TDD Skill

When to use this skill

• new features that can be unit tested
• bug fixes (always add a regression test if practical)
• refactors (protect behavior with tests first)

Rules

• Prefer red -> green -> refactor.
• If tests are hard, still add verification: minimal repro script, integration test, or clear manual steps.
• Keep tests focused: one behavior per test where possible.
• Name tests by behavior, not implementation details.

Process

1. Define the behavior change (what should be true after).
2. Write/adjust a test to capture it (make it fail first if possible).
3. Implement the minimal change to pass.
4. Refactor if needed (keep passing).
5. Run the relevant test suite + any linters.

Output requirements

When you change code, include:

• what tests you added/changed
• how to run them
• what they prove