plumb-testing

A testing workflow that identifies affected tests after code changes and runs the project's stored test task.

In plain words
What is it for?
Finding impacted tests and running test, build, lint, end-to-end, or verification tasks when available.
Why use it?
It reduces guesswork about which tests to run before declaring a change finished.

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/plumbkit/plumb/plumb-testing
Any agent
npx skills add plumbkit/plumb --skill plumb-testing
Clone the repo
git clone --depth 1 https://github.com/plumbkit/plumb

Made for: Claude Code, Codex.

Per session 40 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 1,064 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original 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 $0.00040 $0.01064
Opus 5 $0.00020 $0.00532
Sonnet 5 $0.00008 $0.00213
Haiku 4.5 $0.00004 $0.00106

Measured 2d ago against content hash 5756250ce530, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

plumb-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.

internal/cli/skills/plumb-testing/SKILL.md · 50 lines

How it starts

The opening of the file, as written. The whole thing — 50 lines — stays where its author put it; the contents beside it link to each section on GitHub.

After changing code in a codebase that has plumb available, verify the change before calling it done: ask which tests it touches, run those, and confirm the code still compiles — rather than guessing, or paying for the whole suite every time.

1. Ask which tests the change affects

topology_affected traverses inward dependency edges from what you changed and adds the tests co-located with the affected files:

topology_affected(files=["internal/tools/edit_file.go"])
topology_affected(symbols=["applyEdits"])

It is biased toward recall — a missed test is worse than an extra one — so every result carries a confidence and the reason it was flagged. Read those labels; they decide the last section.

2. Run what it named

run_task runs the project's stored [tasks.<lang>] command with no shell and bounded output:

run_task(slot="test")      # the stored test command, whole
run_task(slot="verify")    # build, then test

slot is build / lint / test / e2e / verify. target fills a {target} placeholder with one shell-safe argument, and the shipped go, python and rust test defaults now carry a defaulted one (go test {target:./...}, pytest {target:}, cargo test {target:}), so scoping works on an unmodified install and a bare run_task(slot="test") still runs everything. npm test, swift test and zig build test have no placeholder, because those runners scope through flags whose spelling depends on the project — a target passed to a command without a placeholder is refused.

When the command takes a positional path, topology_affected hands you the target already shaped for it, relative to [tasks.<lang>].working_dir, so the two compose directly:

run_task(slot="test", target="./internal/config/...")   # a row from topology_affected, verbatim

Where no target can be spelled — a runner that scopes by test name, a project-specific flag, or a package outside the command's working_dirtopology_affected names the directory and guesses no command. Use your own runner there, but keep the scope it gave you. When the project configures no command for the slot, use the client's runner too — but keep the scope topology_affected gave you. A project-supplied command that is not yet trusted is refused with a pointer to plumb trust: that is a gate, not a missing command — surface it rather than shelling around it.

Read the full file on GitHub · 50 lines

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 · 50 lines · 40 tokens per session scan A 5756250ce530

Subscribe to this mod's changes

plumb-testing is a skill published in the GitHub repository plumbkit/plumb (4 stars, last pushed 2d ago), licensed MIT. It adds 40 tokens to every session and 1,064 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.

Related

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