Non-idiomatic rspec tests

[MatMoore]

From: https://trello.com/c/vWVU6a1i/25-rummager-test-suite

We're now using rspec instead of minitest, but there are some things we need to change in order to make them idiomatic. Maybe we should run something like https://github.com/backus/rubocop-rspec over the tests.