How to invoke pytest¶
In general, pytest is invoked with the command pytest
(see below for other ways to invoke pytest). This will execute all tests in all files whose names follow the form test_*.py
or \*_test.py
in the current directory and its subdirectories. More generally, pytest follows standard test discovery rules.
Specifying which tests to run¶
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 (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
.
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 marks.
Run tests from packages
pytest --pyargs pkg.testing
This will import pkg.testing
and use its filesystem location to find and run tests from.
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
Profiling test execution duration¶
Changed in version 6.0.
To get a list of the slowest 10 test durations over 1.0s long:
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.
Managing loading of plugins¶
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 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:
pytest -p no:doctest
Other ways of calling pytest¶
Calling pytest through python -m pytest
¶
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
.
Calling pytest from Python code¶
You can invoke pytest
from Python code directly:
retcode = pytest.main()
this acts as if you would call “pytest” from the command line.
It will not raise SystemExit
but return the exit code instead.
You can pass in options and arguments:
retcode = pytest.main(["-x", "mytestdir"])
You can specify additional plugins to pytest.main
:
# content of myinvoke.py
import sys
import pytest
class MyPlugin:
def pytest_sessionfinish(self):
print("*** test run reporting finishing")
if __name__ == "__main__":
sys.exit(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
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.