To test python-OBD, you will need to pip install pytest and install the module (preferably in a virtualenv) by running python setup.py install. The end-to-end tests will also require obdsim to be running in the background. When starting obdsim, note the "SimPort name" that it creates, and pass it as an argument to py.test.
To run all tests, run the following command:
$ py.test --port=/dev/pts/<num>
For more information on pytest with virtualenvs, read more here