Test-Driven Development Rules

from Kent Beck. Test-Driven Development by Example.

1. Test-Driven Development Simple Rules:

• Write new code only if an auomated test has failed
• Eliminate duplication

2. TDD Generating Rules:

• We must design organically, with running code providing feedback between decisions.
• We must write our own tests, because we can't wait 20 times per day for someone else to write a test.
• Our development environment must provide rapid reponse to small changes.
• Our designs must consist of many highly cohesive, loosely coupled components, just to make testing easy.

3. The Order of Programming:

• Red---Write a little test that doesn't work, and perhaps dosn'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.

Red/green/refactor---the TDD mantra.