Agent skill

TDD

Systematic TDD methodology for writing tests first. An agent skill from TechDufus/oh-my-claude.

MITAuto-check passedTesting & QA

Install TDD

skills CLI

$ npx skills add TechDufus/oh-my-claude --skill tdd -a claude-code

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

GitHub CLI

$ gh skill install TechDufus/oh-my-claude tdd --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/TechDufus/oh-my-claude.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/oh-my-claude/skills/tdd .claude/skills/tdd && 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 "tdd" agent skill from https://github.com/TechDufus/oh-my-claude/tree/main/plugins/oh-my-claude/skills/tdd into .claude/skills/tdd/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "tdd", 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/TechDufus/oh-my-claude/tree/main/plugins/oh-my-claude/skills/tdd

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 TechDufus/oh-my-claude --skill tdd -a codex

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

GitHub CLI

$ gh skill install TechDufus/oh-my-claude tdd --agent codex

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

Manual copy

$ git clone --depth 1 https://github.com/TechDufus/oh-my-claude.git skills-src && mkdir -p .agents/skills && cp -r skills-src/plugins/oh-my-claude/skills/tdd .agents/skills/tdd && 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 "tdd" agent skill from https://github.com/TechDufus/oh-my-claude/tree/main/plugins/oh-my-claude/skills/tdd into .agents/skills/tdd/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "tdd", 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 TechDufus/oh-my-claude --skill tdd -a cursor

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

GitHub CLI

$ gh skill install TechDufus/oh-my-claude tdd --agent cursor

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

Manual copy

$ git clone --depth 1 https://github.com/TechDufus/oh-my-claude.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/plugins/oh-my-claude/skills/tdd .cursor/skills/tdd && 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 "tdd" agent skill from https://github.com/TechDufus/oh-my-claude/tree/main/plugins/oh-my-claude/skills/tdd into .cursor/skills/tdd/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "tdd", 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/TechDufus/oh-my-claude.git --path plugins/oh-my-claude/skills/tdd

--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 TechDufus/oh-my-claude --skill tdd -a gemini-cli

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

GitHub CLI

$ gh skill install TechDufus/oh-my-claude tdd --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/TechDufus/oh-my-claude.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/plugins/oh-my-claude/skills/tdd .gemini/skills/tdd && 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 "tdd" agent skill from https://github.com/TechDufus/oh-my-claude/tree/main/plugins/oh-my-claude/skills/tdd into .gemini/skills/tdd/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "tdd", 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 TechDufus/oh-my-claude tdd

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 TechDufus/oh-my-claude --skill tdd -a github-copilot

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

Manual copy

$ git clone --depth 1 https://github.com/TechDufus/oh-my-claude.git skills-src && mkdir -p .github/skills && cp -r skills-src/plugins/oh-my-claude/skills/tdd .github/skills/tdd && 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 "tdd" agent skill from https://github.com/TechDufus/oh-my-claude/tree/main/plugins/oh-my-claude/skills/tdd into .github/skills/tdd/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "tdd", 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 TechDufus/oh-my-claude --skill tdd -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 TechDufus/oh-my-claude tdd --agent opencode

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

Manual copy

$ git clone --depth 1 https://github.com/TechDufus/oh-my-claude.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/plugins/oh-my-claude/skills/tdd .opencode/skills/tdd && 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 "tdd" agent skill from https://github.com/TechDufus/oh-my-claude/tree/main/plugins/oh-my-claude/skills/tdd into .opencode/skills/tdd/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "tdd", 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: tdd
GitHub stars: 174
Token cost: ~1k tokens
SKILL.md length: 601 words
Files: 1
Skills in repo: 12
Repo updated: Jul 13, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

Systematic TDD methodology for writing tests first. An agent skill from TechDufus/oh-my-claude.

