At Appaloosa, most of our tests are written with Rspec, but we still have a certain amount of legacy Test Unit tests. Our Rspec and Test-Unit suites take up to 10 minutes each, so a full test suite runs in around 20 minutes. That’s a lot. We recently decided to invest time on improving our tests to gain time when developing. https://medium.com/appaloosa-store-engineering/tips-to-improve-speed-of-your-test-suite-8418b485205c