Command line options and configuration file settings

You can get help on command line options and values in INI-style configurations files by using the general help option:

pytest -h   # prints options _and_ config file settings

This will display command line and configuration file settings which were registered by installed plugins.

Initialization: determining rootdir and inifile

pytest determines a rootdir for each test run which depends on the command line arguments (specified test files, paths) and on the existence of ini-files. The determined rootdir and ini-file are printed as part of the pytest header during startup.

Here’s a summary what pytest uses rootdir for:

  • Construct nodeids during collection; each test is assigned a unique nodeid which is rooted at the rootdir and takes in account full path, class name, function name and parametrization (if any).
  • Is used by plugins as a stable location to store project/test run specific information; for example, the internal cache plugin creates a .pytest_cache subdirectory in rootdir to store its cross-test run state.

Important to emphasize that rootdir is NOT used to modify sys.path/PYTHONPATH or influence how modules are imported. See pytest import mechanisms and sys.path/PYTHONPATH for more details.

--rootdir=path command-line option can be used to force a specific directory. The directory passed may contain environment variables when it is used in conjunction with addopts in a pytest.ini file.

Finding the rootdir

Here is the algorithm which finds the rootdir from args:

  • determine the common ancestor directory for the specified args that are recognised as paths that exist in the file system. If no such paths are found, the common ancestor directory is set to the current working directory.
  • look for pytest.ini, tox.ini and setup.cfg files in the ancestor directory and upwards. If one is matched, it becomes the ini-file and its directory becomes the rootdir.
  • if no ini-file was found, look for upwards from the common ancestor directory to determine the rootdir.
  • if no was found, look for pytest.ini, tox.ini and setup.cfg in each of the specified args and upwards. If one is matched, it becomes the ini-file and its directory becomes the rootdir.
  • if no ini-file was found, use the already determined common ancestor as root directory. This allows the use of pytest in structures that are not part of a package and don’t have any particular ini-file configuration.

If no args are given, pytest collects test below the current working directory and also starts determining the rootdir from there.

warning:custom pytest plugin commandline arguments may include a path, as in pytest --log-output ../../test.log args. Then args is mandatory, otherwise pytest uses the folder of test.log for rootdir determination (see also issue 1435). A dot . for referencing to the current working directory is also possible.

Note that an existing pytest.ini file will always be considered a match, whereas tox.ini and setup.cfg will only match if they contain a [pytest] or [tool:pytest] section, respectively. Options from multiple ini-files candidates are never merged - the first one wins (pytest.ini always wins, even if it does not contain a [pytest] section).

The config object will subsequently carry these attributes:

  • config.rootdir: the determined root directory, guaranteed to exist.
  • config.inifile: the determined ini-file, may be None.

The rootdir is used as a reference directory for constructing test addresses (“nodeids”) and can be used also by plugins for storing per-testrun information.


pytest path/to/testdir path/other/

will determine the common ancestor as path and then check for ini-files as follows:

# first look for pytest.ini files
path/setup.cfg  # must also contain [tool:pytest] section to match
path/tox.ini    # must also contain [pytest] section to match
... # all the way down to the root

# now look for
... # all the way down to the root

How to change command line options defaults

It can be tedious to type the same series of command line options every time you use pytest. For example, if you always want to see detailed info on skipped and xfailed tests, as well as have terser “dot” progress output, you can write it into a configuration file:

# content of pytest.ini or tox.ini
# setup.cfg files should use [tool:pytest] section instead
addopts = -ra -q

Alternatively, you can set a PYTEST_ADDOPTS environment variable to add command line options while the environment is in use:

export PYTEST_ADDOPTS="-v"

Here’s how the command-line is built in the presence of addopts or the environment variable:

<pytest.ini:addopts> $PYTEST_ADDOPTS <extra command-line arguments>

So if the user executes in the command-line:

pytest -m slow

The actual command line executed is:

pytest -ra -q -v -m slow

Note that as usual for other command-line applications, in case of conflicting options the last one wins, so the example above will show verbose output because -v overwrites -q.

Builtin configuration file options

For the full list of options consult the reference documentation.