Test-Driven Development

TDD is the fundamental practice. Every line of production code must be written in response to a failing test.

For how to write good tests, load the testing skill. This skill focuses on the TDD workflow/process.

RED-GREEN-MUTATE-KILL MUTANTS-REFACTOR Cycle

RED: Write Failing Test First

• NO production code until you have a failing test
• Test describes desired behavior, not implementation
• Test should fail for the right reason

GREEN: Minimum Code to Pass

• Write ONLY enough code to make the test pass
• Resist adding functionality not demanded by a test