Works in 4 steps: Write ONE test that describes the… → Run the test suite → Verify it fails for the RIGHT reason… → …
Implementing features
SKILL.md covers The Iron Law, When to Apply, Red-Green-Refactor Cycle and Anti-Rationalization Table, plus 4 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

TDD is an agent skill from TechDufus/oh-my-claude. Systematic TDD methodology for writing tests first. Use when implementing features or fixes with OMCTDDMODE enabled, when unsure how to structure tests, or when test-first discipline needs reinforcement. Triggers on: 'tdd', 'test first', 'test driven', 'red green refactor'.

Its SKILL.md is about 1k 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: Add ultrawork to any prompt for maximum parallel execution. The licence is MIT.

When your agent uses it

Implementing features
Fixes with OMCTDDMODE enabled
Unsure how to structure tests
Test-first discipline needs reinforcement

Example prompts

“test first”
“test driven”
“red green refactor”
“/tdd”

Workflow steps

4 steps, taken from the first numbered list in SKILL.md.

Write ONE test that describes the desired behavior
Run the test suite
Verify it fails for the RIGHT reason (not a syntax error, not a missing import)
If it passes, your test is wrong or the feature already exists

What it can do on your machine

Read from SKILL.md and the folder at commit ede75db. 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.
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

TDD loads about 1k tokens when it runs. Until then it costs about 70 tokens; SKILL.md has 601 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~70
When it runs · the whole SKILL.md, loaded when a task matches: ~1k

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 TechDufus/oh-my-claude at commit ede75db, republished under its MIT licence (© TechDufus). 601 words, ~1,047 tokens.

Download SKILL.mdSave it as .claude/skills/tdd/SKILL.md (or your agent's skills folder).

name: tdd
description: Systematic TDD methodology for writing tests first. Use when implementing features or fixes with OMC_TDD_MODE enabled, when unsure how to structure tests, or when test-first discipline needs reinforcement. Triggers on: 'tdd', 'test first', 'test driven', 'red green refactor'.

TDD Skill

Write the test. Watch it fail. Make it pass. Clean up. Repeat.

The Iron Law

NO PRODUCTION CODE WITHOUT A FAILING TEST FIRST

If you're writing production code and no test just failed, you're doing it wrong.

When to Apply

OMC_TDD_MODE is enabled (guided or enforced)
Implementing a new feature or behavior
Fixing a bug (write the test that reproduces it first)
Unsure how to structure tests for a piece of logic
When the tdd_enforcer hook blocks an edit

Red-Green-Refactor Cycle

RED: Write a Failing Test

Write ONE test that describes the desired behavior
Run the test suite
Verify it fails for the RIGHT reason (not a syntax error, not a missing import)
If it passes, your test is wrong or the feature already exists

Verification gate: Test output shows a meaningful failure related to the behavior you're implementing.

GREEN: Make It Pass

Write the MINIMUM code to make the test pass
No extra methods. No abstractions. No "while I'm here" additions
Run the test suite
ALL tests pass (not just the new one)

Verification gate: Full test suite green. Zero failures.

REFACTOR: Clean Up

Remove duplication introduced in the GREEN step
Improve naming, extract methods if warranted
Run the test suite after EVERY change
No new behavior during refactor - tests stay green throughout

Verification gate: Tests still green. Code is cleaner. No new functionality added.

Anti-Rationalization Table

Excuse	Counter
"I'll write tests after"	Tests written after prove nothing - they pass immediately
"Too simple to test"	Simple code breaks. Test takes 30 seconds
"I know this works"	Confidence is not evidence. The test IS the evidence
"Tests will slow me down"	Debugging without tests slows you down more
"Just a refactor"	Refactors without tests are rewrites without safety nets
"The types guarantee correctness"	Types check structure, not behavior. Test the behavior
"It's just a config change"	Config changes cause production outages. Test them
"I'll TDD the next one"	You said that last time. Start now

Show full SKILL.md (262 more words)Show less

Red Flags

Thoughts that signal you're about to violate TDD:

"Let me just quickly implement this first..."
"This is too obvious to need a test"
"I'll come back and add tests"
"The test would just be testing the framework"
"It's only a one-line change"
"I need to see the implementation to know what to test"

If you catch yourself thinking any of these: STOP. Write the test first.

