Add controller test helpers

Fair point.

We added it because in many tests there are only one record, or we only care about one record, and using .first or [0] everywhere felt a little redundant and noisy. Adding that method just shortened lines and made the tests read a little nicer.

I can see how it might not be immediately clear whats going on though. I think I still like it, but I'm biased and really could go either way. Do you want me to take it out or leave it in?