Once you start to get good at Test-Driven Development (TDD), you begin to learn the nuances of the discipline such as the fact that tests and code grow in very opposite directions. As the tests get more specific, the code gets more generic.
You also begin to learn that in the red/green/refactor cycle there are just a few standard gestures that move a test from red to green. This presentation discusses those gestures, called transformations and presents the idea that they when applied in a particular order and priority they can have a profound effect on the resulting code. This one is at the bleeding edge of TDD research; and will leave you with something to ponder.
Video producer: http://www.ndcoslo.com/