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.. _usage:
Usage and Invocations
==========================================
.. _cmdline:
Calling pytest through ``python -m pytest``
-----------------------------------------------------
You can invoke testing through the Python interpreter from the command line:
.. code-block:: text
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
They are represented by the :class:`pytest.ExitCode` enum. The exit codes being a part of the public API can be imported and accessed directly using:
.. code-block:: python
from pytest import ExitCode
.. note::
If you would like to customize the exit code in some scenarios, specially when
no tests are collected, consider using the
`pytest-custom_exit_code <https://github.com/yashtodi94/pytest-custom_exit_code>`__
plugin.
Getting help on version, option names, environment variables
--------------------------------------------------------------
.. code-block:: bash
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
The full command-line flags can be found in the :ref:`reference <command-line-flags>`.
.. _maxfail:
Stopping after the first (or N) failures
---------------------------------------------------
To stop the testing process after the first (N) failures:
.. code-block:: bash
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**
.. code-block:: bash
pytest test_mod.py
**Run tests in a directory**
.. code-block:: bash
pytest testing/
**Run tests by keyword expressions**
.. code-block:: bash
pytest -k "MyClass and not method"
This will run tests which contain names that match the given *string expression* (case-insensitive),
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:
.. code-block:: bash
pytest test_mod.py::test_func
Another example specifying a test method in the command line:
.. code-block:: bash
pytest test_mod.py::TestClass::test_method
**Run tests by marker expressions**
.. code-block:: bash
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**
.. code-block:: bash
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:
.. code-block:: bash
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.
.. _`pytest.detailed_failed_tests_usage`:
Detailed summary report
-----------------------
The ``-r`` flag can be used to display a "short test summary info" at the end of the test session,
making it easy in large test suites to get a clear picture of all failures, skips, xfails, etc.
It defaults to ``fE`` to list failures and errors.
Example:
.. code-block:: python
# content of test_example.py
import pytest
@pytest.fixture
def error_fixture():
assert 0
def test_ok():
print("ok")
def test_fail():
assert 0
def test_error(error_fixture):
pass
def test_skip():
pytest.skip("skipping this test")
def test_xfail():
pytest.xfail("xfailing this test")
@pytest.mark.xfail(reason="always xfail")
def test_xpass():
pass
.. code-block:: pytest
$ pytest -ra
=========================== test session starts ============================
platform linux -- Python 3.x.y, pytest-6.x.y, py-1.x.y, pluggy-0.x.y
cachedir: $PYTHON_PREFIX/.pytest_cache
rootdir: $REGENDOC_TMPDIR
collected 6 items
test_example.py .FEsxX [100%]
================================== ERRORS ==================================
_______________________ ERROR at setup of test_error _______________________
@pytest.fixture
def error_fixture():
> assert 0
E assert 0
test_example.py:6: AssertionError
================================= FAILURES =================================
________________________________ test_fail _________________________________
def test_fail():
> assert 0
E assert 0
test_example.py:14: AssertionError
========================= short test summary info ==========================
SKIPPED [1] test_example.py:22: skipping this test
XFAIL test_example.py::test_xfail
reason: xfailing this test
XPASS test_example.py::test_xpass always xfail
ERROR test_example.py::test_error - assert 0
FAILED test_example.py::test_fail - assert 0
== 1 failed, 1 passed, 1 skipped, 1 xfailed, 1 xpassed, 1 error in 0.12s ===
The ``-r`` options accepts a number of characters after it, with ``a`` used
above meaning "all except passes".
