Pytest API and builtin fixtures¶
Most of the information of this page has been moved over to API Reference.
For information on plugin hooks and objects, see Writing plugins.
For information on the pytest.mark mechanism, see 如何用属性标记测试函数.
For information about fixtures, see Fixtures reference. To see a complete list of available fixtures (add -v to also see fixtures with leading _), type :
$ pytest --fixtures -v
=========================== test session starts ============================
platform linux -- Python 3.x.y, pytest-7.x.y, pluggy-1.x.y -- $PYTHON_PREFIX/bin/python
cachedir: .pytest_cache
rootdir: /home/sweet/project
collected 0 items
cache -- .../_pytest/cacheprovider.py:510
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:878
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"
capsysbinary -- .../_pytest/capture.py:906
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:934
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:962
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:735
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:1344
Session-scoped fixture that returns the session's :class:`pytest.Config`
object.
Example::
def test_foo(pytestconfig):
if pytestconfig.getoption("verbose") > 0:
...
record_property -- .../_pytest/junitxml.py:282
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:305
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:343
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")
``name`` must be a string, ``value`` will be converted to a string and properly xml-escaped.
.. 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:302
Return a :class:`pytest.TempdirFactory` instance for the test session.
tmpdir -- .../_pytest/legacypath.py:309
Return a temporary directory path object which is unique to each test
function invocation, created as a sub directory of the base temporary
directory.
By default, a new base temporary directory is created each test session,
and old bases are removed after 3 sessions, to aid in debugging. If
``--basetemp`` is used then it is cleared each session. See :ref:`base
temporary directory`.
The returned object is a `legacy_path`_ object.
.. 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:487
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:29
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:29
Return a :class:`WarningsRecorder` instance that records all warnings emitted by test functions.
See https://docs.python.org/library/how-to/capture-warnings.html for information
on warning categories.
tmp_path_factory [session scope] -- .../_pytest/tmpdir.py:184
Return a :class:`pytest.TempPathFactory` instance for the test session.
tmp_path -- .../_pytest/tmpdir.py:199
Return a temporary directory path object which is unique to each test
function invocation, created as a sub directory of the base temporary
directory.
By default, a new base temporary directory is created each test session,
and old bases are removed after 3 sessions, to aid in debugging. If
``--basetemp`` is used then it is cleared each session. See :ref:`base
temporary directory`.
The returned object is a :class:`pathlib.Path` object.
========================== no tests ran in 0.12s ===========================
You can also interactively ask for help, e.g. by typing on the Python interactive prompt something like:
import pytest
help(pytest)
