code-block:: python
pexpect = pytest.importorskip('pexpect')
.. _xfail:
Mark a test function as expected to fail
-------------------------------------------------------
XFail: mark test functions as expected to fail
----------------------------------------------
You can use the ``xfail`` marker to indicate that you
expect a test to fail::
@ -135,6 +188,29 @@ This test will be run but no traceback will be reported
when it fails. Instead terminal reporting will list it in the
"expected to fail" (``XFAIL``) or "unexpectedly passing" (``XPASS``) sections.
Alternatively, you can also mark a test as ``XFAIL`` from within a test or setup function
imperatively:
.. code-block:: python
def test_function():
if not valid_config():
pytest.xfail("failing configuration (but should work)")
This will unconditionally make ``test_function`` ``XFAIL``. Note that no other code is executed
after ``pytest.xfail`` call, differently from the marker. That's because it is implemented
internally by raising a known exception.
Here's the signature of the ``xfail`` **marker** (not the function), using Python 3 keyword-only
arguments syntax:
.. code-block:: python
def xfail(condition=None, *, reason=None, raises=None, run=True, strict=False):
``strict`` parameter
~~~~~~~~~~~~~~~~~~~~
@ -200,18 +276,19 @@ even executed, use the ``run`` parameter as ``False``:
def test_function():
...
This is specially useful for marking crashing tests for later inspection.
This is specially useful for xfailing tests that are crashing the interpreter and should be
investigated later.
Ignoring xfail marks
~~~~~~~~~~~~~~~~~~~~
Ignoring xfail
~~~~~~~~~~~~~~
By specifying on the commandline::
pytest --runxfail
you can force the running and reporting of an ``xfail`` marked test
as if it weren't marked at all.
as if it weren't marked at all. This also causes ``pytest.xfail`` to produce no effect.
Examples
~~~~~~~~
@ -245,16 +322,6 @@ Running it with the report-on-xfail option gives this output::
======= 7 xfailed in 0.12 seconds ========
xfail signature summary
~~~~~~~~~~~~~~~~~~~~~~~
Here's the signature of the ``xfail`` marker, using Python 3 keyword-only
arguments syntax:
.. code-block:: python
def xfail(condition=None, *, reason=None, raises=None, run=True, strict=False):
.. _`skip/xfail with parametrize`:
@ -263,73 +330,29 @@ Skip/xfail with parametrize
---------------------------
It is possible to apply markers like skip and xfail to individual
test instances when using parametrize::
test instances when using parametrize:
.. code-block:: python
import pytest
@pytest.mark.parametrize(("n", "expected"), [
(1, 2),
pytest.mark.xfail((1, 0)),
pytest.mark.xfail(reason="some bug")((1, 3)),
pytest.param(1, 0, marks=pytest.mark.xfail),
pytest.param(1, 3, marks=pytest.mark.xfail(reason="some bug")),
(2, 3),
(3, 4),
(4, 5),
pytest.mark.skipif("sys.version_info >= (3,0)")((10, 11)),
pytest.param(10, 11, marks=pytest.mark.skipif(sys.version_info >= (3, 0), reason="py2k")),
])
def test_increment(n, expected):
assert n + 1 == expected
Imperative xfail from within a test or setup function
------------------------------------------------------
If you cannot declare xfail- of skipif conditions at import
time you can also imperatively produce an according outcome
imperatively, in test or setup code::
def test_function():
if not valid_config():
pytest.xfail("failing configuration (but should work)")
# or
pytest.skip("unsupported configuration")
Note that calling ``pytest.skip`` at the module level
is not allowed since pytest 3.0. If you are upgrading
and ``pytest.skip`` was being used at the module level, you can set a
``pytestmark`` variable:
.. code-block:: python
# before pytest 3.0
pytest.skip('skipping all tests because of reasons')
# after pytest 3.0
pytestmark = pytest.mark.skip('skipping all tests because of reasons')
``pytestmark`` applies a mark or list of marks to all tests in a module.
Skipping on a missing import dependency
--------------------------------------------------
You can use the following import helper at module level
or within a test or test setup function::
docutils = pytest.importorskip("docutils")
If ``docutils`` cannot be imported here, this will lead to a
skip outcome of the test. You can also skip based on the
version number of a library::
docutils = pytest.importorskip("docutils", minversion="0.3")
The version will be read from the specified
module's ``__version__`` attribute.
.. _string conditions:
specifying conditions as strings versus booleans
----------------------------------------------------------
Conditions as strings instead of booleans
-----------------------------------------
Prior to pytest-2.4 the only way to specify skipif/xfail conditions was
to use strings::
@ -346,7 +369,7 @@ all the module globals, and ``os`` and ``sys`` as a minimum.
Since pytest-2.4 `condition booleans`_ are considered preferable
because markers can then be freely imported between test modules.
With strings you need to import not only the marker but all variables
everything used by the marker, which violates encapsulation.
used by the marker, which violates encapsulation.
The reason for specifying the condition as a string was that ``pytest`` can
report a summary of skip conditions based purely on the condition string.
@ -387,25 +410,3 @@ The equivalent with "boolean conditions" is::
``config.getvalue()`` will not execute correctly.
Summary
-------
Here's a quick guide on how to skip tests in a module in different situations:
1. Skip all tests in a module unconditionally:
.. code-block:: python
pytestmark = pytest.mark.skip('all tests still WIP')
2. Skip all tests in a module based on some condition:
.. code-block:: python
pytestmark = pytest.mark.skipif(sys.platform == 'win32', 'tests for linux only')
3. Skip all tests in a module if some import is missing:
.. code-block:: python
pexpect = pytest.importorskip('pexpect')