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 mikestangdevs/craft-skills --skill test-like-you-mean-itgit clone --depth 1 https://github.com/mikestangdevs/craft-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/mikestangdevs/craft-skills/test-like-you-mean-it)<a href="https://agentmods.dev/skills/mikestangdevs/craft-skills/test-like-you-mean-it"><img src="https://agentmods.dev/badge/skills/mikestangdevs/craft-skills/test-like-you-mean-it/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/mikestangdevs/craft-skills/test-like-you-mean-it"><img src="https://agentmods.dev/badge/skills/mikestangdevs/craft-skills/test-like-you-mean-it.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 | $0.00131 | $0.01251 |
| Opus 5 | $0.00066 | $0.00626 |
| Sonnet 5 | $0.00026 | $0.00250 |
| Haiku 4.5 | $0.00013 | $0.00125 |
Grade A, and why
test-like-you-mean-it 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 11d 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 — 77 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Test Like You Mean It
The failure mode this fixes
Agents write tests the way a student grades their own exam. They built the code, they want the code to work, so they write tests that confirm the happy path and assert whatever the code currently returns. The suite goes green, everyone relaxes — and nothing was actually verified. A test written to pass is worse than no test: it's a green light bolted over a blind corner.
The tell: tests that mirror the implementation ("returns X when given Y" where X was copied from the function's output), no test that could conceivably fail, no edge regimes, no invariants. Smoke tests presented as verification.
This skill replaces that with an adversarial wave: after the build, you switch sides. You are no longer the author defending the code — you are the reviewer trying to break it. Finding a real defect is the expected outcome, not an embarrassment.
When to Use This Skill
- A feature, calculation, model, or migration just landed and the next step would be "looks done"
- The only tests that exist were written in the same session as the code they test
- The suite passes but you couldn't say what property of the system it proves
- The domain has ground truth to check against — math identities, conservation laws, a reference implementation, a spec, known real-world values
- Someone (including you) is about to say "tests pass" as the reason to ship
Don't use when: the change is trivial plumbing with no behavior (a rename, a re-export), or you're in a genuine throwaway spike. Don't use it as a reason to write 100 shallow tests — ten tests that could fail beat a hundred that can't.
Instructions
1. Switch sides
Before writing a single test, write down (briefly) how this code could be wrong in ways the existing tests wouldn't catch. You're drafting an attack plan, not a checklist of what it does. If you can't name a way it could be wrong, you don't understand it yet — go read it again.
2. Test properties, not outputs
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.
- 11d ago First seen · 77 lines · 131 tokens per session scan A 8b14cbbcff23
test-like-you-mean-it is a skill published in the GitHub repository mikestangdevs/craft-skills (4 stars, last pushed 3mo ago), licensed MIT. It adds 131 tokens to every session and 1,251 once invoked, about $0.0007 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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refactoring-guru
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refactoring
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lab:autoresearch
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