| Current File : //usr/share/doc/pytest-2.7.0/html/en/_sources/usage.txt |
.. _usage:
Usage and Invocations
==========================================
.. _cmdline:
Calling pytest through ``python -m pytest``
-----------------------------------------------------
.. versionadded:: 2.0
If you use Python-2.5 or later you can invoke testing through the
Python interpreter from the command line::
python -m pytest [...]
This is equivalent to invoking the command line script ``py.test [...]``
directly.
Getting help on version, option names, environment variables
--------------------------------------------------------------
::
py.test --version # shows where pytest was imported from
py.test --fixtures # show available builtin function arguments
py.test -h | --help # show help on command line and config file options
Stopping after the first (or N) failures
---------------------------------------------------
To stop the testing process after the first (N) failures::
py.test -x # stop after first failure
py.test --maxfail=2 # stop after two failures
Specifying tests / selecting tests
---------------------------------------------------
Several test run options::
py.test test_mod.py # run tests in module
py.test somepath # run all tests below somepath
py.test -k stringexpr # only run tests with names that match the
# the "string expression", e.g. "MyClass and not method"
# will select TestMyClass.test_something
# but not TestMyClass.test_method_simple
py.test test_mod.py::test_func # only run tests that match the "node ID",
# e.g "test_mod.py::test_func" will select
# only test_func in test_mod.py
Import 'pkg' and use its filesystem location to find and run tests::
py.test --pyargs pkg # run all tests found below directory of pypkg
Modifying Python traceback printing
----------------------------------------------
Examples for modifying traceback printing::
py.test --showlocals # show local variables in tracebacks
py.test -l # show local variables (shortcut)
py.test --tb=long # the default informative traceback formatting
py.test --tb=native # the Python standard library formatting
py.test --tb=short # a shorter traceback format
py.test --tb=line # only one line per failure
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::
py.test --pdb
This will invoke the Python debugger on every failure. Often you might
only want to do this for the first failing test to understand a certain
failure situation::
py.test -x --pdb # drop to PDB on first failure, then end test session
py.test --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"',)
Setting a breakpoint / aka ``set_trace()``
----------------------------------------------------
If you want to set a breakpoint and enter the ``pdb.set_trace()`` you
can use a helper::
import pytest
def test_function():
...
pytest.set_trace() # invoke PDB debugger and tracing
.. versionadded: 2.0.0
Prior to pytest version 2.0.0 you could only enter PDB_ tracing if you disabled
capturing on the command line via ``py.test -s``. In later versions, pytest
automatically disables its output capture when you enter PDB_ tracing:
* 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 occuring after you exit the interactive PDB_ tracing session
and continue with the regular test run.
.. versionadded: 2.4.0
Since pytest version 2.4.0 you can also use the native Python
``import pdb;pdb.set_trace()`` call to enter PDB_ tracing without having to use
the ``pytest.set_trace()`` wrapper or explicitly disable pytest's output
capturing via ``py.test -s``.
.. _durations:
Profiling test execution duration
-------------------------------------
.. versionadded: 2.2
To get a list of the slowest 10 test durations::
py.test --durations=10
Creating JUnitXML format files
----------------------------------------------------
To create result files which can be read by Hudson_ or other Continuous
integration servers, use this invocation::
py.test --junitxml=path
to create an XML file at ``path``.
Creating resultlog format files
----------------------------------------------------
To create plain-text machine-readable result files you can issue::
py.test --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**::
py.test --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**::
py.test --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 py.test like this::
py.test -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 "py.test" 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'])
or pass in a string::
pytest.main("-x mytestdir")
You can specify additional plugins to ``pytest.main``::
# 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::
$ python myinvoke.py
*** test run reporting finishing
.. include:: links.inc