Ultimate TDD

Build features test-first through disciplined RED-GREEN-REFACTOR cycles. Each cycle adds one small behavior, keeping the codebase working at every step.

Operating Rules

1. Always run tests — never assume they pass. Execute the test command and read the output.
2. One test at a time — never write multiple tests before seeing them fail.
3. Minimal production code — write only what the current failing test demands. Nothing more.
4. Respect existing structure — before creating test files, find where tests already live. If a test file exists for the module you're working on, add to it.
5. No automatic commits — the user decides when to commit.
6. Phase names stay out of git — RED, GREEN, REFACTOR are useful conversation terms, but commit messages should describe actual changes (e.g. "add email validation", not "RED: write failing test for email").
7. Not for retroactive testing — this skill is for building new functionality test-first. Adding tests to existing untested code is a different activity.

Phase 0: Project Reconnaissance

Before writing any test, understand the project's testing setup. This runs once at the start.

1. Detect the test framework and runner. Check config files (package.json, pyproject.toml, go.mod, Cargo.toml, Gemfile, etc.) and look for runner configs (jest.config.*, vitest.config.*, pytest.ini, .rspec). See references/framework-detection.md for the full detection guide.