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 agentmods add skills/localplugins/plugins/test-qualitynpx skills add localplugins/plugins --skill test-qualitygit clone --depth 1 https://github.com/localplugins/pluginsWhat 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 | $0.00030 | $0.00434 |
| Opus 5 | $0.00015 | $0.00217 |
| Sonnet 5 | $0.00006 | $0.00087 |
| Haiku 4.5 | $0.00003 | $0.00043 |
Grade A, and why
test-quality 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 yesterday.
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.
What it actually says
Test Quality
A good test catches a real regression and reads as a spec of intended behavior. A test that can't fail when the code breaks is worse than no test — it gives false confidence.
Use when
- Writing or updating a test (as
test-writer). - Judging whether a test is worth keeping (as
green-guardian).
Decision guide
- Assert behavior, not implementation. Check outputs and observable effects, so refactors don't break the test but bugs do.
- Critical path first, then real edge cases — empty/null inputs, boundaries, error paths, off-by-one. Skip edge cases that can't actually occur.
- Narrowest assertion that captures intent — exact values over "truthy".
- Deterministic — no reliance on time, network, ordering, or randomness without control.
- Named for the behavior —
returns_zero_for_empty_cart, nottest1. - One behavior per test — split so a failure localizes the bug.
- Match the project — its framework, file layout, and naming conventions. Put the test where its neighbors live.
Avoid
- Tautologies (
expect(x).toBe(x)) and mock-testing-mocks (asserting only that a mock was called, with no real output check). - Over-mocking that hides the behavior under test.
- One giant test asserting ten things.
- Snapshot tests as a substitute for meaningful assertions.
Every test you write should pass its revert-verification (see the anti-fake-green skill): fail on the pre-change code, pass on the change.
Deep reference
references/test-patterns.md— good-vs-bad test examples across ecosystems: behavioral vs. implementation assertions, edge-case selection, controlling nondeterminism, right-sized mocking, and one-behavior-per-test splits.
What ships with it
1 file beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- yesterday First seen · 37 lines · 30 tokens per session scan A 9cdd17f32522
test-quality is a skill published in the GitHub repository localplugins/plugins (5 stars, last pushed 1mo ago), licensed MIT. It adds 30 tokens to every session and 434 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 2026-08-31.
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