We stop Autotest and then perform the upgrade (or upgrades). For example, see:
- Upgrading to Heckle 1.4.0 on Mac OS X Tiger
- Upgrading to RSpec 1.0.0 on Mac OS X Tiger
- Upgrading to Spec::UI 0.2.2 on Mac OS X Tiger
Finally, we resume Autotest and everything should just keep working.