Traits are an easy way to share code between classes, but how do you test them? I used to test the trait in isolation and not test the traits functionality while testing the classes that used the trait. This lead to passing tests and bugs. I tried copy and pasting code between tests, but this always seemed like a bad solution. Lately, I've been using traits to test traits and have been happy with the results so far.

While preparing for a talk, I realized that I'd been writing unit tests wrong for the last 3 years. I'd always approached test writing iteratively rather than from the outside in. With this one change, I was able to write cleaner more maintainable tests.