test-driven-development

test-driven-development is a skill for Claude Code from Pyroxin/opinionated-claude-skills. It costs 43 tokens per session (2,359 once invoked), scanned A, original, EPL-2.0.

A guide to test-driven development, or TDD: writing a test that describes expected behavior before implementing the code. It treats tests as agreements about what the software should do.

In plain words
What is it for?
Use it when writing tests interactively, choosing what to test, deciding where to mock dependencies, or fixing code that fails its tests.
Why use it?
It helps catch regressions and keeps tests focused on observable behavior rather than fragile internal details.

Skill for Claude Code

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

Part of the opinionated-software-engineering plugin — 6 skills shipped together

Good fit Use it when writing tests interactively, choosing what to test, deciding where to mock dependencies, or fixing code that fails its tests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/pyroxin/opinionated-claude-skills/test-driven-development
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 Pyroxin/opinionated-claude-skills --skill test-driven-development
Clone the repo
git clone --depth 1 https://github.com/Pyroxin/opinionated-claude-skills

Made for: Claude Code.

Or install opinionated-software-engineering, the plugin that ships this one along with the rest of its 6 skills.

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 test-driven-development

README.md
[![agentmods](https://agentmods.dev/badge/skills/pyroxin/opinionated-claude-skills/test-driven-development/github.svg)](https://agentmods.dev/skills/pyroxin/opinionated-claude-skills/test-driven-development)
Your own site
<a href="https://agentmods.dev/skills/pyroxin/opinionated-claude-skills/test-driven-development"><img src="https://agentmods.dev/badge/skills/pyroxin/opinionated-claude-skills/test-driven-development/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 test-driven-development

Your own site · 80×15
<a href="https://agentmods.dev/skills/pyroxin/opinionated-claude-skills/test-driven-development"><img src="https://agentmods.dev/badge/skills/pyroxin/opinionated-claude-skills/test-driven-development.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 43 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,359 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 $0.00043 $0.02359
Opus 5 $0.00022 $0.01179
Sonnet 5 $0.00009 $0.00472
Haiku 4.5 $0.00004 $0.00236

Measured 9d ago against content hash 2998f45aaadb, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

test-driven-development 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.

opinionated-software-engineering/skills/test-driven-development/SKILL.md · 235 lines

The source is not reproduced here

Licensed EPL-2.0

The repository is licensed EPL-2.0, which this catalogue does not treat as permission to reproduce the file. Read it at the source.

Read it on GitHub

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 · 235 lines · 43 tokens per session scan A 2998f45aaadb

Subscribe to this mod's changes

test-driven-development is a skill published in the GitHub repository Pyroxin/opinionated-claude-skills (9 stars, last pushed 2d ago), licensed EPL-2.0. It adds 43 tokens to every session and 2,359 once invoked, about $0.0002 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.

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Take one new feature slice from idea to reviewed, committed code in a single guided pass — scope it into the smallest shippable slice, build it test-first with strict TDD, review and fix the diff, then commit it. Chains slice → test-driven-development → the built-in /code-review → git-commit. Not for reviewing an…

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