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 PaulRBerg/agent-skills --skill vitestgit clone --depth 1 https://github.com/PaulRBerg/agent-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/paulrberg/agent-skills/vitest)<a href="https://agentmods.dev/skills/paulrberg/agent-skills/vitest"><img src="https://agentmods.dev/badge/skills/paulrberg/agent-skills/vitest/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/paulrberg/agent-skills/vitest"><img src="https://agentmods.dev/badge/skills/paulrberg/agent-skills/vitest.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
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 | $0.00041 | $0.00423 |
| Opus 5.5 | $0.00016 | $0.00169 |
| Sonnet 5.5 | $0.00008 | $0.00085 |
| Haiku 4.5 | $0.00004 | $0.00042 |
Grade A, and why
vitest 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 1mo 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.
What it actually says
Vitest
Repository configuration, projects, setup, imports/globals, environments, aliases, test placement, and cleanup own the test contract. Inspect them and nearby tests before adding generic patterns. Do not add globals, jsdom, coverage, new setup, or browser mode by default.
Workflow
Define the behavior or regression. Test its observable public result. Mock system boundaries rather than the behavior
under test. Follow local fixture and cleanup ownership. In Effect repositories, use established @effect/vitest
conventions such as it.effect, Layers, and TestClock rather than generic replacements. For a bug fix, reproduce the
failure before relying on a passing result when practical.
Read patterns for component, async, fixture, snapshot, tag, or browser questions. Read mocking for module, timer, spy, or global boundaries. Read configuration for projects, migration, coverage, or reporter selection. Read troubleshooting for hangs, discovery, resolution, or flaky state.
For test changes, run the narrowest established command for the changed behavior, then the affected package suite only
when shared setup or contracts changed. Use nlx vitest run only when no project recipe or script exists. Reuse passing
results until new edits, failures, or unresolved concerns justify another run.
Completion requires a meaningful passing focused test under repository configuration and concise command/result evidence
for test changes. A read-only explanation instead requires supporting configuration or API evidence. Do not add or run
tests merely to satisfy the change workflow. When red-before-green evidence exists, use ### 🧪 Regression covered.
Otherwise, use ### 🧪 Tests verified for executed tests.
What ships with it
5 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.
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.
- 1mo ago Changed a5534d77e2a5
- 1mo ago Changed · +4 lines a50324a6075e
- 1mo ago Changed · -18 lines aa9acd73c49c
- 2mo ago First seen · 48 lines · 41 tokens per session scan A 50cd5eca47e5
vitest is a skill published in the GitHub repository PaulRBerg/agent-skills (104 stars, last pushed 2d ago), licensed MIT. It adds 41 tokens to every session and 423 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.
vitest compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| vitestPaulRBerg/agent-skills | Skill | 104 | 2d ago | MIT | A | 41 | Codex |
| vitest-skillLambdaTest/agent-skills | Skill | 391 | 3d ago | MIT | A | 76 | Claude Code, Codex |
| typescriptalinaqi/maggy | Skill | 711 | 26d ago | MIT | A | 10 | Claude Code |
| jest-unitPramodDutta/qaskills | Skill | 245 | 6d ago | MIT | A | 32 | Claude Code |
| Jasmine TestingPramodDutta/qaskills | Skill | 245 | 6d ago | MIT | A | 35 | Claude Code, Codex |
| typescript-testingshinpr/ai-coding-project-boilerplate | Skill | 236 | yesterday | MIT | A | 31 | Claude Code |
| jestMindrally/skills | Skill | 301 | 1mo ago | Apache-2.0 | A | 25 | Claude Code |