Test-Driven Development

A discipline for growing software guided by tests, one small step at a time.

When to Activate

Use this skill when:

• Writing code test-first for a new feature or module
• Starting a greenfield project and need a walking skeleton
• Applying outside-in development from acceptance tests to unit tests
• Sequencing tests to drive incremental design
• Creating a test list to plan implementation
• Reviewing whether tests are giving good design feedback
• Deciding between Fake It, Obvious Implementation, or Triangulation

The TDD Cycle

Five Steps