Agent skill

Red Green Refactor

Guides the red-green-refactor TDD workflow: write a failing test first, implement the minimum code to make it pass, then refactor while keeping tests green.

Apache-2.0Auto-check passedTesting & QA

Install Red Green Refactor

skills CLI

$ npx skills add rohitg00/skillkit --skill red-green-refactor -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install rohitg00/skillkit red-green-refactor --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/rohitg00/skillkit.git skills-src && mkdir -p .claude/skills && cp -r skills-src/packages/core/src/methodology/packs/testing/red-green-refactor .claude/skills/red-green-refactor && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "red-green-refactor" agent skill from https://github.com/rohitg00/skillkit/tree/main/packages/core/src/methodology/packs/testing/red-green-refactor into .claude/skills/red-green-refactor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "red-green-refactor", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/rohitg00/skillkit/tree/main/packages/core/src/methodology/packs/testing/red-green-refactor

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add rohitg00/skillkit --skill red-green-refactor -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install rohitg00/skillkit red-green-refactor --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/rohitg00/skillkit.git skills-src && mkdir -p .agents/skills && cp -r skills-src/packages/core/src/methodology/packs/testing/red-green-refactor .agents/skills/red-green-refactor && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "red-green-refactor" agent skill from https://github.com/rohitg00/skillkit/tree/main/packages/core/src/methodology/packs/testing/red-green-refactor into .agents/skills/red-green-refactor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "red-green-refactor", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add rohitg00/skillkit --skill red-green-refactor -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install rohitg00/skillkit red-green-refactor --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/rohitg00/skillkit.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/packages/core/src/methodology/packs/testing/red-green-refactor .cursor/skills/red-green-refactor && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "red-green-refactor" agent skill from https://github.com/rohitg00/skillkit/tree/main/packages/core/src/methodology/packs/testing/red-green-refactor into .cursor/skills/red-green-refactor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "red-green-refactor", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/rohitg00/skillkit.git --path packages/core/src/methodology/packs/testing/red-green-refactor

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add rohitg00/skillkit --skill red-green-refactor -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install rohitg00/skillkit red-green-refactor --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/rohitg00/skillkit.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/packages/core/src/methodology/packs/testing/red-green-refactor .gemini/skills/red-green-refactor && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "red-green-refactor" agent skill from https://github.com/rohitg00/skillkit/tree/main/packages/core/src/methodology/packs/testing/red-green-refactor into .gemini/skills/red-green-refactor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "red-green-refactor", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install rohitg00/skillkit red-green-refactor

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add rohitg00/skillkit --skill red-green-refactor -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/rohitg00/skillkit.git skills-src && mkdir -p .github/skills && cp -r skills-src/packages/core/src/methodology/packs/testing/red-green-refactor .github/skills/red-green-refactor && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "red-green-refactor" agent skill from https://github.com/rohitg00/skillkit/tree/main/packages/core/src/methodology/packs/testing/red-green-refactor into .github/skills/red-green-refactor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "red-green-refactor", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add rohitg00/skillkit --skill red-green-refactor -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install rohitg00/skillkit red-green-refactor --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/rohitg00/skillkit.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/packages/core/src/methodology/packs/testing/red-green-refactor .opencode/skills/red-green-refactor && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "red-green-refactor" agent skill from https://github.com/rohitg00/skillkit/tree/main/packages/core/src/methodology/packs/testing/red-green-refactor into .opencode/skills/red-green-refactor/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "red-green-refactor", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: red-green-refactor
GitHub stars: 1.5k
Token cost: ~1.3k tokens
SKILL.md length: 401 words
Files: 1
Skills in repo: 14
Repo updated: Jun 2, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

Guides the red-green-refactor TDD workflow: write a failing test first, implement the minimum code to make it pass, then refactor while keeping tests green.

Works in 3 steps: RED Phase — Write a Failing Test → GREEN Phase — Make the Test Pass → REFACTOR Phase — Improve the Code
A user asks to practice TDD
SKILL.md covers The Cycle, End-to-End Example: Adding a…, Workflow Steps and Decision Points, plus 3 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Red Green Refactor is an agent skill from rohitg00/skillkit. Guides the red-green-refactor TDD workflow: write a failing test first, implement the minimum code to make it pass, then refactor while keeping tests green. Use when a user asks to practice TDD, write tests first, follow red-green-refactor, do test-driven development, write failing tests before code, or phrases like 'make the test pass', 'test coverage', or 'unit tests before implementation'.

Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Testing & QA, covering Test-driven development. The repository describes itself as: Supercharge AI coding agents with portable skills. Install, translate & share skills across Claude Code, Cursor, Codex, Copilot & 40 more. The licence is Apache-2.0.

When your agent uses it

A user asks to practice TDD
Write tests first
Follow red-green-refactor
Do test-driven development

Example prompts

“make the test pass”
“test coverage”
“unit tests before implementation”
“/red-green-refactor”

Workflow steps

3 steps, taken from the step headings in SKILL.md.

