After reading an article on it in TPJ and trying it out, I strongly recommend checking out Devel::Cover. It automates the process of seeing how much of your code is actually tested by your test suite and produces a fantastic HTML drill-down report. It will track the execution of statements, branches, conditions, subroutines, and pod.
Perhaps one day this will even lead to test-driven test development for those of us who are too lazy to do test-driven development itself -- i.e. what's the minimal amount of test suite I need to write to actually exercise the code I've already written?
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