lxsameer: Use Sinatra or something similar in your test suite to run an api that simulates the communication necessary to your angularjs app. . . That is if you don't run a full rails app against your rails app that's running angularjs on top of it.
lxsameer: A piece of advice that you didn't ask for: consider making the front-end an entirely separate app (separate from your rails backend). It's not essential that it be done this way, I just personally find it easier.