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Testing First

Category: Engineering  ·  Sub-category: testing  ·  Last updated:
type:review
Enforces test-first implementation — the Iron Law (no production code without a failing test first), RED-GREEN-REFACTOR with both verification beats mandatory, and the rationalization table that catches "just this once". Cycle evidence lands in the lane's PROGRESS.md, and completion hands off to work-verify instead of being self-claimed. Use before writing implementation code for any feature, bugfix, or behavior change; when writing or reviewing a test; when tests are being added after the fact; when authoring a skill or an eval, where the eval is the failing test; and whenever time pressure, sunk cost, or "I already manually tested it" is arguing for skipping TDD. Covers test-driven development (TDD).
Security AStatic scan found no risk patternsHow grading works ›

From the source SKILL.md

<!-- Derived from superpowers' test-driven-development/SKILL.md (v6.3.0), MIT License, Copyright (c) 2025 Jesse Vincent. Adapted 2026-08-19. Classified substantial (MAT-94); evidence: work/mat-94-attribution-skills/DECISIONS.md. Full upstream permission notice: NOTICE (repo root). -->

What this skill does

Testing First is a community-contributed Claude Code skill in the testing sub-category. It ships as a SKILL.md file that Claude Code auto-discovers under ~/.claude/skills/testing-first/ and loads when your prompt matches the skill's trigger.

Who uses this skill

The Testing First Claude Code skill is built for software engineers, backend developers, full-stack teams, and technical leads building and maintaining production systems. It's part of ClaudSkills (also referred to as Claude Skills or Claude Code Skills) — the open community-curated registry of 188,000+ SKILL.md files for Anthropic's Claude Code agent and the wider Claude ecosystem (Claude API, Claude Agent SDK).

How to install

Free

Manual install (2 steps)

mkdir -p ~/.claude/skills/testing-first
curl -L https://claudskills.com/skills/testing-first/SKILL.md \
  -o ~/.claude/skills/testing-first/SKILL.md

Or just download SKILL.md directly and drop it into ~/.claude/skills/testing-first/. Claude Code auto-discovers it on next session.

Skills live at ~/.claude/skills/testing-first/SKILL.md on macOS/Linux, or %USERPROFILE%\.claude\skills\testing-first\SKILL.md on Windows. See the full install guide for step-by-step instructions.

Telegram

📱 Install from your phone or desktop Telegram

Open @claudskills_bot on Telegram, tap Open Desktop App, and the desktop app installs this skill for you. Or share the bot link with a colleague — they get the same one-tap install. Learn more →

Pro

One-click install via the desktop app

The ClaudSkills desktop app installs any skill directly into ~/.claude/skills/ with one click — no terminal required. Pro starts at $9/mo or $149 lifetime.

Pro

For the full experience including quality scoring and one-click install features for each skill — upgrade to Pro.

See pricing → Download desktop app

Frequently asked questions

How do I install the Testing First Claude Code skill?
Install via the ClaudSkills desktop app (one click) or copy SKILL.md from the source repository to ~/.claude/skills/testing-first/SKILL.md and restart Claude Code. Both flows are detailed at claudskills.com/install/.
What does the Testing First skill do?
Enforces test-first implementation — the Iron Law (no production code without a failing test first), RED-GREEN-REFACTOR with both verification beats mandatory, and the rationalization table that catches "just this once". Cycle evidence lands in the lane's PROGRESS.md, and completion hands off to work-verify instead of being self-claimed. Use before writing implementation code for any feature, bugfix, or behavior change; when writing or reviewing a test; when tests are being added after the fact; when authoring a skill or an eval, where the eval is the failing test; and whenever time pressure, sunk cost, or "I already manually tested it" is arguing for skipping TDD. Covers test-driven development (TDD).
Is this skill free to install?
Yes. ClaudSkills is an open registry — every skill keeps its source repository's license, and manual install via copy is free. ClaudSkills Pro ($9/mo, $79/yr, or $149 one-time) adds one-click install via the desktop app and a multi-signal Quality Score.
When should I use the Testing First skill?
Use Testing First when your Claude Code task falls under the Engineering category — specifically in the testing area. Claude Code auto-discovers installed skills and invokes the right one based on the task description, so you can also ask Claude directly (e.g. "use Testing First" or describe the task and let Claude pick). Browse related skills at /category/engineering/.
What is a Claude Code skill and how does the Testing First skill fit in?
A Claude Code skill is a SKILL.md file that lives under ~/.claude/skills/<name>/ and tells the Claude Code CLI agent how to perform a specific task (instructions, prompts, allowed tools). Skills are auto-discovered at session start. Testing First is one of 67,000+ skills indexed in the open ClaudSkills catalog, classified under the Engineering category. Learn more at /learn/what-is-a-claude-skill/.

Attribution & license

Cite this skill

If you reference this skill in a blog post, paper, or documentation, you can cite it as:

APA
bygama. (2026). Testing First [Claude Code skill]. ClaudSkills. https://claudskills.com/skills/testing-first/
BibTeX
@misc{testing-first-2026,
  author    = {bygama},
  title     = {Testing First [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/testing-first/}
}

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Grade A · scanned 2026-08-20 — free static scan against the OWASP Agentic Skills Top 10.

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More Engineering skills

Browse all Engineering skills in the ClaudSkills registry, or explore these other picks from the same category:

Browse all Engineering skills → Top 100 skills
Part of ClaudSkills — the open registry for Claude Skills & Claude Code Skills.  ·  What's New  ·  Install guide  ·  About  ·  llms.txt

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