Only run tests in 'tests' directory.
Only run tests in 'tests' directory.

Having e.g. Cython installed in a virtualenv inside the project root make pytest also find the Cython test cases. These take a lot of time and also fail without some additional libraries being installed.
anthrotype/pyclipper,greginvm/pyclipper,greginvm/pyclipper,greginvm/pyclipper,anthrotype/pyclipper,anthrotype/pyclipper