write-tests

Guidance for writing unit and integration tests that check software behavior. Unit tests check small pieces of code, while integration tests check how parts work together.

In plain words
What is it for?
It covers normal, error, and edge cases; clear test structure and names; API and database boundaries; isolated test data; and testing every acceptance criterion.
Why use it?
It helps catch regressions and gives developers confidence to change code without breaking existing behavior.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/wojcikmm/spec-development-protocol/write-tests
Any agent
npx skills add WojcikMM/spec-development-protocol --skill write-tests
Clone the repo
git clone --depth 1 https://github.com/WojcikMM/spec-development-protocol

Made for: Claude Code, Codex.

Per session 13 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 313 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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 $0.00013 $0.00313
Opus 5 $0.00006 $0.00156
Sonnet 5 $0.00003 $0.00063
Haiku 4.5 $0.00001 $0.00031

Measured 2d ago against content hash 1246bcc42b57, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, 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 2d 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.

.apm/skills/write-tests/SKILL.md · 35 lines

What it actually says

Skill: Write Tests

Purpose

Produce maintainable tests that validate behavior, not implementation, to give the team confidence to ship and refactor.

Prerequisites

  • Acceptance criteria are clear.
  • Testing stack is specified in TECH.md.

Checklist

  1. Test Cases: Enumerate test cases from acceptance criteria: happy path, error paths, and edge cases.
  2. Structure (AAA): Structure each test using Arrange-Act-Assert.
    • Arrange: Set up inputs and mocks.
    • Act: Invoke the code under test.
    • Assert: Verify the outcome.
  3. Naming: Name tests descriptively, like should <do something> when <condition>.
  4. Focus: Focus on a single assertion per test where possible.
  5. Behavior, not Implementation: Test what the code does, not how it does it.
  6. Integration Tests: Test contracts at boundaries (HTTP, DB). Use real or in-memory implementations where practical. Cover auth paths. Reset state between tests.
  7. General: Don't skip failing tests—fix or delete them. Co-locate tests with source files.

Quality Bar

  • Every acceptance criterion is tested.
  • All scenarios (happy, error, edge) are covered.
  • Tests are isolated and deterministic (no network calls or global state).
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. 2d ago First seen · 35 lines · 13 tokens per session scan A 1246bcc42b57

Subscribe to this mod's changes

write-tests is a skill published in the GitHub repository WojcikMM/spec-development-protocol (2 stars, last pushed 22d ago), licensed MIT. It adds 13 tokens to every session and 313 once invoked, about $0.0001 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.