RED Phase — Write a Failing Test
GREEN Phase — Make the Test Pass
REFACTOR Phase — Improve the Code

What it can do on your machine

Read from SKILL.md and the folder at commit d2e5c34. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
No scripts in the folder and no shell commands in SKILL.md (its code samples are javascript).
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Red Green Refactor loads about 1.3k tokens when it runs. Until then it costs about 104 tokens; SKILL.md has 401 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~104
When it runs · the whole SKILL.md, loaded when a task matches: ~1.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from rohitg00/skillkit at commit d2e5c34, republished under its Apache-2.0 licence (© rohitg00). 401 words, ~1,309 tokens.

Download SKILL.mdSave it as .claude/skills/red-green-refactor/SKILL.md (or your agent's skills folder).

name: red-green-refactor
description: Guides the red-green-refactor TDD workflow: write a failing test first, implement the minimum code to make it pass, then refactor while keeping tests green. Use when a user asks to practice TDD, write tests first, follow red-green-refactor, do test-driven development, write failing tests before code, or phrases like 'make the test pass', 'test coverage', or 'unit tests before implementation'.
version: 1.0.0
triggers: tdd, test driven, write tests first, red green refactor, failing test
tags: tdd, testing, quality, methodology
difficulty: intermediate
estimatedTime: 15
relatedSkills: testing/test-patterns, testing/anti-patterns

Red-Green-Refactor Methodology

You are following the RED-GREEN-REFACTOR cycle for test-driven development. Every new feature, bug fix, or behavior change starts with a failing test.

The Cycle

1. RED Phase — Write a Failing Test

Understand the requirement — what specific behavior must exist?
Write one test asserting that behavior
Run the test — it MUST fail (red)
Verify the failure reason — not a syntax error, but a missing implementation

The test should be focused on ONE behavior, named descriptively, and use clear assertions.

Executable example (Jest):

// calculateTotal.test.js
const { calculateTotal } = require('./calculateTotal');

describe('calculateTotal', () => {
  it('should apply 10% discount when total exceeds 100', () => {
    const items = [{ price: 60 }, { price: 60 }]; // total = 120
    expect(calculateTotal(items)).toBe(108); // 120 * 0.90
  });
});

Running this now produces: Cannot find module './calculateTotal' — correct RED state.

2. GREEN Phase — Make the Test Pass

Write the minimum code needed to pass the test. Don't add anything extra.

// calculateTotal.js
function calculateTotal(items) {
  const total = items.reduce((sum, item) => sum + item.price, 0);
  return total > 100 ? total * 0.9 : total;
}
module.exports = { calculateTotal };

Run the test — it passes. GREEN achieved. Stop here; resist adding more logic.

3. REFACTOR Phase — Improve the Code

With a passing test as your safety net, clean up the implementation. Run tests after every change.

// calculateTotal.js — refactored for clarity
const DISCOUNT_THRESHOLD = 100;
const DISCOUNT_RATE = 0.9;

function calculateTotal(items) {
  const subtotal = items.reduce((sum, { price }) => sum + price, 0);
  return subtotal > DISCOUNT_THRESHOLD ? subtotal * DISCOUNT_RATE : subtotal;
}
module.exports = { calculateTotal };

Test still passes — GREEN maintained. Constants now communicate intent.

End-to-End Example: Adding a New Behavior

Next requirement: apply a 15% discount when total exceeds 200.

RED — write the failing test first:

it('should apply 15% discount when total exceeds 200', () => {
  const items = [{ price: 110 }, { price: 110 }]; // total = 220
  expect(calculateTotal(items)).toBe(187); // 220 * 0.85
});

GREEN — extend the implementation minimally:

function calculateTotal(items) {
  const subtotal = items.reduce((sum, { price }) => sum + price, 0);
  if (subtotal > 200) return subtotal * 0.85;
  if (subtotal > 100) return subtotal * 0.9;
  return subtotal;
}

REFACTOR — remove duplication with a tiered structure:

const DISCOUNT_TIERS = [
  { threshold: 200, rate: 0.85 },
  { threshold: 100, rate: 0.9 },
];

function calculateTotal(items) {
  const subtotal = items.reduce((sum, { price }) => sum + price, 0);
  const tier = DISCOUNT_TIERS.find(({ threshold }) => subtotal > threshold);
  return tier ? subtotal * tier.rate : subtotal;
}

Both tests pass — ready for the next cycle.

