How do I add tests to an existing Rails project?

If you have little testing experience, I would suggest getting some practice on a fresh Rails app before trying to introduce testing to the existing Rails project you want to add tests to.Adding tests to an existing project is a distinct skill from writing tests for new projects. Adding tests to an existing project can be difficult even for very experienced testers, for reasons described below.At the same time, you probably don’t want to wait a year to learn testing before you start enjoying the benefits of testing on your existing Rails app. What I would suggest is to first start a fresh throwaway Rails app for the purpose of learning testing. Then, once you’ve gotten a little experience there, see if you can apply something to your existing Rails app. Then, if things get too hard in the existing app, switch back to the throwaway app so you can strengthen your skills more. Continue switching back and forth until you don’t need to anymore.