Here is the full list of available characters that can be used:
- ``f`` - failed
- ``E`` - error
- ``s`` - skipped
- ``x`` - xfailed
- ``X`` - xpassed
- ``p`` - passed
- ``P`` - passed with output
Special characters for (de)selection of groups:
- ``a`` - all except ``pP``
- ``A`` - all
- ``N`` - none, this can be used to display nothing (since ``fE`` is the default)
More than one character can be used, so for example to only see failed and skipped tests, you can execute:
.. code-block:: pytest
$ pytest -rfs
=========================== test session starts ============================
platform linux -- Python 3.x.y, pytest-6.x.y, py-1.x.y, pluggy-0.x.y
cachedir: $PYTHON_PREFIX/.pytest_cache
rootdir: $REGENDOC_TMPDIR
collected 6 items
test_example.py .FEsxX [100%]
================================== ERRORS ==================================
_______________________ ERROR at setup of test_error _______________________
@pytest.fixture
def error_fixture():
> assert 0
E assert 0
test_example.py:6: AssertionError
================================= FAILURES =================================
________________________________ test_fail _________________________________
def test_fail():
> assert 0
E assert 0
test_example.py:14: AssertionError
========================= short test summary info ==========================
FAILED test_example.py::test_fail - assert 0
SKIPPED [1] test_example.py:22: skipping this test
== 1 failed, 1 passed, 1 skipped, 1 xfailed, 1 xpassed, 1 error in 0.12s ===
Using ``p`` lists the passing tests, whilst ``P`` adds an extra section "PASSES" with those tests that passed but had
captured output:
.. code-block:: pytest
$ pytest -rpP
=========================== test session starts ============================
platform linux -- Python 3.x.y, pytest-6.x.y, py-1.x.y, pluggy-0.x.y
cachedir: $PYTHON_PREFIX/.pytest_cache
rootdir: $REGENDOC_TMPDIR
collected 6 items
test_example.py .FEsxX [100%]
================================== ERRORS ==================================
_______________________ ERROR at setup of test_error _______________________
@pytest.fixture
def error_fixture():
> assert 0
E assert 0
test_example.py:6: AssertionError
================================= FAILURES =================================
________________________________ test_fail _________________________________
def test_fail():
> assert 0
E assert 0
test_example.py:14: AssertionError
================================== PASSES ==================================
_________________________________ test_ok __________________________________
--------------------------- Captured stdout call ---------------------------
ok
========================= short test summary info ==========================
PASSED test_example.py::test_ok
== 1 failed, 1 passed, 1 skipped, 1 xfailed, 1 xpassed, 1 error in 0.12s ===
.. _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:
.. code-block:: bash
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:
.. code-block:: bash
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"',)
.. _trace-option:
Dropping to PDB_ (Python Debugger) at the start of a test
----------------------------------------------------------
``pytest`` allows one to drop into the PDB_ prompt immediately at the start of each test via a command line option:
.. code-block:: bash
pytest --trace
This will invoke the Python debugger at the start of every test.
.. _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.
* Output capture gets resumed when ending the debugger session (via the
``continue`` command).
.. _`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.
- With ``--pdb`` passed to pytest, the custom internal Pdb trace UI is used with both ``breakpoint()`` and failed tests/unhandled exceptions.
- ``--pdbcls`` can be used to specify a custom debugger class.
.. _durations:
Profiling test execution duration
-------------------------------------
.. versionchanged:: 6.0
To get a list of the slowest 10 test durations over 1.0s long:
.. code-block:: bash
pytest --durations=10 --durations-min=1.0
By default, pytest will not show test durations that are too small (<0.005s) unless ``-vv`` is passed on the command-line.
.. _faulthandler:
Fault Handler
-------------
.. versionadded:: 5.0
The `faulthandler <https://docs.python.org/3/library/faulthandler.html>`__ standard module
can be used to dump Python tracebacks on a segfault or after a timeout.
The module is automatically enabled for pytest runs, unless the ``-p no:faulthandler`` is given
on the command-line.
Also the :confval:`faulthandler_timeout=X<faulthandler_timeout>` configuration option can be used
to dump the traceback of all threads if a test takes longer than ``X``
seconds to finish (not available on Windows).
.. note::
This functionality has been integrated from the external
`pytest-faulthandler <https://github.com/pytest-dev/pytest-faulthandler>`__ plugin, with two
small differences:
* To disable it, use ``-p no:faulthandler`` instead of ``--no-faulthandler``: the former
can be used with any plugin, so it saves one option.
* The ``--faulthandler-timeout`` command-line option has become the
:confval:`faulthandler_timeout` configuration option. It can still be configured from
the command-line using ``-o faulthandler_timeout=X``.
.. _unraisable:
Warning about unraisable exceptions and unhandled thread exceptions
-------------------------------------------------------------------
.. versionadded:: 6.2
.. note::
These features only work on Python>=3.8.
Unhandled exceptions are exceptions that are raised in a situation in which
they cannot propagate to a caller. The most common case is an exception raised
in a :meth:`__del__ <object.__del__>` implementation.
Unhandled thread exceptions are exceptions raised in a :class:`~threading.Thread`
but not handled, causing the thread to terminate uncleanly.
Both types of exceptions are normally considered bugs, but may go unnoticed
because they don't cause the program itself to crash. Pytest detects these
conditions and issues a warning that is visible in the test run summary.
The plugins are automatically enabled for pytest runs, unless the
``-p no:unraisableexception`` (for unraisable exceptions) and
``-p no:threadexception`` (for thread exceptions) options are given on the
command-line.
The warnings may be silenced selectivly using the :ref:`pytest.mark.filterwarnings ref`
mark. The warning categories are :class:`pytest.PytestUnraisableExceptionWarning` and
:class:`pytest.PytestUnhandledThreadExceptionWarning`.
Creating JUnitXML format files
----------------------------------------------------
To create result files which can be read by Jenkins_ or other Continuous
integration servers, use this invocation:
.. code-block:: bash
pytest --junitxml=path
to create an XML file at ``path``.
