c-testing

A workflow for testing C code, covering both unit tests for small parts and integration tests for parts working together. It includes CMake and CTest, tools that build and run test suites, plus checks for memory errors and undefined behaviour.

In plain words
What is it for?
Use it to write or repair tests for C11 or newer modules, stabilize unreliable test suites, and reproduce memory-safety or undefined-behaviour bugs.
Why use it?
It provides a consistent way to run tests and investigate crashes, flaky tests, memory bugs, and invalid C operations. Fuzzing can be added when ordinary tests do not find the problem.

Skill for Claude CodeCodex

Install

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.

agentmods
npx agentmods add skills/aeondave/malskill/c-testing
Any agent
npx skills add AeonDave/malskill --skill c-testing
Clone the repo
git clone --depth 1 https://github.com/AeonDave/malskill

Made for: Claude Code, Codex.

Per session 59 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 801 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin unknown No closer match found in the catalogue.
Token cost

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.

ModelPer sessionOnce invoked
Fable 5 $0.00059 $0.00801
Opus 5 $0.00030 $0.00400
Sonnet 5 $0.00012 $0.00160
Haiku 4.5 $0.00006 $0.00080

Measured 2d ago against content hash b251149ab5e1, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

c-testing 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 2d 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.

coding/c-testing/SKILL.md · 88 lines

The source is not reproduced here

No licence file

A repository with no LICENSE is all rights reserved by default, so the body is not copied here. The metadata, the measurements and the link are.

Read it on GitHub

Files

What ships with it

4 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.

Changes

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.

  1. 2d ago First seen · 88 lines · 59 tokens per session scan A b251149ab5e1

Subscribe to this mod's changes

c-testing is a skill published in the GitHub repository AeonDave/malskill (18 stars, last pushed 5d ago), with no licence file. It adds 59 tokens to every session and 801 once invoked, about $0.0003 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 2026-08-30.

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