tdd

tdd is a skill for Codex from wangmiaozero/pi-harness. It costs 33 tokens per session (756 once invoked), scanned A, original, AGPL-3.0.

A guide to test-driven development, or TDD: writing a test that fails, making the code pass, and then improving the code. It is intended for feature work or bug fixes done test-first.

In plain words
What is it for?
Building features or fixing bugs with the red-green-refactor cycle, and writing integration tests.
Why use it?
It gives the agent a repeatable way to define expected behavior before changing implementation. This helps expose regressions and keeps the code tied to tested requirements.

Skill for Codex

Written for Codex: agents/openai.yaml present.

Good fit Building features or fixing bugs with the red-green-refactor cycle, and writing integration tests.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/wangmiaozero/pi-harness/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 wangmiaozero/pi-harness --skill tdd
Clone the repo
git clone --depth 1 https://github.com/wangmiaozero/pi-harness

Made for: Codex.

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/wangmiaozero/pi-harness/tdd/github.svg)](https://agentmods.dev/skills/wangmiaozero/pi-harness/tdd)
Your own site
<a href="https://agentmods.dev/skills/wangmiaozero/pi-harness/tdd"><img src="https://agentmods.dev/badge/skills/wangmiaozero/pi-harness/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 tdd

Your own site · 80×15
<a href="https://agentmods.dev/skills/wangmiaozero/pi-harness/tdd"><img src="https://agentmods.dev/badge/skills/wangmiaozero/pi-harness/tdd.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 756 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 $0.00033 $0.00756
Opus 5 $0.00016 $0.00378
Sonnet 5 $0.00007 $0.00151
Haiku 4.5 $0.00003 $0.00076

Measured 9d ago against content hash cb01f66bebfa, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, 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 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.

resources/builtin-skills/mattpocock/skills/engineering/tdd/SKILL.md · 39 lines

The source is not reproduced here

Licensed AGPL-3.0

The repository is licensed AGPL-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

3 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 · 39 lines · 33 tokens per session scan A cb01f66bebfa

Subscribe to this mod's changes

tdd is a skill published in the GitHub repository wangmiaozero/pi-harness (54 stars, last pushed 2d ago), licensed AGPL-3.0. It adds 33 tokens to every session and 756 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 2026-08-30.