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 iliaal/ai-skills --skill writing-testsgit clone --depth 1 https://github.com/iliaal/ai-skillsWrote 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/iliaal/ai-skills/writing-tests)<a href="https://agentmods.dev/skills/iliaal/ai-skills/writing-tests"><img src="https://agentmods.dev/badge/skills/iliaal/ai-skills/writing-tests/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/iliaal/ai-skills/writing-tests"><img src="https://agentmods.dev/badge/skills/iliaal/ai-skills/writing-tests.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector warn
SkillSpector: 1 finding, up to high
These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →
- high Memory Poisoning · line 187 Skill manipulates agent memory, state, or stored context. Memory corruption can alter personality, override safety rules, or cause unpredictable behavior.Fix: Protect agent memory and state from modification by untrusted content. Use read-only memory for critical instructions and validate all state changes.
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 | $0.00048 | $0.01043 |
| Opus 5.5 | $0.00019 | $0.00417 |
| Sonnet 5.5 | $0.00010 | $0.00209 |
| Haiku 4.5 | $0.00005 | $0.00104 |
Grade A, and why
writing-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 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 — 41 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Writing tests
Produce tests that prove the requested behavior and fail when that behavior breaks. Follow user scope and the repository's actual contracts; this skill does not authorize implementation, external actions, or changes to acceptance criteria.
Procedure
- Discover the repository's runner, pinned wrapper, configuration, neighboring tests, and CI command before writing tests. Learn both focused and full-suite commands. Use project tooling rather than a global default; keep tracked scripts portable and apply personal wrappers only to the outer invocation.
- Derive cases from user requirements, implemented behavior, and claims intended for the handoff. Map each acceptance criterion to a discriminating case that a plausible wrong implementation fails. Name tests by observable behavior; keep one behavior per test and make fixtures adversarial on the axis under test.
- For bug fixes with a reachable test seam, write the reproducer, observe the intended failure, apply the smallest fix, and observe green. If the actual trigger cannot be reached, follow the missing-seam rules in test-completion.md. For new features, follow the selected test posture in vertical slices: default to tests-after (one small implementation slice, then its test); with an explicit test-first choice, write one test, then the minimal implementation that passes it. Repeat by slice; writing all tests first and all implementation afterward (horizontal slicing) is an anti-pattern that produces tests for imagined behavior. Refactor after green. Never alter a specification, assertion, fixture, snapshot, or expected output merely to make the implementation pass.
- Prefer real internal objects, real temporary files, and real test databases. Mock only external boundaries, at the last owned adapter; framework-maintained fakes are appropriate where the framework recommends them. Check the real contract and side effects before mocking.
- Assert consumer-visible outcomes rather than private structure, mock calls, or framework behavior. Include relevant boundary, invalid-input, concurrency, and failure cases. If error handling catches, logs, substitutes, or rolls back, assert its observable result as well as error visibility.
- Prove absence/isolation assertions with a run-unique forbidden violation and observe that specific assertion fail. Confirm the control mutation actually landed and its build completed before evaluating it. Remove the control, restore the artifact, and verify green.
- Run the narrow checks during edits and the applicable complete checks before handoff. Inspect passed/executed counts; an empty or skipped suite is not positive evidence.
What ships with it
11 files 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.
- references/anti-patterns-extended.md 3.0 KB
- references/false-pass-oracle-traps.md 8.6 KB
- references/generated-corpus-techniques.md 2.4 KB
- references/isolation-and-sandbox-traps.md 5.6 KB
- references/oracle-smells.md 9.8 KB
- references/rationalization-table.md 2.0 KB
- references/regression-proof.md 3.0 KB
- references/test-completion.md 3.7 KB
- references/test-design.md 12 KB
- references/test-smells.md 7.8 KB
- SPEC.md 4.4 KB
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 Changed d6b1262c78a5
- 24d ago Changed 25b33ea06335
- 1mo ago Changed 29e5459cd7c0
- 1mo ago Changed 24f4126c8d68
- 1mo ago Changed · -277 lines 5f4450cb9fd5
- 1mo ago Changed · +11 lines 1759c7d9f0ef
- 1mo ago First seen · 307 lines · 48 tokens per session scan A 7637a83e34a0
writing-tests is a skill published in the GitHub repository iliaal/ai-skills (45 stars, last pushed 3d ago), licensed MIT. It adds 48 tokens to every session and 1,043 once invoked, about $0.0002 per session on Opus 5.5. 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 2026-08-30.
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