First make sure you have pip installed.
It is recommended that virtualenv and virtualenvwrapper be used in conjunction with firefox-ui-tests. Start by installing these.
Then:
pip install firefox-ui-tests
Alternatively you may want to clone the repo for development:
git clone https://github.com/mozilla/firefox-ui-tests.git
python setup.py develop
To run all tests:
firefox-ui-tests --binary <path to firefox binary>
To run a specific test or directory of tests:
firefox-ui-tests --binary <path to firefox binary> <path to test or directory>
For more options run:
firefox-ui-tests --help
Documentation for the puppeteer libraries are hosted on readthedocs.