third_party/blink/web_tests/external/wpt/tools/third_party/pytest/doc/en/usage.rst

.. _usage:

Usage and Invocations
==========================================


.. _cmdline:

Calling pytest through ``python -m pytest``
-----------------------------------------------------

.. versionadded:: 2.0

You can invoke testing through the Python interpreter from the command line::

    python -m pytest [...]

This is almost equivalent to invoking the command line script ``pytest [...]``
directly, except that calling via ``python`` will also add the current directory to ``sys.path``.

Possible exit codes
--------------------------------------------------------------

Running ``pytest`` can result in six different exit codes:

:Exit code 0: All tests were collected and passed successfully
:Exit code 1: Tests were collected and run but some of the tests failed
:Exit code 2: Test execution was interrupted by the user
:Exit code 3: Internal error happened while executing tests
:Exit code 4: pytest command line usage error
:Exit code 5: No tests were collected

Getting help on version, option names, environment variables
--------------------------------------------------------------

::

    pytest --version   # shows where pytest was imported from
    pytest --fixtures  # show available builtin function arguments
    pytest -h | --help # show help on command line and config file options


.. _maxfail:

Stopping after the first (or N) failures
---------------------------------------------------

To stop the testing process after the first (N) failures::

    pytest -x            # stop after first failure
    pytest --maxfail=2    # stop after two failures

.. _select-tests:

Specifying tests / selecting tests
---------------------------------------------------

Pytest supports several ways to run and select tests from the command-line.

**Run tests in a module**

::

    pytest test_mod.py

**Run tests in a directory**

::

    pytest testing/

**Run tests by keyword expressions**

::

    pytest -k "MyClass and not method"

This will run tests which contain names that match the given *string expression*, which can
include Python operators that use filenames, class names and function names as variables.
The example above will run ``TestMyClass.test_something``  but not ``TestMyClass.test_method_simple``.

.. _nodeids:

**Run tests by node ids**

Each collected test is assigned a unique ``nodeid`` which consist of the module filename followed
by specifiers like class names, function names and parameters from parametrization, separated by ``::`` characters.

To run a specific test within a module::

    pytest test_mod.py::test_func


Another example specifying a test method in the command line::

    pytest test_mod.py::TestClass::test_method

**Run tests by marker expressions**

::

    pytest -m slow

Will run all tests which are decorated with the ``@pytest.mark.slow`` decorator.

For more information see :ref:`marks <mark>`.

**Run tests from packages**

::

    pytest --pyargs pkg.testing

This will import ``pkg.testing`` and use its filesystem location to find and run tests from.


Modifying Python traceback printing
----------------------------------------------

Examples for modifying traceback printing::

    pytest --showlocals # show local variables in tracebacks
    pytest -l           # show local variables (shortcut)

    pytest --tb=auto    # (default) 'long' tracebacks for the first and last
                         # entry, but 'short' style for the other entries
    pytest --tb=long    # exhaustive, informative traceback formatting
    pytest --tb=short   # shorter traceback format
    pytest --tb=line    # only one line per failure
    pytest --tb=native  # Python standard library formatting
    pytest --tb=no      # no traceback at all

The ``--full-trace`` causes very long traces to be printed on error (longer
than ``--tb=long``). It also ensures that a stack trace is printed on
**KeyboardInterrupt** (Ctrl+C).
This is very useful if the tests are taking too long and you interrupt them
with Ctrl+C to find out where the tests are *hanging*. By default no output
will be shown (because KeyboardInterrupt is caught by pytest). By using this
option you make sure a trace is shown.


.. _pdb-option:

Dropping to PDB_ (Python Debugger) on failures
-----------------------------------------------

.. _PDB: http://docs.python.org/library/pdb.html

Python comes with a builtin Python debugger called PDB_.  ``pytest``
allows one to drop into the PDB_ prompt via a command line option::

    pytest --pdb

This will invoke the Python debugger on every failure (or KeyboardInterrupt).
Often you might only want to do this for the first failing test to understand
a certain failure situation::

    pytest -x --pdb   # drop to PDB on first failure, then end test session
    pytest --pdb --maxfail=3  # drop to PDB for first three failures

Note that on any failure the exception information is stored on
``sys.last_value``, ``sys.last_type`` and ``sys.last_traceback``. In
interactive use, this allows one to drop into postmortem debugging with
any debug tool. One can also manually access the exception information,
for example::

    >>> import sys
    >>> sys.last_traceback.tb_lineno
    42
    >>> sys.last_value
    AssertionError('assert result == "ok"',)

.. _breakpoints:

Setting breakpoints
-------------------

.. versionadded: 2.4.0

To set a breakpoint in your code use the native Python ``import pdb;pdb.set_trace()`` call
in your code and pytest automatically disables its output capture for that test:

* Output capture in other tests is not affected.
* Any prior test output that has already been captured and will be processed as
  such.
* Any later output produced within the same test will not be captured and will
  instead get sent directly to ``sys.stdout``. Note that this holds true even
  for test output occurring after you exit the interactive PDB_ tracing session
  and continue with the regular test run.


