tdd

tdd is a skill for Claude Code from forest6511/claude-code-recipes-v2. It costs 27 tokens per session (504 once invoked), scanned A, original, MIT.

A guided implementation process using test-driven development, or TDD. TDD writes a failing test first, adds the smallest code needed to pass it, and then improves the code while keeping the test passing.

In plain words
What is it for?
Building a feature one small behavior at a time through the Red, Green, and Refactor stages, with user confirmation required before moving to the next stage.
Why use it?
It keeps each change tied to a concrete expected behavior and limits unnecessary implementation. The process also checks that existing tests continue to pass.

Skill for Claude Code

Written for Claude Code: allowed-tools in frontmatter.

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/forest6511/claude-code-recipes-v2/tdd
Any agent
npx skills add forest6511/claude-code-recipes-v2 --skill tdd
Clone the repo
git clone --depth 1 https://github.com/forest6511/claude-code-recipes-v2

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for tdd

README.md
[![agentmods](https://agentmods.dev/badge/skills/forest6511/claude-code-recipes-v2/tdd.svg)](https://agentmods.dev/skills/forest6511/claude-code-recipes-v2/tdd)
Your own site
<a href="https://agentmods.dev/skills/forest6511/claude-code-recipes-v2/tdd"><img src="https://agentmods.dev/badge/skills/forest6511/claude-code-recipes-v2/tdd.svg" alt="Measured on agentmods" height="20"></a>
Per session 27 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 504 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00027 $0.00504
Opus 5 $0.00014 $0.00252
Sonnet 5 $0.00005 $0.00101
Haiku 4.5 $0.00003 $0.00050

Measured 6d ago against content hash e2b11d7c4ab2, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

tdd scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

ch08-skills-templates/recipe-41/.claude/skills/tdd/SKILL.md · 34 lines

What it actually says

実装したい機能: $ARGUMENTS

TDD のサイクルに従い、各フェーズでユーザーの確認を待って次へ進みます。

Phase 1: Red — 失敗するテストを書く

  1. 機能の最小単位を1つ選び、それに対するテストを書く
  2. テストを実行し、期待通りに失敗することを確認する (npm test / pytest / go test)
  3. 失敗メッセージと、次に Green で実装すべき最小スコープをユーザーに報告

Phase 2: Green — テストを通す最小実装

  1. Phase 1 のテストを通すための最小限のコードだけ書く
  2. テストを実行し、対象テストが通ることを確認する
  3. 既存テストが壊れていないことも合わせて確認
  4. 結果をユーザーに報告

Phase 3: Refactor — 重複の除去と命名の調整

  1. Phase 2 で書いたコードと既存コードの間に重複がないか調査
  2. 命名・関数長・責務分離を見直す
  3. 各リファクタ後にテストを実行し、Green を維持
  4. 完了をユーザーに報告し、次の機能単位に進むか確認

守るべきルール

  • フェーズの順序は厳守。Green の前に余計な実装を進めない
  • 各フェーズの最後に必ずテストを実行し、状態を報告する
  • ユーザーから「次へ」と指示がない限り次のフェーズに進まない
Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 34 lines · 27 tokens per session scan A e2b11d7c4ab2

Subscribe to this mod's changes

tdd is a skill published in the GitHub repository forest6511/claude-code-recipes-v2 (5 stars, last pushed 4mo ago), licensed MIT. It adds 27 tokens to every session and 504 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.