Agent skill

Test Driven Development

Write software using the RED-GREEN-REFACTOR cycle for reliable, well-tested code

Apache-2.0Auto-check passedTesting & QA

Install Test Driven Development

skills CLI

$ npx skills add taracodlabs/aiden --skill test-driven-development -a claude-code

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

GitHub CLI

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

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 taracodlabs/aiden --skill test-driven-development -a codex

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

GitHub CLI

$ gh skill install taracodlabs/aiden test-driven-development --agent codex

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

Manual copy

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

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

GitHub CLI

$ gh skill install taracodlabs/aiden test-driven-development --agent cursor

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

Manual copy

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

--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 taracodlabs/aiden --skill test-driven-development -a gemini-cli

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

GitHub CLI

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

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 taracodlabs/aiden --skill test-driven-development -a github-copilot

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

Manual copy

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

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

Manual copy

$ git clone --depth 1 https://github.com/taracodlabs/aiden.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/test-driven-development .opencode/skills/test-driven-development && 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 "test-driven-development" agent skill from https://github.com/taracodlabs/aiden/tree/main/skills/test-driven-development into .opencode/skills/test-driven-development/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "test-driven-development", 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: test-driven-development
GitHub stars: 849
Token cost: ~1.1k tokens
SKILL.md length: 319 words
Files: 2
Skills in repo: 63
Repo updated: Sep 13, 2026
First seen: Oct 7, 2026
Licence: Apache-2.0

At a glance

Write software using the RED-GREEN-REFACTOR cycle for reliable, well-tested code

Works in 3 steps: RED — Write a failing test first → GREEN — Minimal implementation to pass → REFACTOR — Improve code quality
Tasks that involve Test-driven development
SKILL.md covers When to Use, How to Use, Examples and Cautions
Calls pytest

What it does

Test Driven Development is an agent skill from taracodlabs/aiden. Write software using the RED-GREEN-REFACTOR cycle for reliable, well-tested code

Its SKILL.md is about 1.1k tokens, which your agent loads only when the skill is triggered. The skill folder holds 1 other file (for example `skill.json`).

It sits in Testing & QA, covering Test-driven development and Unit testing. The repository describes itself as: Aiden — an autonomous AI agent and work engine built solo. It can operate your browser, terminal, files, apps, APIs, skills and tools, remember context, recover from failures… The licence is Apache-2.0.

When your agent uses it

Tasks that involve Test-driven development
Tasks that involve Unit testing

Example prompts

“/test-driven-development”

Requirements

Python 3

Workflow steps

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

RED — Write a failing test first
GREEN — Minimal implementation to pass
REFACTOR — Improve code quality

What it can do on your machine

Read from SKILL.md and the folder at commit 3704204. 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
Shell commands in SKILL.md call:
- pytest
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

Test Driven Development loads about 1.1k tokens when it runs. Until then it costs about 26 tokens; SKILL.md has 319 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~26
When it runs · the whole SKILL.md, loaded when a task matches: ~1.1k

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 taracodlabs/aiden at commit 3704204, republished under its Apache-2.0 licence (© taracodlabs). 319 words, ~1,139 tokens.

Download SKILL.mdSave it as .claude/skills/test-driven-development/SKILL.md (or your agent's skills folder). This skill also uses 1 other file; get the full folder from GitHub.

name: test-driven-development
description: Write software using the RED-GREEN-REFACTOR cycle for reliable, well-tested code
category: developer
version: 1.0.0
origin: aiden
license: Apache-2.0
tags: tdd, testing, red-green-refactor, unit-tests, pytest, jest, vitest, quality, development

Test-Driven Development (TDD)

Use the RED-GREEN-REFACTOR cycle to write reliable, well-tested software. Write tests first, then write the minimal code to pass them, then clean up.

When to Use

User wants to implement a new function or module correctly
User wants to ensure edge cases are handled before they become bugs
User is refactoring and wants a safety net
User wants tests for business-critical logic
User wants to document behavior through executable tests

How to Use

The TDD cycle

RED    → Write a failing test for the behavior you want
GREEN  → Write the minimum code to make the test pass
REFACTOR → Clean up the code without breaking tests
Repeat for each small behavior increment

Phase 1: RED — Write a failing test first

Write the test before the implementation. It must fail to prove the test works.

python

# test_calculator.py — write this BEFORE calculator.py
import pytest
from calculator import add

def test_add_two_positive_numbers():
  assert add(2, 3) == 5

def test_add_negative_number():
  assert add(-1, 5) == 4

def test_add_floats():
  assert abs(add(0.1, 0.2) - 0.3) < 1e-9

Run the tests — they should fail with ModuleNotFoundError or ImportError:

powershell

pytest test_calculator.py -v
# Expected: FAILED (module not found)

Phase 2: GREEN — Minimal implementation to pass

Write only enough code to make the tests pass — nothing more.

python

# calculator.py
def add(a, b):
  return a + b

powershell

pytest test_calculator.py -v
# Expected: 3 PASSED

Phase 3: REFACTOR — Improve code quality

Clean up implementation and tests while keeping all tests green.

python

# calculator.py — add type hints and docstring
def add(a: float, b: float) -> float:
  """Return the sum of a and b."""
  return a + b

powershell

pytest test_calculator.py -v  # must still pass after refactor

Write tests with pytest (Python)

python

# Parametrize for multiple cases
@pytest.mark.parametrize("a,b,expected", [
  (2, 3, 5),
  (-1, 5, 4),
  (0, 0, 0),
  (1.5, 2.5, 4.0),
])
def test_add(a, b, expected):
  assert add(a, b) == expected

