You may want to add something about creating a copy of the profile, such as:

> If a profile is specified when running the tests (recommended), a clone of to profile will be used. This helps to ensure that all tests run in a clean state, however if you also intend to launch and interact with the desktop build manually I would recommend making a copy of the default profile and using the copy for your tests.

See http://blargon7.com/2013/07/running-firefox-os-ui-tests-without-a-device-revised/