.. _`breakpoint-builtin`:

Using the builtin breakpoint function
-------------------------------------

Python 3.7 introduces a builtin ``breakpoint()`` function.
Pytest supports the use of ``breakpoint()`` with the following behaviours:

 - When ``breakpoint()`` is called and ``PYTHONBREAKPOINT`` is set to the default value, pytest will use the custom internal PDB trace UI instead of the system default ``Pdb``.
 - When tests are complete, the system will default back to the system ``Pdb`` trace UI.
 - If ``--pdb`` is called on execution of pytest, the custom internal Pdb trace UI is used on ``bothbreakpoint()`` and failed tests/unhandled exceptions.
 - If ``--pdbcls`` is used, the custom class debugger will be executed when a test fails (as expected within existing behaviour), but also when ``breakpoint()`` is called from within a test, the custom class debugger will be instantiated.

.. _durations:

Profiling test execution duration
-------------------------------------

.. versionadded: 2.2

To get a list of the slowest 10 test durations::

    pytest --durations=10


Creating JUnitXML format files
----------------------------------------------------

To create result files which can be read by Jenkins_ or other Continuous
integration servers, use this invocation::

    pytest --junitxml=path

to create an XML file at ``path``.

.. versionadded:: 3.1

To set the name of the root test suite xml item, you can configure the ``junit_suite_name`` option in your config file:

.. code-block:: ini

    [pytest]
    junit_suite_name = my_suite

.. _record_property example:

record_property
^^^^^^^^^^^^^^^

.. versionadded:: 2.8
.. versionchanged:: 3.5

   Fixture renamed from ``record_xml_property`` to ``record_property`` as user
   properties are now available to all reporters.
   ``record_xml_property`` is now deprecated.

If you want to log additional information for a test, you can use the
``record_property`` fixture:

.. code-block:: python

    def test_function(record_property):
        record_property("example_key", 1)
        assert True

This will add an extra property ``example_key="1"`` to the generated
``testcase`` tag:

.. code-block:: xml

    <testcase classname="test_function" file="test_function.py" line="0" name="test_function" time="0.0009">
      <properties>
        <property name="example_key" value="1" />
      </properties>
    </testcase>

Alternatively, you can integrate this functionality with custom markers:

.. code-block:: python

    # content of conftest.py


    def pytest_collection_modifyitems(session, config, items):
        for item in items:
            for marker in item.iter_markers(name="test_id"):
                test_id = marker.args[0]
                item.user_properties.append(("test_id", test_id))

And in your tests:

.. code-block:: python

    # content of test_function.py
    import pytest


    @pytest.mark.test_id(1501)
    def test_function():
        assert True

Will result in:

.. code-block:: xml

    <testcase classname="test_function" file="test_function.py" line="0" name="test_function" time="0.0009">
      <properties>
        <property name="test_id" value="1501" />
      </properties>
    </testcase>

.. warning::

    ``record_property`` is an experimental feature and may change in the future.

    Also please note that using this feature will break any schema verification.
    This might be a problem when used with some CI servers.

record_xml_attribute
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.4

To add an additional xml attribute to a testcase element, you can use
``record_xml_attribute`` fixture. This can also be used to override existing values:

.. code-block:: python

    def test_function(record_xml_attribute):
        record_xml_attribute("assertions", "REQ-1234")
        record_xml_attribute("classname", "custom_classname")
        print("hello world")
        assert True

Unlike ``record_property``, this will not add a new child element.
Instead, this will add an attribute ``assertions="REQ-1234"`` inside the generated
``testcase`` tag and override the default ``classname`` with ``"classname=custom_classname"``:

.. code-block:: xml

    <testcase classname="custom_classname" file="test_function.py" line="0" name="test_function" time="0.003" assertions="REQ-1234">
        <system-out>
            hello world
        </system-out>
    </testcase>

.. warning::

    ``record_xml_attribute`` is an experimental feature, and its interface might be replaced
    by something more powerful and general in future versions. The
    functionality per-se will be kept, however.

    Using this over ``record_xml_property`` can help when using ci tools to parse the xml report.
    However, some parsers are quite strict about the elements and attributes that are allowed.
    Many tools use an xsd schema (like the example below) to validate incoming xml.
    Make sure you are using attribute names that are allowed by your parser.

