outside-in-tdd

outside-in-tdd is a skill for Claude Code from SebastienDegodez/skraft-plugin. It costs 173 tokens per session (5,168 once invoked), scanned A, original, GPL-3.0.

A testing guide for building software from an approved example or expected result. Outside-in, double-loop TDD means starting with a test at the application's boundary, then letting the failing behaviour guide the implementation.

In plain words
What is it for?
Use it to turn acceptance scenarios, Gherkin examples, or worked examples into working software through acceptance tests and smaller domain-level tests.
Why use it?
It prevents code from being written before the expected behaviour is tested and provides evidence that the initial test really fails.

Skill for Claude Code

Written for Claude Code: shipped in a Claude Code plugin.

Part of the skraft plugin — 36 skills, 15 agents, 5 hooks shipped together

Good fit Use it to turn acceptance scenarios, Gherkin examples, or worked examples into working software through acceptance tests and smaller domain-level tests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/sebastiendegodez/skraft-plugin/outside-in-tdd
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.

Any agent
npx skills add SebastienDegodez/skraft-plugin --skill outside-in-tdd
Clone the repo
git clone --depth 1 https://github.com/SebastienDegodez/skraft-plugin

Made for: Claude Code.

Or install skraft, the plugin that ships this one along with the rest of its 36 skills, 15 agents, 5 hooks.

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 outside-in-tdd

README.md
[![agentmods](https://agentmods.dev/badge/skills/sebastiendegodez/skraft-plugin/outside-in-tdd/github.svg)](https://agentmods.dev/skills/sebastiendegodez/skraft-plugin/outside-in-tdd)
Your own site
<a href="https://agentmods.dev/skills/sebastiendegodez/skraft-plugin/outside-in-tdd"><img src="https://agentmods.dev/badge/skills/sebastiendegodez/skraft-plugin/outside-in-tdd/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for outside-in-tdd

Your own site · 80×15
<a href="https://agentmods.dev/skills/sebastiendegodez/skraft-plugin/outside-in-tdd"><img src="https://agentmods.dev/badge/skills/sebastiendegodez/skraft-plugin/outside-in-tdd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 173 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 5,168 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
Origin unknown 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 $0.00173 $0.05168
Opus 5 $0.00086 $0.02584
Sonnet 5 $0.00035 $0.01034
Haiku 4.5 $0.00017 $0.00517

Measured 9d ago against content hash a56cf6d21871, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

outside-in-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 9d 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.

plugins/skraft-framework/skills/outside-in-tdd/SKILL.md · 400 lines

The source is not reproduced here

Licensed GPL-3.0

The repository is licensed GPL-3.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

Files

What ships with it

5 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 9d ago First seen · 400 lines · 173 tokens per session scan A a56cf6d21871

Subscribe to this mod's changes

outside-in-tdd is a skill published in the GitHub repository SebastienDegodez/skraft-plugin (8 stars, last pushed 5d ago), licensed GPL-3.0. It adds 173 tokens to every session and 5,168 once invoked, about $0.0009 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 2026-09-03.

Related

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