Workflow Steps

Create or open the test file first
Write ONE failing test for the smallest testable unit
Implement minimally — just enough to pass
Refactor if needed — while tests stay green
Repeat for the next behavior

Show full SKILL.md (155 more words)Show less

Decision Points

Write a new test when:

Adding a new feature or behavior
Fixing a bug (test the bug first, then fix it)
Handling an edge case discovered during implementation

Don't write a test when:

Pure refactoring (existing tests already cover the behavior)
Non-functional changes (formatting, comments)
Third-party library internals

Verification Checklist

All new code has corresponding tests
Tests fail when the feature is removed
Tests pass consistently (not flaky)
Code has been refactored for clarity
No unnecessary code was added

Common Mistakes to Avoid

Writing tests after code — defeats the design benefit of TDD
Writing multiple tests at once — one test drives one change
Passing tests with hacks — the test should drive good design
Skipping the refactor phase — technical debt accumulates
Testing implementation details — test behavior, not internals

Integration with Other Skills

test-patterns: Patterns for structuring tests
anti-patterns: Common testing mistakes to avoid
debugging/root-cause-analysis: When tests reveal unexpected failures

Files

Just SKILL.md in packages/core/src/methodology/packs/testing/red-green-refactor of rohitg00/skillkit.

Open the folder on GitHubat commit d2e5c34

Compare with similar skills

Red Green Refactor next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Red Green Refactor compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Red Green Refactor this skillrohitg00/skillkit	1.5k	—	~1.3k	Automated safety check: Pass	Apache-2.0	4 mo ago
TDDpietheinstrengholt/rssmonster	564	30 repos	~906	Automated safety check: Pass	MIT	yesterday
TDD WorkflowhellangleZ/burn-in-cceverywhere-ralph	112	11 repos	~2.4k	Automated safety check: Pass	None	8 mo ago
TDDsanity-io/sanity	6.4k	20 repos	~1k	Automated safety check: Pass	MIT	today
Test Driven Developmentfarm-fe/farm	5.6k	51 repos	~2.5k	Automated safety check: Pass	MIT	18 days ago
Tapd Story PipelineTencentBlueKing/bk-bcs	840	—	~2.6k	Automated safety check: Pass	Custom licence	yesterday

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Questions about Red Green Refactor

What does Red Green Refactor do?

Guides the red-green-refactor TDD workflow: write a failing test first, implement the minimum code to make it pass, then refactor while keeping tests green. Red Green Refactor is an agent skill from rohitg00/skillkit. Guides the red-green-refactor TDD workflow: write a failing test first, implement the minimum code to make it pass, then refactor while keeping tests green.

When should I use Red Green Refactor?

Red Green Refactor fits situations like: A user asks to practice TDD; write tests first; follow red-green-refactor; do test-driven development.

How do I install Red Green Refactor in Claude Code?

Run `npx skills add rohitg00/skillkit --skill red-green-refactor -a claude-code`. Or copy the skill folder (packages/core/src/methodology/packs/testing/red-green-refactor in rohitg00/skillkit) into .claude/skills/red-green-refactor in your project. Claude Code loads it when a task matches its description.

How do I install Red Green Refactor in Codex?

Run `npx skills add rohitg00/skillkit --skill red-green-refactor -a codex`. Or copy the skill folder (packages/core/src/methodology/packs/testing/red-green-refactor in rohitg00/skillkit) into .agents/skills/red-green-refactor in your project. Codex loads it when a task matches its description.

Can I use Red Green Refactor in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add rohitg00/skillkit --skill red-green-refactor -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/red-green-refactor, .gemini/skills/red-green-refactor, .github/skills/red-green-refactor and .opencode/skills/red-green-refactor in your project.

What does Red Green Refactor need to run?

SKILL.md names no scripts, command-line tools or credentials: Red Green Refactor is instructions for the agent only.

Does Red Green Refactor access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Red Green Refactor safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Red Green Refactor use?

Red Green Refactor is published under the Apache-2.0 licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Red Green Refactor use?

About 1.3k tokens (SKILL.md is roughly 5.2k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Red Green Refactor?

Skills that share tags, products or a category with Red Green Refactor: TDD (pietheinstrengholt/rssmonster, 564 stars), TDD Workflow (hellangleZ/burn-in-cceverywhere-ralph, 112 stars), TDD (sanity-io/sanity, 6.4k stars) and Test Driven Development (farm-fe/farm, 5.6k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Red Green Refactor?

rohitg00 (a GitHub user) maintains it in rohitg00/skillkit, which has 1,546 GitHub stars. The repository holds 14 skills in this directory. The repository was last updated on June 2, 2026.

Source: rohitg00/skillkit on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Red Green Refactor

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Red-Green-Refactor Methodology

The Cycle

1. RED Phase — Write a Failing Test

2. GREEN Phase — Make the Test Pass

3. REFACTOR Phase — Improve the Code

End-to-End Example: Adding a New Behavior

Workflow Steps

Decision Points

Write a new test when:

Don't write a test when:

Verification Checklist

Common Mistakes to Avoid

Integration with Other Skills

Files

Compare with similar skills

Similar skills

More from rohitg00/skillkit

Related

Questions about Red Green Refactor