Test::Harness can't analyze extra diagnostic information or run my INTERCAL/Befunge/Malbolge/Java program directly! You suck!
Frequently Unasked Question:
But Schwern, if we run all of our tests through Test::Harness, not only will it not report that extra diagnostic information but it doesn't run non-Perl tests very easily! Therefore we can't use TAP!
Frequently Unanswered Answer:
You can *run* the tests and *analyze* the results in separate steps. That's why they're separate steps.
I think people get hung up on the idea that there is or has to be only one way to run-and-analyze tests in one step.
TAP::Parser provides a more flexible alternative to Test::Harness.