If I might make a suggestion, I'd recommend doing some kind of tracing when you run the tests so you can have a mapping of what parts of your code are exercised by which gems/tests. Then when you make changes to your code you can run the tests that relate to that part of the system first, thus giving you more confidence that your change didn't cause a regression. This should be much more efficient than simply doing a full gem run (although I'd recommend that too, since it could uncover hidden dependencies).