Borrowing it
Nothing to install: this file belongs to r3bl-org/r3bl-open-core. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/r3bl-org/r3bl-open-core/main/.agents/skills/check-test-coverage/SKILL.mdgit clone --depth 1 https://github.com/r3bl-org/r3bl-open-coreWrote 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/r3bl-org/r3bl-open-core/check-test-coverage)<a href="https://agentmods.dev/skills/r3bl-org/r3bl-open-core/check-test-coverage"><img src="https://agentmods.dev/badge/skills/r3bl-org/r3bl-open-core/check-test-coverage/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/r3bl-org/r3bl-open-core/check-test-coverage"><img src="https://agentmods.dev/badge/skills/r3bl-org/r3bl-open-core/check-test-coverage.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 | $0.00063 | $0.02333 |
| Opus 5.5 | $0.00025 | $0.00933 |
| Sonnet 5.5 | $0.00013 | $0.00467 |
| Haiku 4.5 | $0.00006 | $0.00233 |
Grade A, and why
check-test-coverage 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 — 205 lines — stays where its author put it; the contents beside it link to each section on GitHub.
// Copyright (c) 2026 R3BL LLC. Licensed under Apache License, Version 2.0.
Skill: check-test-coverage
Audit and verify test coverage for a specific file or module. Ensure all custom logic branches, state transitions, and boundary conditions are covered while strictly eliminating dependency test bloat (never testing std, third-party crates, or macro-derived boilerplate).
When to Use
- When invoked via the
/check-test-coverage <file_path>command. - When reviewing a file before creating a commit or finalizing a task.
- When evaluating whether a newly added or modified file has sufficient test coverage.
- When auditing existing test suites to identify missing custom logic tests or remove redundant test bloat.
Core Philosophy: Zero Test Bloat ("Test OUR Code, Not Dependencies")
Traditional "code coverage" tools blindly count lines or instructions executed, encouraging developers to write low-signal tests for boilerplate, compiler derives, and third-party crates.
In this codebase, test quality is measured by branch-targeted verification of OUR custom logic:
- Test OUR Code Exclusively:
- Tests must target the unique execution paths, custom algorithms, match branches, state transitions, conversion traits (
From,TryFrom), and error conditions written by us.
- Tests must target the unique execution paths, custom algorithms, match branches, state transitions, conversion traits (
- Never Test Dependencies or Compiler Derives:
- Never write tests that merely assert standard library behavior (
std::collections::HashMap,std::env,std::ffi::OsString). - Never write unit tests for standard compiler derives (
#[derive(Default, Clone, Copy, PartialEq, Eq, Debug)]). - Never write unit tests for third-party derive macros (such as
#[derive(Display, EnumString)]with#[strum(serialize_all = "lowercase")]orclap::ValueEnum).
- Never write tests that merely assert standard library behavior (
- High Signal, Low Maintenance Overhead:
- Redundant tests slow down
cargo testandcheck.fishiteration cycles. - Redundant test failures during refactoring obscure real bugs and create maintenance friction.
- Redundant tests slow down
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.
- 11d ago Changed a2efc035890f
- 15d ago Changed · +58 lines febafcee444e
- 1mo ago First seen · 147 lines · 63 tokens per session scan A 7f35e5e00269
check-test-coverage is a skill published in the GitHub repository r3bl-org/r3bl-open-core (486 stars, last pushed yesterday), licensed Apache-2.0. It adds 63 tokens to every session and 2,333 once invoked, about $0.0003 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 2026-09-06.
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