doc/en/builtin.rst - main - niceSOFT/python3-pytest

doc/en/builtin.rst
279 строк11 KB
Ran Benita
Merge pull request #14627 from pytest-dev/release-9.1.1
19 июн 2026, 14:00
19 июн 2026, 14:004c942a4
:orphan:

.. _`pytest helpers`:

Pytest API and builtin fixtures
================================================


Most of the information of this page has been moved over to :ref:`api-reference`.

For information on plugin hooks and objects, see :ref:`plugins`.

For information on the ``pytest.mark`` mechanism, see :ref:`mark`.

For information about fixtures, see :ref:`fixtures`. To see a complete list of available fixtures (add :option:`-v` to also see fixtures with leading ``_``), type :

.. code-block:: pytest

    $ pytest  --fixtures -v
    =========================== test session starts ============================
    platform linux -- Python 3.x.y, pytest-9.x.y, pluggy-1.x.y -- $PYTHON_PREFIX/bin/python
    cachedir: .pytest_cache
    rootdir: /home/sweet/project
    collected 0 items
    cache -- .../_pytest/cacheprovider.py:560
        Return a cache object that can persist state between testing sessions.

        cache.get(key, default)
        cache.set(key, value)

        Keys must be ``/`` separated strings, where the first part is usually the
        name of your plugin or application to avoid clashes with other cache users.

        Values can be any object handled by the json stdlib module.

    capsys -- .../_pytest/capture.py:1007
        Enable text capturing of writes to ``sys.stdout`` and ``sys.stderr``.

        The captured output is made available via ``capsys.readouterr()`` method
        calls, which return a ``(out, err)`` namedtuple.
        ``out`` and ``err`` will be ``text`` objects.

        Returns an instance of :class:`CaptureFixture[str] <pytest.CaptureFixture>`.

        Example:

        .. code-block:: python

            def test_output(capsys):
                print("hello")
                captured = capsys.readouterr()
                assert captured.out == "hello\n"

    capteesys -- .../_pytest/capture.py:1035
        Enable simultaneous text capturing and pass-through of writes
        to ``sys.stdout`` and ``sys.stderr`` as defined by ``--capture=``.


        The captured output is made available via ``capteesys.readouterr()`` method
        calls, which return a ``(out, err)`` namedtuple.
        ``out`` and ``err`` will be ``text`` objects.

        The output is also passed-through, allowing it to be "live-printed",
        reported, or both as defined by ``--capture=``.

        Returns an instance of :class:`CaptureFixture[str] <pytest.CaptureFixture>`.

        Example:

        .. code-block:: python

            def test_output(capteesys):
                print("hello")
                captured = capteesys.readouterr()
                assert captured.out == "hello\n"

    capsysbinary -- .../_pytest/capture.py:1070
        Enable bytes capturing of writes to ``sys.stdout`` and ``sys.stderr``.

        The captured output is made available via ``capsysbinary.readouterr()``
        method calls, which return a ``(out, err)`` namedtuple.
        ``out`` and ``err`` will be ``bytes`` objects.

        Returns an instance of :class:`CaptureFixture[bytes] <pytest.CaptureFixture>`.

        Example:

        .. code-block:: python

            def test_output(capsysbinary):
                print("hello")
                captured = capsysbinary.readouterr()
                assert captured.out == b"hello\n"

    capfd -- .../_pytest/capture.py:1098
        Enable text capturing of writes to file descriptors ``1`` and ``2``.

        The captured output is made available via ``capfd.readouterr()`` method
        calls, which return a ``(out, err)`` namedtuple.
        ``out`` and ``err`` will be ``text`` objects.

        Returns an instance of :class:`CaptureFixture[str] <pytest.CaptureFixture>`.

        Example:

        .. code-block:: python

            def test_system_echo(capfd):
                os.system('echo "hello"')
                captured = capfd.readouterr()
                assert captured.out == "hello\n"

    capfdbinary -- .../_pytest/capture.py:1126
        Enable bytes capturing of writes to file descriptors ``1`` and ``2``.

        The captured output is made available via ``capfd.readouterr()`` method
        calls, which return a ``(out, err)`` namedtuple.
        ``out`` and ``err`` will be ``byte`` objects.

        Returns an instance of :class:`CaptureFixture[bytes] <pytest.CaptureFixture>`.

        Example:

        .. code-block:: python

            def test_system_echo(capfdbinary):
                os.system('echo "hello"')
                captured = capfdbinary.readouterr()
                assert captured.out == b"hello\n"

    doctest_namespace [session scope] -- .../_pytest/doctest.py:721
        Fixture that returns a :py:class:`dict` that will be injected into the
        namespace of doctests.

        Usually this fixture is used in conjunction with another ``autouse`` fixture:

        .. code-block:: python

            @pytest.fixture(autouse=True)
            def add_np(doctest_namespace):
                doctest_namespace["np"] = numpy

        For more details: :ref:`doctest_namespace`.

    pytestconfig [session scope] -- .../_pytest/fixtures.py:1564
        Session-scoped fixture that returns the session's :class:`pytest.Config`
        object.

