====== Test Driven Development ======
\cite[S. ix]{Beck2003} In TDD, we
  * write new code only if an automated test has failed
  * eliminate duplication.

The TDD mantra \cite[S. x]{Beck2003}
  - red: write a little test that doesn't work, and perhaps doesn't even compile at first.
  - green: make the test work quickly, committing whatever sins necessary in the process.
  - refactor: eliminate all of the duplication created in merely getting the test to work.

The rhythm of TDD \cite[S. 1]{Beck2003}
  - quickly add a test
  - run all tests and see the new one fail
  - make a little change
  - run all tests and see them all succeed
  - refactor to remove duplication