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.