A short while back I wondered about something like Test::Unit. Well, it exists for Perl, but it looks like it's somewhat defunct (the owner put out a call for someone else to take it over back in November). Also, I wasn't "getting it". Finally someone, somewhere mentioned that Test::Class was picking up the slack.
If you've got a pure OO module, I think this is the module you'll want to use. It has already proved to be very convenient in the 5 minutes I've been using it for the new test suite I'm planning for Set::Array.
The only thing I need to figure out now is how to setup a nice test runner.