If you are used to other xUnit testing frameworks (e.g. JUnit) then you will find that Test::Unit is a pretty good port of those frameworks into Perl. The downside, however, is that is doesn't play well with the rest of the Perl testing framework. If you want to make use of the many useful testing modules on CPAN then Test::Class is the way to go.

And I strongly recommend that you get a copy of Perl Testing: A Developer's Notebook.