TDD Best Practices

Test-Driven Development with behavior-focused testing, factory patterns, and the Red-Green-Refactor cycle.

Core Principle

Every line of new or changed behavior must be written in response to a failing test.

This is non-negotiable. If you're typing production code that adds or changes behavior without a failing test demanding it, you're not doing TDD. Refactoring is the one exception: it changes structure while every test stays green, so it demands no new failing test.

Only a test run is evidence. A compiling build, a rendering page, a type check, or a manual inspection does not prove behavior. Code that exists without a test run behind it is ad-hoc coding, not TDD, however well it works. At every transition, report what you ran, what the result was, and why it counts.

The Sacred Cycle: Red → Green → Refactor