So, it seems like you've finished writing your awesome gem. However, are you sure that your gem is working perfectly against multiple versions of its dependency? Are you sure that you didn't break any backward compatibility? In this talk, I'm going to show you the approach we have been taken to test our gems against multiple versions of dependencies, such as testing against Rails 3.2 and Rails 3.1. I'm also going to introduce you to our gem called "Appraisal" which helps you generating Gemfiles to be used with Bundler, and also guide it to running your test suite against those multiple Gemfiles. Lastly, I'm going to show you how you can config Travis CI to test your gem against those multiple versions of dependencies.