test-author

test-author is a skill for Claude Code, Codex from hams-ollo/zen-agent-skills. It costs 154 tokens per session (2,039 once invoked), scanned A, original, MIT.

A test-writing skill that turns approved specification scenarios into runnable tests, using one test for each Given/When/Then scenario and its stable identifier. Given/When/Then is a format describing setup, action, and expected result.

In plain words
What is it for?
Use it after implementation to create scenario-based tests, add characterization tests for existing behavior, or cover a bug with a regression test.
Why use it?
It links tests directly to the behavior the specification requires, making failures easier to trace. It stops if the specification has not been approved.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one. Also seen: installed under .agents/ (shared by several agents).

Good fit Use it after implementation to create scenario-based tests, add characterization tests for existing behavior, or cover a bug with a regression test.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/hams-ollo/zen-agent-skills/test-author
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 hams-ollo/zen-agent-skills --skill test-author
Clone the repo
git clone --depth 1 https://github.com/hams-ollo/zen-agent-skills

Made for: Claude Code, 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 test-author

README.md
[![agentmods](https://agentmods.dev/badge/skills/hams-ollo/zen-agent-skills/test-author/github.svg)](https://agentmods.dev/skills/hams-ollo/zen-agent-skills/test-author)
Your own site
<a href="https://agentmods.dev/skills/hams-ollo/zen-agent-skills/test-author"><img src="https://agentmods.dev/badge/skills/hams-ollo/zen-agent-skills/test-author/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-author

Your own site · 80×15
<a href="https://agentmods.dev/skills/hams-ollo/zen-agent-skills/test-author"><img src="https://agentmods.dev/badge/skills/hams-ollo/zen-agent-skills/test-author.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 154 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,039 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 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 $0.00154 $0.02039
Opus 5 $0.00077 $0.01019
Sonnet 5 $0.00031 $0.00408
Haiku 4.5 $0.00015 $0.00204

Measured 5d ago against content hash f0b00e5f90a1, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-09, from the pricing page.

Security

Grade A, and why

test-author 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 5d 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.

.agents/skills/test-author/SKILL.md · 155 lines

How it starts

The opening of the file, as written. The whole thing — 155 lines — stays where its author put it; the contents beside it link to each section on GitHub.

test-author

Turn an approved spec into runnable, traceable tests. This is the only spine skill that actually authors tests: test-quality judges test design, spec-conformance audits whether code matches a spec, and fix-batch runs whatever tests exist. test-author is what produces them, from the contract, so that a failing test points back to the exact scenario it protects.

It runs after implementation and before reconciliation, so test evidence is available when changes are verified and landed. It composes two lenses by reference and does not restate their rules: spec-quality gates the input spec, and test-quality governs every layer and oracle choice.

When to use

  • An implementation exists (or a surface is defined) and its approved spec's scenarios need tests.
  • Legacy code has no coverage and needs its current behavior pinned before a change (characterization).
  • A bug fix needs a regression test that provably fails on the buggy behavior.

When not to use

  • You only need to judge whether an existing test is worth keeping: use test-quality.
  • You need to check whether the code matches the spec by inspection, not by writing tests: use spec-conformance.
  • No spec and no legacy code to characterize: there is nothing to derive tests from yet.

Modes

  • Acceptance (an approved spec is present): derive tests from the spec's scenarios.
  • Characterization (legacy code, no spec): assert the current observable behavior to pin it before a change, and label the tests as characterization in the name or an adjacent comment.

Infer the mode from the inputs, and let the user override it.

Inputs

Required (acceptance mode):

  • Approved spec: a readable spec with status: approved and Given/When/Then scenarios carrying stable S-NNN ids.

Read the full file on GitHub · 155 lines

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. 5d ago Changed · +7 lines f0b00e5f90a1
  2. 9d ago First seen · 148 lines · 154 tokens per session scan A d64caeae32f7

Subscribe to this mod's changes

test-author is a skill published in the GitHub repository hams-ollo/zen-agent-skills (2 stars, last pushed 7d ago), licensed MIT. It adds 154 tokens to every session and 2,039 once invoked, about $0.0008 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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