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

• Define the behavior change (what should be true after).

• Write/adjust a test to capture it (make it fail first if possible).

• Implement the minimal change to pass.

• Refactor if needed (keep passing).

• 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