Sorry, I never actually answered your question. I personally would likely test the modules but have an endpoint test that also proved everything works all the way through (happy path) and at least one error case. A login endpoint is pretty straight forward but most of the endpoints I’ve ever written have plenty of branching possibilities below the hood. So, instead of writing outside tests to hit every one of those branches, I isolate that code using whatever is the correct tool and exercise the branching logic. Then, the endpoint test would be to make sure that all of the pieces connect.
As far as which tests I start with, it 100% depends on the scenario every time. Sometimes I start really low-level and sometimes I start on the endpoint. The only thing that I’m dogmatic about is that I write my tests first.
