TestDrivenDevelopment

Test Driven Development is a programming methodology that focusses on
writing tests first to make sure everyone understand what you're all trying to
accomplish, and then writing the code to accomplish it. It generally involves
writing code text, along with the expected output.

If the tests pass, you've succeeded. Otherwise, you have to go back and re-
write your code until they do. In [eXtreme Programming], this is sufficient
and you can go on to the next task. You don't ask whether it's doing it
"right", because you supposedly did all that work when you designed your
tests.