TDD (Test-Driven Development) Skill

What it does

This skill embeds a disciplined Test-Driven Development workflow into agent work: identify the smallest observable behavior change, write a failing test, make the minimal production change to pass, then refactor while keeping tests green. It forces incremental, verifiable progress so agents avoid speculative or broad changes without test coverage.

When to use it

Use this skill when implementing new features, fixing reproducible bugs, adding regression coverage, or changing public business logic where tests can verify behavior. Do NOT use for documentation-only edits, purely mechanical renames, or when no test harness exists.

What's included

• Scripts: none (has_scripts=false)
• References: none (has_references=false)
• Instructions: clear operating rules and a four-step workflow (Understand → Red → Green → Refactor) with heuristics for test selection and command strategy. Includes an output template for status updates and rules for communication.

Compatible agents

Best suited to coding-capable agents that can run project tests and edit code (Copilot-style agents, Codex, GitHub Copilot Chat, or similar). The skill assumes access to the repository's test tooling and the ability to run test commands and edit files.