And you can even test your FirefoxOS apps with the Selenium WebDriver API!

Mozilla's talk about testing FirefoxOS, at the Google Test Automation Conference last week: http://www.youtube.com/watch?v=X41eqcmC2Dk

Writeup: http://lwn.net/SubscriberLink/548910/9c5d6bd1bd69f34c/

Demo of automated UI test using Appium to test an app on the FirefoxOS simulator: http://www.youtube.com/watch?v=1J0aXDbjiUE#t=34m30s