Upgrading Rails 4 Controller Tests to Rails 5

At AppFolio, we're finally in the process of upgrading many of our Rails applications from Rails 4.2, up to Rails 5.2. Our first, and biggest step is to upgrade to Rails 5.0. While there are many parts necessary to complete this upgrade, I would like to share a few things we have done specifically to address the backwards incompatibility Rails 5 introduced in controller tests.