Unit testing is a required part of a healthy software development lifecycle and a balanced breakfast. But test-driven development is a rockin' part of an *awesome* development lifecycle. What's the difference? If you don't test-drive the dev of your MarkLogic XQuery, you may never come back to test again. Test-driven XQuery development will ease your headaches, put you into the plush seat of a developer with confidence, and rocket you down the road to making all your wildest dreams come true. Kachow!