write-tests

write-tests is a skill for Claude Code from leifericf/agentic-sdk. It costs 46 tokens per session (4,051 once invoked), scanned A, original, MIT.

A testing guide for choosing the right test level, from pure functions to full end-to-end behavior. It also covers property-based tests, which check many generated inputs against general rules.

In plain words
What is it for?
Use it when writing unit, integration, or end-to-end tests and deciding which parts of a project need each kind of test.
Why use it?
It helps prevent gaps in test coverage and keeps test descriptions focused on observable behavior rather than internal workflow.

Skill for Claude Code

Written for Claude Code: user-invocable in frontmatter.

Good fit Use it when writing unit, integration, or end-to-end tests and deciding which parts of a project need each kind of test.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/leifericf/agentic-sdk/write-tests
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 leifericf/agentic-sdk --skill write-tests
Clone the repo
git clone --depth 1 https://github.com/leifericf/agentic-sdk

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.

agentmods badge for write-tests

README.md
[![agentmods](https://agentmods.dev/badge/skills/leifericf/agentic-sdk/write-tests.svg)](https://agentmods.dev/skills/leifericf/agentic-sdk/write-tests)
Your own site
<a href="https://agentmods.dev/skills/leifericf/agentic-sdk/write-tests"><img src="https://agentmods.dev/badge/skills/leifericf/agentic-sdk/write-tests.svg" alt="Measured on agentmods" height="20"></a>
Per session 46 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 4,051 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 $0.00046 $0.04051
Opus 5 $0.00023 $0.02025
Sonnet 5 $0.00009 $0.00810
Haiku 4.5 $0.00005 $0.00405

Measured 4d ago against content hash 2c9d6b58b1bd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-08, from the pricing page.

Security

Grade A, and why

write-tests 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 4d 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/write-tests/SKILL.md · 357 lines

How it starts

The opening of the file, as written. The whole thing — 357 lines — stays where its author put it; the contents beside it link to each section on GitHub.

write-tests

Write tests for the project. The deep taxonomy (the four engines of exhaustiveness, the leak lane, the coverage loop, compile-once fixtures across the boundary, the surface-to-tier map) lives in skills/shared/references/pyramid.md; read it before writing anything past a single unit test. This file is the hub: pick the surface, follow the rules, commit green.

Test names, context strings, and fixture comments are prose; invoke write-prose. Describe behavior, never process: no phase, task, slice, or run id in a test description.

Pick the surface first

The suite mirrors the source layout. The pure core carries the bulk; shell and native carry fewer, heavier integration tests. The four surfaces map onto the tiers in pyramid.md:

  • Pure core. Plain data in, data out. No mocks, no fixtures beyond literal values. This is where correctness is decided and where the architectural commitments live: description-not-instruction, plain data, the standalone module that requires no other. Most of the suite is here.
  • Native round-trip. An integration test that builds the native side, loads the result, and asserts the returned value or the handle's observable state. Real native code, real external libraries, real cache. Never mock the toolchain.
  • Persistence and shell. An integration test that stands up a scratch store under a test-owned temp path, installs the schema (or equivalent), writes, and reads back. Round-trip every mutation through a real transaction (or store call); never mock the peer API. Assert history where the store keeps it: as-of and since queries see retractions.
  • Generated source. A function that emits source another engine executes (Datalog, SQL, a wire payload, native source) is asserted as a string for syntax, and run through the owning engine for behavior (see below).

When in doubt which tier a behavior needs, read the surface map in pyramid.md.

The tools, language-neutral

The project's descriptor names the concrete tools; the roles are stable across them.

Read the full file on GitHub · 357 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. 4d ago First seen · 357 lines · 46 tokens per session scan A 2c9d6b58b1bd

Subscribe to this mod's changes

write-tests is a skill published in the GitHub repository leifericf/agentic-sdk (5 stars, last pushed 6d ago), licensed MIT. It adds 46 tokens to every session and 4,051 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 2026-09-03.

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