Test-Driven Development

Tests verify behavior through public interfaces, not implementation details. See principles.md for testing philosophy and mocking guidelines.

DO NOT write all tests first, then all implementation. Each cycle: one test → minimal code to pass → next test. See examples.md for demonstrations.

Workflow

1. Planning

• Ask user: "What should the public interface look like? Which behaviors are most important to test?"
• Identify opportunities for deep modules (small interface, deep implementation)
• Design interfaces for testability
• List behaviors to test (prioritize critical paths — you can't test everything)
• Get user approval before writing code

2. Tracer Bullet