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/nickpolyder/np.copilot.config/test-gap-fillnpx skills add NickPolyder/NP.CoPilot.Config --skill test-gap-fillgit clone --depth 1 https://github.com/NickPolyder/NP.CoPilot.ConfigWrote 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/nickpolyder/np.copilot.config/test-gap-fill)<a href="https://agentmods.dev/skills/nickpolyder/np.copilot.config/test-gap-fill"><img src="https://agentmods.dev/badge/skills/nickpolyder/np.copilot.config/test-gap-fill.svg" alt="Measured on agentmods" 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 | $0.00036 | $0.01190 |
| Opus 5 | $0.00018 | $0.00595 |
| Sonnet 5 | $0.00007 | $0.00238 |
| Haiku 4.5 | $0.00004 | $0.00119 |
Grade A, and why
test-gap-fill 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 4d 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 — 120 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Purpose
Intent (anchor): Generate concrete, runnable tests for approved coverage gaps and report any real bugs the new tests expose. Always: require explicit approval of which gaps to fill; follow existing test conventions; run generated tests and report results. Never: modify production code without asking, generate tests for trivial code, or invent conventions that conflict with the project.
Shared policy: Follow
instructions/coordination.instructions.mdfor precedence, invocation, delegation, and handoffs. Applyinstructions/workflow.instructions.mdfor proportional work and verification.
You are filling approved test gaps with concrete, runnable tests.
Your goals are to:
- Confirm approval — generate only the gaps the user explicitly approved.
- Generate tests — add or improve tests that follow the project's framework, naming, fixtures, and assertion style.
- Verify behavior — run the generated tests and report pass/fail results.
- Surface bugs — clearly identify any real bug exposed by a generated test before touching production code.
When to use this skill
Use this skill whenever:
test-gap-audithas produced a gap report and the user approved specific gaps to fill.- The user provides an explicit list of existing coverage gaps and asks for tests to be generated.
- A production incident has an approved "what test would have caught this?" follow-up.
- You are continuing the chain:
test-gap-audit→ approval →test-gap-fill.
Do not use this skill for:
- Read-only coverage discovery — use
test-gap-audit. - Planning tests for new features — use
test-strategyinstead. - Refactoring production code or test architecture before test generation — recommend
refactorif structural cleanup is needed. - Code review — use
git-commit-revieworcode-revieweragent.
Workflow
Phase 1: Approval Gate
Approval gate: stop until the user explicitly approves which tests to generate (all critical, critical + high, selected items, or report only).
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.
- 4d ago First seen · 120 lines · 36 tokens per session scan A 41daeaa6cfef
test-gap-fill is a skill published in the GitHub repository NickPolyder/NP.CoPilot.Config (2 stars, last pushed 10d ago), licensed MIT. It adds 36 tokens to every session and 1,190 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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