# Test exceptions
def test_add_rejects_string():
  with pytest.raises(TypeError):
    add("hello", 2)

Write tests with Vitest / Jest (TypeScript / JavaScript)

typescript

// calculator.test.ts
import { describe, it, expect } from 'vitest'
import { add } from './calculator'

describe('add()', () => {
  it('adds two positive numbers', () => {
    expect(add(2, 3)).toBe(5)
  })

  it('handles negative numbers', () => {
    expect(add(-1, 5)).toBe(4)
  })

  it('throws on non-number input', () => {
    expect(() => add('a' as any, 2)).toThrow()
  })
})

TDD for API endpoints

python

# test_api.py — RED first
def test_create_user_returns_201(client):
  resp = client.post("/users", json={"name": "Alice", "email": "alice@example.com"})
  assert resp.status_code == 201
  assert resp.json()["id"] is not None

def test_create_user_rejects_missing_email(client):
  resp = client.post("/users", json={"name": "Alice"})
  assert resp.status_code == 422

# Then implement the /users endpoint to make these pass

Examples

"Implement a function that validates Indian phone numbers" → RED: write tests for +91 10-digit numbers, reject 9-digit, reject letters. GREEN: implement regex. REFACTOR: add named groups, docstring.

"Add a discount calculator to the checkout module" → RED: test 10% off, 0% off, 100% off, reject negative discount. GREEN: minimal implementation. REFACTOR: extract constants, add type hints.

"I want to refactor this function but keep it working" → Write characterization tests first (tests that document current behavior), then refactor with test safety net.

Cautions

Never skip the RED phase — a test that was never failing might not actually test anything
Tests should be independent — each test must set up its own state and not depend on test order
Aim for one assertion per test — tests with multiple assertions are harder to diagnose when they fail
TDD is slower upfront but faster overall — set this expectation with the user
Mock external services (APIs, databases) in unit tests — test real integrations separately

Files

SKILL.md and 1 other file in skills/test-driven-development of taracodlabs/aiden.

SKILL.md
skill.json

Open the folder on GitHubat commit 3704204

Compare with similar skills

Test Driven Development 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.

Test Driven Development compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Test Driven Development this skilltaracodlabs/aiden	849	—	~1.1k	Automated safety check: Pass	Apache-2.0	24 days ago
TDD WorkflowhellangleZ/burn-in-cceverywhere-ralph	112	11 repos	~2.4k	Automated safety check: Pass	None	8 mo ago
TDD Workflowaffaan-m/ECC	274k	3 repos	~2k	Automated safety check: Pass	MIT	2 days ago
TDD Workflowaffaan-m/ECC	274k	2 repos	~2k	Automated safety check: Pass	MIT	2 days ago
TDD Workflowaffaan-m/ECC	274k	2 repos	~2.1k	Automated safety check: Pass	MIT	2 days ago
TDD Workflowaffaan-m/ECC	274k	1 repos	~2.6k	Automated safety check: Pass	MIT	2 days ago

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Questions about Test Driven Development

What does Test Driven Development do?

Write software using the RED-GREEN-REFACTOR cycle for reliable, well-tested code. Test Driven Development is an agent skill from taracodlabs/aiden.

When should I use Test Driven Development?

Test Driven Development fits situations like: tasks that involve Test-driven development; tasks that involve Unit testing.

How do I install Test Driven Development in Claude Code?

Run `npx skills add taracodlabs/aiden --skill test-driven-development -a claude-code`. Or copy the skill folder (skills/test-driven-development in taracodlabs/aiden) into .claude/skills/test-driven-development in your project. Claude Code loads it when a task matches its description.

How do I install Test Driven Development in Codex?

Run `npx skills add taracodlabs/aiden --skill test-driven-development -a codex`. Or copy the skill folder (skills/test-driven-development in taracodlabs/aiden) into .agents/skills/test-driven-development in your project. Codex loads it when a task matches its description.

Can I use Test Driven Development 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 taracodlabs/aiden --skill test-driven-development -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/test-driven-development, .gemini/skills/test-driven-development, .github/skills/test-driven-development and .opencode/skills/test-driven-development in your project.

What does Test Driven Development need to run?

Going by SKILL.md and its folder, Test Driven Development needs the command-line tools its instructions call (pytest). Our summary lists: Python 3.

Does Test Driven Development 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 Test Driven Development 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 Test Driven Development use?

Test Driven Development is published under the Apache-2.0 licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Test Driven Development use?

About 1.1k tokens (SKILL.md is roughly 4.6k 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 Test Driven Development?

Skills that share tags, products or a category with Test Driven Development: TDD Workflow (hellangleZ/burn-in-cceverywhere-ralph, 112 stars), TDD Workflow (affaan-m/ECC, 274k stars), TDD Workflow (affaan-m/ECC, 274k stars) and TDD Workflow (affaan-m/ECC, 274k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Test Driven Development?

taracodlabs (a GitHub organization) maintains it in taracodlabs/aiden, which has 849 GitHub stars. The repository holds 63 skills in this directory. The repository was last updated on September 13, 2026.

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

Install Test Driven Development

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Test-Driven Development (TDD)

When to Use

How to Use

The TDD cycle

Phase 1: RED — Write a failing test first

Phase 2: GREEN — Minimal implementation to pass

Phase 3: REFACTOR — Improve code quality

Write tests with pytest (Python)

Write tests with Vitest / Jest (TypeScript / JavaScript)

TDD for API endpoints

Examples

Cautions

Files

Compare with similar skills

Similar skills

More from taracodlabs/aiden

Related

Questions about Test Driven Development