> That file is going to be a plain old Ruby class: not a Rails model, controller, etc. Isolating those would lead to pain, as anyone who's tried to do it knows.

> That file is going to be a plain old Ruby class: not a Rails model, controller, etc. Isolating those would lead to pain, as anyone who's tried to do it knows. I keep models very simple and allow them to integrate with the database; I keep controllers very simple and generally don't unit test them at all, although I do integration test them. This is what I was thinking of when I read DHH's post. Mock objects and indirection and all that certainly add complexity, but if your "business logic" is all in pure functions, or at least self-contained source files that don't do IO (and don't use "frameworks"), you don't need mocks to test it. Better to keep your glue code simple and do integration tests, while unit testing your actual logic, than to shoehorn extra indirection for mocking into complicated glue code. I gather that DHH complained because he had been doing the latter, and found that it sucked.