Hook Integration

The tdd_enforcer hook gates file edits when OMC_TDD_MODE is enabled. This skill guides the methodology. The hook fires, you see the gate, invoke this skill for how to proceed.

Flow: Hook blocks edit -> Read the message -> Write/update a test -> Run tests (see RED) -> Now implement (GREEN) -> Clean up (REFACTOR).

When Stuck

Problem	Solution
Can't figure out what to test	Test the simplest case first. What's the most basic input/output?
Test is too complex	Break the behavior into smaller units. Test each one
Don't know the test framework	Check existing tests in the project. Copy the pattern
Test requires too much setup	That's a design smell. Simplify the interface under test
Multiple things need testing	One test at a time. Pick the smallest behavior first
Existing code has no tests	Start with the change you're making. Test the new behavior
Test passes immediately	Your test isn't testing what you think. Check assertions
Can't make the test fail	You might be testing something already implemented. Test the GAP

The Bottom Line

A test that exists before the code proves the code works. A test written after proves nothing but that you can reverse-engineer assertions.

Files

Just SKILL.md in plugins/oh-my-claude/skills/tdd of TechDufus/oh-my-claude.

Open the folder on GitHubat commit ede75db

Compare with similar skills

TDD 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.

TDD compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
TDD this skillTechDufus/oh-my-claude	174	—	~1k	Automated safety check: Pass	MIT	2 mo ago
TDDpietheinstrengholt/rssmonster	564	30 repos	~906	Automated safety check: Pass	MIT	today
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	16 days ago
Tapd Story PipelineTencentBlueKing/bk-bcs	840	—	~2.6k	Automated safety check: Pass	Custom licence	today

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Questions about TDD

What does TDD do?

Systematic TDD methodology for writing tests first. An agent skill from TechDufus/oh-my-claude. TDD is an agent skill from TechDufus/oh-my-claude. Systematic TDD methodology for writing tests first.

When should I use TDD?

TDD fits situations like: implementing features; fixes with OMCTDDMODE enabled; unsure how to structure tests; test-first discipline needs reinforcement.

How do I install TDD in Claude Code?

Run `npx skills add TechDufus/oh-my-claude --skill tdd -a claude-code`. Or copy the skill folder (plugins/oh-my-claude/skills/tdd in TechDufus/oh-my-claude) into .claude/skills/tdd in your project. Claude Code loads it when a task matches its description.

How do I install TDD in Codex?

Run `npx skills add TechDufus/oh-my-claude --skill tdd -a codex`. Or copy the skill folder (plugins/oh-my-claude/skills/tdd in TechDufus/oh-my-claude) into .agents/skills/tdd in your project. Codex loads it when a task matches its description.

Can I use TDD 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 TechDufus/oh-my-claude --skill tdd -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/tdd, .gemini/skills/tdd, .github/skills/tdd and .opencode/skills/tdd in your project.

What does TDD need to run?

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

Does TDD 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 TDD 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 TDD use?

TDD is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does TDD use?

About 1k tokens (SKILL.md is roughly 4.2k 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 TDD?

Skills that share tags, products or a category with TDD: 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 TDD?

TechDufus (a GitHub user) maintains it in TechDufus/oh-my-claude, which has 174 GitHub stars. The repository holds 12 skills in this directory. The repository was last updated on July 13, 2026.

Source: TechDufus/oh-my-claude on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install TDD

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

TDD Skill

The Iron Law

When to Apply

Red-Green-Refactor Cycle

RED: Write a Failing Test

GREEN: Make It Pass

REFACTOR: Clean Up

Anti-Rationalization Table

Red Flags

Hook Integration

When Stuck

The Bottom Line

Files

Compare with similar skills

Similar skills

More from TechDufus/oh-my-claude

Related

Questions about TDD