    Below is the Scheme used by Jenkins to validate the XML report:

    .. code-block:: xml

        <xs:element name="testcase">
            <xs:complexType>
                <xs:sequence>
                    <xs:element ref="skipped" minOccurs="0" maxOccurs="1"/>
                    <xs:element ref="error" minOccurs="0" maxOccurs="unbounded"/>
                    <xs:element ref="failure" minOccurs="0" maxOccurs="unbounded"/>
                    <xs:element ref="system-out" minOccurs="0" maxOccurs="unbounded"/>
                    <xs:element ref="system-err" minOccurs="0" maxOccurs="unbounded"/>
                </xs:sequence>
                <xs:attribute name="name" type="xs:string" use="required"/>
                <xs:attribute name="assertions" type="xs:string" use="optional"/>
                <xs:attribute name="time" type="xs:string" use="optional"/>
                <xs:attribute name="classname" type="xs:string" use="optional"/>
                <xs:attribute name="status" type="xs:string" use="optional"/>
            </xs:complexType>
        </xs:element>

LogXML: add_global_property
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

.. versionadded:: 3.0

If you want to add a properties node in the testsuite level, which may contains properties that are relevant
to all testcases you can use ``LogXML.add_global_properties``

.. code-block:: python

    import pytest


    @pytest.fixture(scope="session")
    def log_global_env_facts(f):

        if pytest.config.pluginmanager.hasplugin("junitxml"):
            my_junit = getattr(pytest.config, "_xml", None)

        my_junit.add_global_property("ARCH", "PPC")
        my_junit.add_global_property("STORAGE_TYPE", "CEPH")


    @pytest.mark.usefixtures(log_global_env_facts.__name__)
    def start_and_prepare_env():
        pass


    class TestMe(object):
        def test_foo(self):
            assert True

This will add a property node below the testsuite node to the generated xml:

.. code-block:: xml

    <testsuite errors="0" failures="0" name="pytest" skips="0" tests="1" time="0.006">
      <properties>
        <property name="ARCH" value="PPC"/>
        <property name="STORAGE_TYPE" value="CEPH"/>
      </properties>
      <testcase classname="test_me.TestMe" file="test_me.py" line="16" name="test_foo" time="0.000243663787842"/>
    </testsuite>

.. warning::

    This is an experimental feature, and its interface might be replaced
    by something more powerful and general in future versions. The
    functionality per-se will be kept.

Creating resultlog format files
----------------------------------------------------

.. deprecated:: 3.0

    This option is rarely used and is scheduled for removal in 4.0.

    An alternative for users which still need similar functionality is to use the
    `pytest-tap <https://pypi.org/project/pytest-tap/>`_ plugin which provides
    a stream of test data.

    If you have any concerns, please don't hesitate to
    `open an issue <https://github.com/pytest-dev/pytest/issues>`_.

To create plain-text machine-readable result files you can issue::

    pytest --resultlog=path

and look at the content at the ``path`` location.  Such files are used e.g.
by the `PyPy-test`_ web page to show test results over several revisions.

.. _`PyPy-test`: http://buildbot.pypy.org/summary


Sending test report to online pastebin service
-----------------------------------------------------

**Creating a URL for each test failure**::

    pytest --pastebin=failed

This will submit test run information to a remote Paste service and
provide a URL for each failure.  You may select tests as usual or add
for example ``-x`` if you only want to send one particular failure.

**Creating a URL for a whole test session log**::

    pytest --pastebin=all

Currently only pasting to the http://bpaste.net service is implemented.

Disabling plugins
-----------------

To disable loading specific plugins at invocation time, use the ``-p`` option
together with the prefix ``no:``.

Example: to disable loading the plugin ``doctest``, which is responsible for
executing doctest tests from text files, invoke pytest like this::

    pytest -p no:doctest

.. _`pytest.main-usage`:

Calling pytest from Python code
----------------------------------------------------

.. versionadded:: 2.0

You can invoke ``pytest`` from Python code directly::

    pytest.main()

this acts as if you would call "pytest" from the command line.
It will not raise ``SystemExit`` but return the exitcode instead.
You can pass in options and arguments::

    pytest.main(['-x', 'mytestdir'])

You can specify additional plugins to ``pytest.main``::

    # content of myinvoke.py
    import pytest
    class MyPlugin(object):
        def pytest_sessionfinish(self):
            print("*** test run reporting finishing")

    pytest.main(["-qq"], plugins=[MyPlugin()])

Running it will show that ``MyPlugin`` was added and its
hook was invoked::

    $ python myinvoke.py
    .                                                                    [100%]*** test run reporting finishing


.. note::

    Calling ``pytest.main()`` will result in importing your tests and any modules
    that they import. Due to the caching mechanism of python's import system,
    making subsequent calls to ``pytest.main()`` from the same process will not
    reflect changes to those files between the calls. For this reason, making
    multiple calls to ``pytest.main()`` from the same process (in order to re-run
    tests, for example) is not recommended.


.. include:: links.inc