When your Tests Become so big they go OO Test::Class - allows you to subclass your tests good for testing subclassed objects Create two parallel class hierarchies: application and tests for each Class in your program make a test class. overkill for small test suites and non-OO programs don't use unless you find yourself repeating your test code over and over to compensate for classes in your program integrates with Test::Harness, Test::More, etc. prerequisites: Perl 5.6.1, Storable