When writing my integration tests I learnt how hard global variables are to work with. By decoupling global variables from your services you can test systems completely aside from the global variables they will interact with in practice. I learnt what middleware is. Services that process and filter requests and can be stacked on top of each other so responses can be returned early should requirements not be met. For example when running through my middleware a response will be returned early should it fail auth checks. This provides a convenient structure to test, as each middleware can be treated as modular. It also allows for further services to be easily added to the stack. In implementing Bitbucket pipeline into my project (to run my unit test on PRs) I got to learn a bit more about how a developers workflow looks like at ChurchSuite.