A test-planning tool for large or complex software changes. It creates a standalone test suite covering detailed cases, test data, reusable test setups, full user flows, parallel work, and deliberate attempts to find weaknesses.

Use it for Full-tier features with interactions across multiple parts of an application, especially when developers need a test plan to guide implementation.

Writing tests only while coding can make teams test the implementation instead of the promised behavior. Planning them first exposes missing edge cases and testing needs before code is written.

test-plan — Skill for Claude Code by diegoesolorzano

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 diegoesolorzano/spec-plan-ship --skill test-plan

Clone the repo

git clone --depth 1 https://github.com/diegoesolorzano/spec-plan-ship

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.

README.md

[![agentmods](https://agentmods.dev/badge/skills/diegoesolorzano/spec-plan-ship/test-plan.svg)](https://agentmods.dev/skills/diegoesolorzano/spec-plan-ship/test-plan)

Your own site

<a href="https://agentmods.dev/skills/diegoesolorzano/spec-plan-ship/test-plan"><img src="https://agentmods.dev/badge/skills/diegoesolorzano/spec-plan-ship/test-plan.svg" alt="Measured on agentmods" height="20"></a>

Per session 106 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 2,683 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.

Model	Per session	Once invoked
Fable 5.1	$0.00106	$0.02683
Opus 5	$0.00053	$0.01341
Sonnet 5	$0.00021	$0.00537
Haiku 4.5	$0.00011	$0.00268

Measured 7d ago against content hash 4808e8dbd576, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-07, from the pricing page.

Security

Grade A, and why

test-plan 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 7d 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.

skills/test-plan/SKILL.md · 317 lines

How it starts

The opening of the file, as written. The whole thing — 317 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Test Plan

Tier Guard (first)

Read the plan's **Tier:** metadata (or the spec's). This skill applies to Full-tier changes only (or a change promoted to Full). If the tier is Standard or Lite, STOP and reply: "test-plan applies only to Full tier; the plan's embedded Test Matrix is the test artifact. A Standard operational feature invokes /operational-test-plan directly from the plan." Do not produce an artifact.

You are a QA Architect. Your job is to design the complete test suite for a feature BEFORE any implementation code is written. You read the approved plan, understand the contracts, and produce a test plan that the /tdd skill consumes during implementation.

Why This Phase Exists

Writing tests ad-hoc during implementation introduces bias — you test what you built, not what you should have built. By designing all test cases upfront from the plan's contracts and spec's acceptance criteria, you:

Catch missing edge cases before code exists
Validate that the plan's typed signatures are actually testable
Identify test infrastructure needs early (fixtures, seeds, mocks for external APIs)
Enable parallel implementation — developers can split test files and work independently

Procedure

Step 1: Load the Plan

If the user provided a file path as argument, read it.
If no argument, look in docs/specs/ for the most recent plan file.
If multiple plans exist, ask which one to use.
Also read the corresponding spec from docs/specs/ (referenced in the plan's header).

Step 2: Discover Test Infrastructure

Before designing tests, understand what exists:

Test framework — Look for test config files (vitest.config, jest.config, pytest.ini, phpunit.xml, *.test.*, *.spec.*). Identify the framework and conventions.
Existing test patterns — Read 2-3 existing test files to understand naming, structure, helper usage, and assertion style.
Test utilities — Check for test helpers, factories, fixtures, seeds, or custom matchers.
Database test strategy — Check if tests use a test database, transactions, or cleanup hooks.
E2E setup — Check for Playwright, Cypress, or similar E2E infrastructure.

Read the full file on GitHub · 317 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.

7d ago First seen · 317 lines · 106 tokens per session scan A 4808e8dbd576

Subscribe to this mod's changes

test-plan is a skill published in the GitHub repository diegoesolorzano/spec-plan-ship (5 stars, last pushed 3d ago), licensed MIT. It adds 106 tokens to every session and 2,683 once invoked, about $0.0005 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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test-plan