Ensuring py.test includes the application directory in sys.path

The easy way of doing it is, in terminal/cmd change directory to where the parent directory is, (e.g. in this case cd C:/.../my_project).

Then run: python -m pytest --cov=mypkg tests

No need to mess with the PYTHONPATH environment variable. By running with python -m pytest, it automatically adds the current directory to sys.path.

As you say yourself py.test basically assumes you have the PYTHONPATH setup up correctly. There are several ways of achieving this:

• Give your project a setup.py and use pip install -e . in a virtualenv for this project. This is probably the standard method.

• As a variation on this if you have a virtualenv but no setup.py use your venv's facility to add the projects directory on sys.path, e.g. pew add . if you use pew, or add2virtualenv . if you use virtualenv and the extensions of virtualenvwrapper.

• If you always like the current working directory on sys.path you can simply always export PYTHONPATH='' in your shell. That is ensure the empty string on on sys.path which python will interpret as the current working direcotry. This is potentially a security hazard though.

• My own favourite hack, abuse how py.test loads conftest files: put an empty conftest.py in the project's top-level directory.

The reason for py.test to behave this way is to make it easy to run the tests in a tests/ directory of a checkout against an installed package. If it would unconditionally add the project directory to the PYTHONPATH then this would not be possible anymore.