Change summary
Currently, if you run roca and it doesn't find any test files, we exit with code 0 and pretend everything is fine. If you do the same thing with a framework like jest, though, it exits with code 1 and displays an error. We should let the user know when no tests are found.

Change summary
Currently, if you run
rocaand it doesn't find any test files, we exit with code 0 and pretend everything is fine. If you do the same thing with a framework likejest, though, it exits with code 1 and displays an error. We should let the user know when no tests are found.