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Agent skill

TDD

by stevesolun in stevesolun/ctx

Apply test-driven development with small, behavior-focused feedback loops.

MITAuto-check passedTesting & QA

Install TDD

skills CLI
$ npx skills add stevesolun/ctx --skill tdd -a claude-code

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

GitHub CLI
$ gh skill install stevesolun/ctx 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/stevesolun/ctx.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.agents/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/

Facts

Skill name
tdd
GitHub stars
588
Token cost
~437 tokens
SKILL.md length
213 words
Files
4
Skills in repo
26
Repo updated
First seen
Licence
MIT

At a glance

Apply test-driven development with small, behavior-focused feedback loops.

  • Works in 5 steps: Identify one observable behavior and the… → Write the smallest meaningful test and… → Add only enough implementation to make… → …
  • The user asks to build
  • SKILL.md covers Loop and Judgment
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

TDD is an agent skill from stevesolun/ctx. Apply test-driven development with small, behavior-focused feedback loops. Use when the user asks to build or fix something test-first, mentions red-green-refactor, or wants integration tests.

Its SKILL.md is about 440 tokens, which your agent loads only when the skill is triggered. The skill folder holds 4 other files (for example `agents/openai.yaml`, `mocking.md` and `tests.md`).

It sits in Testing & QA, covering Test-driven development. The repository describes itself as: CTX Fit finds the cheapest AI coding setup that reliably works on your repository, then applies the winner as a reviewable change. The licence is MIT.

When your agent uses it

  • The user asks to build
  • Fix something test-first
  • Mentions red-green-refactor
  • Wants integration tests

Example prompts

  • “/tdd”

Workflow steps

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

  1. Identify one observable behavior and the seam through which callers see it.
  2. Write the smallest meaningful test and confirm that it fails for the expected
  3. Add only enough implementation to make the test pass.
  4. Refactor when doing so improves clarity or design; keep the suite green.
  5. Repeat with the next vertical slice.

What it can do on your machine

Read from SKILL.md and the folder at commit 11b582a. 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 437 tokens when it runs. Until then it costs about 49 tokens; SKILL.md has 213 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~49
When it runs · the whole SKILL.md, loaded when a task matches
~437

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 stevesolun/ctx at commit 11b582a, republished under its MIT licence (© stevesolun). 213 words, ~437 tokens.

Download SKILL.mdSave it as .claude/skills/tdd/SKILL.md (or your agent's skills folder). This skill also uses 3 other files; get the full folder from GitHub.
name
tdd
description
Apply test-driven development with small, behavior-focused feedback loops. Use when the user asks to build or fix something test-first, mentions red-green-refactor, or wants integration tests.

Test-Driven Development

Use small red → green → refactor cycles when a test-first feedback loop is practical. Treat repository conventions, existing tests, and the requested behavior as authoritative.

Loop

  1. Identify one observable behavior and the seam through which callers see it.
  2. Write the smallest meaningful test and confirm that it fails for the expected reason.
  3. Add only enough implementation to make the test pass.
  4. Refactor when doing so improves clarity or design; keep the suite green.
  5. Repeat with the next vertical slice.

Infer seams from public interfaces and nearby tests. Ask the user only when choosing a seam would materially change the product contract, cost, or scope.

Judgment

  • Prefer behavior-focused tests that survive internal refactors.
  • Derive expected results from a specification, worked example, or other independent source rather than duplicating the implementation.
  • Mock external or nondeterministic boundaries when useful; follow established repository patterns where they provide an adequate feedback loop.
  • Prefer vertical slices over a speculative batch of tests. Batch closely related mechanical cases when that is clearer and faster.
  • If a failing-first cycle is impractical—for example in legacy code with no usable seam—state the limitation and establish the nearest reliable characterization or integration test.

Read tests.md for examples and mocking.md when deciding whether and where to use test doubles.

© stevesolun, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 3 other files in .agents/skills/tdd of stevesolun/ctx.

  • SKILL.md
  • agents/openai.yaml
  • mocking.md
  • tests.md

Open the folder on GitHubat commit 11b582a

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
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
TDD this skillstevesolun/ctx588—~437Automated safety check: PassMIT
TDDpietheinstrengholt/rssmonster56430 repos~906Automated safety check: PassMIT
TDD WorkflowhellangleZ/burn-in-cceverywhere-ralph11211 repos~2.4kAutomated safety check: PassNone
TDDsanity-io/sanity6.4k20 repos~1kAutomated safety check: PassMIT
Test Driven Developmentfarm-fe/farm5.6k51 repos~2.5kAutomated safety check: PassMIT
Tapd Story PipelineTencentBlueKing/bk-bcs840—~2.6kAutomated safety check: PassCustom licence

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All 26 skills in this repo

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  • Code Review

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  • No Mistakes

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  • Skill Router

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  • Codebase Design

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Categories

Questions about TDD

What does TDD do?

Apply test-driven development with small, behavior-focused feedback loops. TDD is an agent skill from stevesolun/ctx. Apply test-driven development with small, behavior-focused feedback loops.

When should I use TDD?

TDD fits situations like: the user asks to build; fix something test-first; mentions red-green-refactor; wants integration tests.

How do I install TDD in Claude Code?

Run `npx skills add stevesolun/ctx --skill tdd -a claude-code`. Or copy the skill folder (.agents/skills/tdd in stevesolun/ctx) 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 stevesolun/ctx --skill tdd -a codex`. Or copy the skill folder (.agents/skills/tdd in stevesolun/ctx) 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 stevesolun/ctx --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 437 tokens (SKILL.md is roughly 1.7k 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?

stevesolun (a GitHub user) maintains it in stevesolun/ctx, which has 588 GitHub stars. The repository holds 26 skills in this directory. The repository was last updated on October 4, 2026.

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