Rails freelancer here.<p>The first thing that surprises me is that the author talks about &#x27;wasting&#x27; time, which is &#x27;his precious resource&#x27;.<p>How is that? The more you work, the more you bill, if you got any decent deal with your client.<p>I&#x27;ve maintained many existing Rails projects. Personally the FIRST thing I do when joining a project is adding&#x2F;improving the test suite. Often the owner will hesitate, but selling the merits of a technical decision should be part of your freelancer skillset.<p>Just like the author, I give a special importance to Capybara tests, for the simple reason that they implicitly hit the full stack.<p>However, I test anything else that can be reasonably tested. Controller tests are important for testing APIs, authorization, and more. Personally I like to set `render_views` so controllers specs implicitly assert that the views can be rendered.<p>If your app has any real business logic in it, you&#x27;ll want to test models as well.<p>Do your mails render, and your jobs run? Only tests can tell (in the long term).<p>Well-written, non-redundant tests are priceless for your own sanity, and also for the health&#x2F;viability of the project. Someone WILL maintain your project after your freelancer deal is over.<p>ps - I don&#x27;t TDD.