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.
npx skills add niels-emmer/myace --skill test-patternsgit clone --depth 1 https://github.com/niels-emmer/myaceWrote 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.
[](https://agentmods.dev/skills/niels-emmer/myace/test-patterns)<a href="https://agentmods.dev/skills/niels-emmer/myace/test-patterns"><img src="https://agentmods.dev/badge/skills/niels-emmer/myace/test-patterns/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.
<a href="https://agentmods.dev/skills/niels-emmer/myace/test-patterns"><img src="https://agentmods.dev/badge/skills/niels-emmer/myace/test-patterns.svg" alt="Reviewed on agentmods" width="80" height="20"></a>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 | $0.00028 | $0.00633 |
| Opus 5 | $0.00014 | $0.00316 |
| Sonnet 5 | $0.00006 | $0.00127 |
| Haiku 4.5 | $0.00003 | $0.00063 |
Grade A, and why
Test Patterns 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 8d 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.
How it starts
The opening of the file, as written. The whole thing — 30 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Purpose
A test suite that only exercises the happy path proves the code works when everything goes right, which is the case least likely to break in production. The failure modes — bad input, empty state, concurrent access, partial success — are where real bugs live and where a thin test suite gives false confidence. This skill is a checklist for deliberately covering that space instead of stopping at the first green run.
When to use it
Any time you write or extend tests for a nontrivial change — new functionality, a bug fix, or a refactor of logic that has any conditional branching. Run through the checklist below as a deliberate step, not an afterthought after the happy-path test already passes.
Checklist
- Happy path — the code does the intended thing with valid, typical input. Necessary but not sufficient; don't stop here.
- Boundary values — empty string/list/collection, zero, negative numbers where they're conceptually possible, the first and last valid index, one-past-the-boundary values that should be rejected.
- Null/missing/malformed input —
None/null/undefinedwhere a value is expected, a required field missing from a payload, a type that doesn't match what's expected, malformed JSON or encoding. - Failure and partial-failure modes — what happens when a dependency (network call, database, filesystem) fails outright, times out, or returns a partial/unexpected result. A test that only mocks the success response isn't testing the failure path at all.
- Concurrency and ordering, where relevant — two callers hitting the same code path at once, operations that assume an order that isn't actually guaranteed, idempotency (does calling this twice with the same input cause a problem it shouldn't).
- Regression coverage for bug fixes — a fix without a test that fails on the old code and passes on the new one isn't confirmed to have actually fixed anything; it's confirmed to compile.
- Authorization boundaries, where applicable — does a test confirm that a user without permission is actually denied, not just that a user with permission is allowed. A missing negative-authorization test is a common way authz bugs slip through.
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.
- 8d ago First seen · 30 lines · 28 tokens per session scan A 8989cd036ceb
Test Patterns is a skill published in the GitHub repository niels-emmer/myace (1 stars, last pushed 5d ago), licensed MIT. It adds 28 tokens to every session and 633 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 2026-09-03.
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