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
.. versionadded:: 4.0
JUnit XML specification seems to indicate that ``"time"`` attribute
should report total test execution times, including setup and teardown
(`1 <http://windyroad.com.au/dl/Open%20Source/JUnit.xsd>`_, `2
<https://www.ibm.com/support/knowledgecenter/en/SSQ2R2_14.1.0/com.ibm.rsar.analysis.codereview.cobol.doc/topics/cac_useresults_junit.html>`_).
It is the default pytest behavior. To report just call durations
instead, configure the ``junit_duration_report`` option like this:
.. code-block:: ini
[pytest]
junit_duration_report = call
.. _record_property example:
record_property
^^^^^^^^^^^^^^^
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::
Please note that using this feature will break schema verifications for the latest JUnitXML schema.
This might be a problem when used with some CI servers.
record_xml_attribute
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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>
.. warning::
Please note that using this feature will break schema verifications for the latest JUnitXML schema.
This might be a problem when used with some CI servers.
.. _record_testsuite_property example:
record_testsuite_property
^^^^^^^^^^^^^^^^^^^^^^^^^
.. versionadded:: 4.5
If you want to add a properties node at the test-suite level, which may contains properties
that are relevant to all tests, you can use the ``record_testsuite_property`` session-scoped fixture:
The ``record_testsuite_property`` session-scoped fixture can be used to add properties relevant
to all tests.
.. code-block:: python
import pytest
@pytest.fixture(scope="session", autouse=True)
def log_global_env_facts(record_testsuite_property):
record_testsuite_property("ARCH", "PPC")
record_testsuite_property("STORAGE_TYPE", "CEPH")
class TestMe:
def test_foo(self):
assert True
The fixture is a callable which receives ``name`` and ``value`` of a ``<property>`` tag
added at the test-suite level of the generated xml:
.. code-block:: xml
<testsuite errors="0" failures="0" name="pytest" skipped="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>
``name`` must be a string, ``value`` will be converted to a string and properly xml-escaped.
The generated XML is compatible with the latest ``xunit`` standard, contrary to `record_property`_
and `record_xml_attribute`_.
Creating resultlog format files
----------------------------------------------------
To create plain-text machine-readable result files you can issue:
.. code-block:: bash
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.
.. warning::
This option is rarely used and is scheduled for removal in pytest 6.0.
If you use this option, consider using the new `pytest-reportlog <https://github.com/pytest-dev/pytest-reportlog>`__ plugin instead.
See `the deprecation docs <https://docs.pytest.org/en/stable/deprecations.html#result-log-result-log>`__
for more information.
.. _`PyPy-test`: http://buildbot.pypy.org/summary
Sending test report to online pastebin service
-----------------------------------------------------
**Creating a URL for each test failure**:
.. code-block:: bash
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**:
.. code-block:: bash
pytest --pastebin=all
Currently only pasting to the http://bpaste.net service is implemented.
.. versionchanged:: 5.2
If creating the URL fails for any reason, a warning is generated instead of failing the
entire test suite.
Early loading plugins
---------------------
You can early-load plugins (internal and external) explicitly in the command-line with the ``-p`` option::
pytest -p mypluginmodule
The option receives a ``name`` parameter, which can be:
* A full module dotted name, for example ``myproject.plugins``. This dotted name must be importable.
* The entry-point name of a plugin. This is the name passed to ``setuptools`` when the plugin is
registered. For example to early-load the `pytest-cov <https://pypi.org/project/pytest-cov/>`__ plugin you can use::
pytest -p pytest_cov
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:
.. code-block:: bash
pytest -p no:doctest
.. _`pytest.main-usage`:
Calling pytest from Python code
----------------------------------------------------
You can invoke ``pytest`` from Python code directly:
.. code-block:: python
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:
.. code-block:: python
pytest.main(["-x", "mytestdir"])
You can specify additional plugins to ``pytest.main``:
.. code-block:: python
# content of myinvoke.py
import pytest
class MyPlugin:
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:
.. code-block:: pytest
$ python myinvoke.py
.FEsxX. [100%]*** test run reporting finishing
================================== ERRORS ==================================
_______________________ ERROR at setup of test_error _______________________
@pytest.fixture
def error_fixture():
> assert 0
E assert 0
test_example.py:6: AssertionError
================================= FAILURES =================================
________________________________ test_fail _________________________________
def test_fail():
> assert 0
E assert 0
test_example.py:14: AssertionError
========================= short test summary info ==========================
FAILED test_example.py::test_fail - assert 0
ERROR test_example.py::test_error - assert 0
.. 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.
.. _jenkins: http://jenkins-ci.org/
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