tdd-practices

Test-driven development (TDD) is a discipline where you write tests before implementation code. The RED-GREEN-REFACTOR cycle guides you: write a failing test (RED), implement minimal code to pass it (GREEN), then improve the code without changing behavior (REFACTOR). This approach ensures every feature has verifiable tests and reduces bugs.

RED-GREEN-REFACTOR is a three-phase TDD workflow. RED: write a test that fails. GREEN: write minimal code to pass the test. REFACTOR: improve code quality, design, and documentation while keeping tests passing. This cycle repeats for each feature, ensuring test coverage and preventing feature drift.

AI Red Flags catch loops, test ticking (writing tests without real implementation), and unauthorized feature drift during development. The structured phase-based workflow enforces test isolation, prevents scope creep, and maintains regression safety through continuous testing and explicit verification at each step.

TDD applies across feature development, bug fixes, and refactoring. For each task, follow the same RED-GREEN-REFACTOR cycle: write a test that reproduces the issue or validates the improvement, implement the fix or refactoring, then verify with passing tests and documentation updates.

Begin by creating a test list outlining the small, verifiable tests required for your task. Run a baseline to establish current behavior. Then initiate a TDD session following the five-phase workflow, incorporating AI feedback and adhering to test isolation rules to maintain code integrity.

TDD enforces one small, verifiable test per step with explicit test isolation, preventing hidden dependencies. Continuous regression testing through each phase catches breakage immediately. Regular refactoring and documentation updates during the REFACTOR phase maintain code clarity and long-term safety.