| name | tdd-pro |
| description | Test-driven development workflow using red-green-refactor for features, bug fixes, and risky behavior changes. Adapted from Matt Pocock-style TDD for Codex v4.1. Use when tests can clarify requirements, prevent regressions, or guide implementation in small vertical slices. |
TDD Pro
Workflow
- Identify one externally visible behavior.
- Write the smallest failing test that proves the missing behavior or bug.
- Run the narrow test and confirm it fails for the expected reason.
- Implement the smallest code change to pass.
- Run the test and relevant adjacent checks.
- Refactor only after green.
- Repeat for the next behavior or edge case.
Good Tests
- Assert behavior, not private implementation.
- Use realistic inputs and domain language.
- Cover one reason to fail per test where practical.
- Include regression tests for fixed bugs.
- Keep mocks at external boundaries.
- Avoid snapshot-only tests for meaningful logic.
When Not To Force TDD
- Pure styling changes with low behavioral risk.
- Exploratory prototypes intended to be thrown away.
- Codebases with no viable test harness, unless adding one is in scope.
Output
Report failing test added, implementation change, final test command, and result. If TDD was skipped, state why.