        Example::

            def test_foo(pytestconfig):
                if pytestconfig.get_verbosity() > 0:
                    ...

    record_property -- .../_pytest/junitxml.py:275
        Add extra properties to the calling test.

        User properties become part of the test report and are available to the
        configured reporters, like JUnit XML.

        The fixture is callable with ``name, value``. The value is automatically
        XML-encoded.

        Example::

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

    record_xml_attribute -- .../_pytest/junitxml.py:298
        Add extra xml attributes to the tag for the calling test.

        The fixture is callable with ``name, value``. The value is
        automatically XML-encoded.

    record_testsuite_property [session scope] -- .../_pytest/junitxml.py:336
        Record a new ``<property>`` tag as child of the root ``<testsuite>``.

        This is suitable to writing global information regarding the entire test
        suite, and is compatible with ``xunit2`` JUnit family.

        This is a ``session``-scoped fixture which is called with ``(name, value)``. Example:

        .. code-block:: python

            def test_foo(record_testsuite_property):
                record_testsuite_property("ARCH", "PPC")
                record_testsuite_property("STORAGE_TYPE", "CEPH")

        :param name:
            The property name.
        :param value:
            The property value. Will be converted to a string.

        .. warning::

            Currently this fixture **does not work** with the
            `pytest-xdist <https://github.com/pytest-dev/pytest-xdist>`__ plugin. See
            :issue:`7767` for details.

    tmpdir_factory [session scope] -- .../_pytest/legacypath.py:298
        Return a :class:`pytest.TempdirFactory` instance for the test session.

    tmpdir -- .../_pytest/legacypath.py:305
        Return a temporary directory (as `legacy_path`_ object)
        which is unique to each test function invocation.
        The temporary directory is created as a subdirectory
        of the base temporary directory, with configurable retention,
        as discussed in :ref:`temporary directory location and retention`.

        .. note::
            These days, it is preferred to use ``tmp_path``.

            :ref:`About the tmpdir and tmpdir_factory fixtures<tmpdir and tmpdir_factory>`.

        .. _legacy_path: https://py.readthedocs.io/en/latest/path.html

    caplog -- .../_pytest/logging.py:611
        Access and control log capturing.

        Captured logs are available through the following properties/methods::

        * caplog.messages        -> list of format-interpolated log messages
        * caplog.text            -> string containing formatted log output
        * caplog.records         -> list of logging.LogRecord instances
        * caplog.record_tuples   -> list of (logger_name, level, message) tuples
        * caplog.clear()         -> clear captured records and formatted log output string

    monkeypatch -- .../_pytest/monkeypatch.py:36
        A convenient fixture for monkey-patching.

        The fixture provides these methods to modify objects, dictionaries, or
        :data:`os.environ`:

        * :meth:`monkeypatch.setattr(obj, name, value, raising=True) <pytest.MonkeyPatch.setattr>`
        * :meth:`monkeypatch.delattr(obj, name, raising=True) <pytest.MonkeyPatch.delattr>`
        * :meth:`monkeypatch.setitem(mapping, name, value) <pytest.MonkeyPatch.setitem>`
        * :meth:`monkeypatch.delitem(obj, name, raising=True) <pytest.MonkeyPatch.delitem>`
        * :meth:`monkeypatch.setenv(name, value, prepend=None) <pytest.MonkeyPatch.setenv>`
        * :meth:`monkeypatch.delenv(name, raising=True) <pytest.MonkeyPatch.delenv>`
        * :meth:`monkeypatch.syspath_prepend(path) <pytest.MonkeyPatch.syspath_prepend>`
        * :meth:`monkeypatch.chdir(path) <pytest.MonkeyPatch.chdir>`
        * :meth:`monkeypatch.context() <pytest.MonkeyPatch.context>`

        All modifications will be undone after the requesting test function or
        fixture has finished. The ``raising`` parameter determines if a :class:`KeyError`
        or :class:`AttributeError` will be raised if the set/deletion operation does not have the
        specified target.

        To undo modifications done by the fixture in a contained scope,
        use :meth:`context() <pytest.MonkeyPatch.context>`.

    recwarn -- .../_pytest/recwarn.py:37
        Return a :class:`WarningsRecorder` instance that records all warnings emitted by test functions.

        See :ref:`warnings` for information on warning categories.

    subtests -- .../_pytest/subtests.py:136
        Provides subtests functionality.

    tmp_path_factory [session scope] -- .../_pytest/tmpdir.py:276
        Return a :class:`pytest.TempPathFactory` instance for the test session.

    tmp_path -- .../_pytest/tmpdir.py:291
        Return a temporary directory (as :class:`pathlib.Path` object)
        which is unique to each test function invocation.
        The temporary directory is created as a subdirectory
        of the base temporary directory, with configurable retention,
        as discussed in :ref:`temporary directory location and retention`.


    ========================== no tests ran in 0.12s ===========================

You can also interactively ask for help, e.g. by typing on the Python interactive prompt something like:

.. code-block:: python

    import pytest

    help(pytest)