registry / gutcheck / 0.3.1

gutcheck@0.3.1

Prove your AI-written tests actually test your code: a diff-scoped mutation probe that guts each tested function and reruns only its test — plus a sub-second lint and a Claude Code Stop hook that re-probes what an agent just changed.

Static Scan Results

scanned 3h ago · by rust-scanner

Static analysis flagged 11 finding(s) at 72.0% confidence. This version is warn-only unless an AI or security-team review confirms malicious behavior.

Static reason

One or more suspicious static signals were detected.

Decision evidence

public snapshot

Behavioral surface

Source

ChildProcessCryptoEnvironmentVarsFilesystemShell

Supply chain

HighEntropyStringsUrlStrings

ManifestNo manifest risk signals triggered.

scanned 28 file(s), 484 KB of source, external domains: github.com, json.schemastore.org

Source & flagged code

4 flagged

mutation/probe.mjsView file

Lines 1-32javascript

1// mutation/probe.mjs — the minimal-decisive-probe: confirm a hollow/shadow test oracle by EXECUTION.

2//

3// A hollow test (a tautological / shadow oracle whose expected value re-runs or re-derives the code it

4// tests) is, by definition, one that SURVIVES a non-equivalent change to the code under test. This is

5// extreme mutation testing / "pseudo-tested method" detection (Niedermayr/Juergens/Wagner 2016;

6// Descartes/Vera-Pérez/Monperrus/Baudry 2018), scoped to ONE function feeding ONE flagged assertion:

7// gut that function with a gross, guaranteed-non-equivalent return and run ONLY the one test. If a

8// deliberately-broken SUT does not break the test, the oracle is HOLLOW.

9//

10// Pairs with the cheap static shadowOracleGuard, which is a high-recall CANDIDATE generator (it over-

11// flags — fixture-builders, formatters, equivalence tests). The probe is the precision gate: it clears

12// those false positives (a broken SUT makes a real test fail) and confirms the genuinely hollow ones.

13import { execSync } from 'node:child_process';

14import { mkdtempSync, cpSync, readFileSync, writeFileSync, rmSync, existsSync, symlinkSync } from 'node:fs';

High

Child Process

Package source references child process execution.

mutation/probe.mjsView on unpkg · L12

15import { tmpdir } from 'node:os';

16import { join } from 'node:path';

17import { codeOnly } from '../checker/lexer.mjs';

19// A mutation can induce an infinite loop (e.g. gutting a loop's termination condition), which without a

20// bound would hang the probe — and any CI / agent loop calling it — forever. Cap each test run; override

21// with GUTCHECK_PROBE_TIMEOUT_MS. A run that exceeds

22// it is treated as "not green" (the mutant is caught, or the unmutated test is too slow to probe →

23// INCONCLUSIVE at the baseline).

24const PROBE_TIMEOUT_MS = Number(process.env.GUTCHECK_PROBE_TIMEOUT_MS) || 60000;

26// Locate a named function's BODY and return a replacement descriptor, or null if it can't be located/

27// parsed (so the caller reports INCONCLUSIVE, never a wrong verdict). Handles `function NAME(` incl.

28// generators (`function* NAME` / `async function* NAME`), `def NAME(`, `NAME = function` / `NAME: function`

29// (a `=` binding or a `:` object property), parenthesised and bare single-param arrows (`NAME = x =>`),

30// block- and expression-bodied. All structural scanning is on a string/comment MASK (codeOnly blanks them

31// to spaces, positions preserved) so braces/parens/`=>` inside string literals or comments can't fool it,

32// and the parameter list is paren-balanced before the body is located so a default-param arrow

mutation/lock.mjsView file

Lines 3-42javascript

3// Stop hook firing mid-CLI-sweep). The second run must refuse with a stated reason, never collide.

4// The lockfile lives in the OS tmpdir keyed by the canonical repo path — never inside the repo (no

5// git-status pollution, no accidental commit). Stale = the owning pid is no longer alive; cleared

6// silently and retried once. A lock held by THIS process is re-entrant (main()'s full-suite fallback

7// re-runs prove(); an exception can leave a residue lock behind the same pid) — refusing ourselves

8// would deadlock the fallback for no safety gain.

9import { createHash } from 'node:crypto';

10import { writeFileSync, readFileSync, unlinkSync, realpathSync } from 'node:fs'

mutation/gate.mjsView file

Lines 1-32javascript

1// mutation/gate.mjs — the Stop-hook gate CORE, harness-agnostic. Ported verbatim from

2// hooks/check-changed-tests (now a thin `exec node ... gate --harness=<h>` caller) so more agent-loop

3// integrations can share the same probe-gate logic behind a small harness-adapter interface: one adapter

4// = how to read the world (parseEvent) + how to speak back (renderBlock/renderVoice/renderResidue).

5// Everything else below is shared, harness-agnostic gate logic.

6//

7// runGate() owns, in order: the harness event parse (fail-open on a malformed/unrecognized event), the

8// per-repo opt-outs (.gutcheck-off walked up-tree, GUTCHECK_HOOK=off), the git prerequisite (fail-open if

9// not a repo or git is missing), baseline resolution (<git-dir>/gutcheck-baseline, falling back to HEAD),

10// the diff-hash memo (read/write), loop-guard dispatch (one forced retry, then residue-only), the probe

mutation/py_blocks.pyView file

•path = mutation/py_blocks.py kind = build_helper sizeBytes = 21226 magicHex = [redacted]

Medium

Ships Build Helper

Package ships non-JavaScript build or shell helper files.

mutation/py_blocks.pyView on unpkg

Source & flagged code

4 flagged · loading source

mutation/probe.mjsView file

12// those false positives (a broken SUT makes a real test fail) and confirms the genuinely hollow ones. L13: import { execSync } from 'node:child_process'; L14: import { mkdtempSync, cpSync, readFileSync, writeFileSync, rmSync, existsSync, symlinkSync } from 'node:fs';

High

Child Process

Package source references child process execution.

mutation/probe.mjsView on unpkg · L12

mutation/lock.mjsView file

23const path = lockPathFor(dir); L24: const handle = { path, release() { try { if (JSON.parse(readFileSync(path, 'utf8')).pid === process.pid) unlinkSync(path); } catch {} } }; L25: for (let attempt = 0; attempt < 2; attempt++) {

Low

Weak Crypto

Package source references weak cryptographic algorithms.

mutation/lock.mjsView on unpkg · L23

mutation/gate.mjsView file

12Cross-file remote execution chain: mutation/gate.mjs spawns mutation/gutcheck.mjs; helper contains network access plus dynamic code execution. L12: // hook built). Every error path fails OPEN: null means "print nothing", same as the bash hook's exit 0. L13: import { execFileSync } from 'node:child_process'; L14: import { existsSync, readFileSync, writeFileSync, statSync, realpathSync } from 'node:fs'; ... L29: try { L30: const parsed = JSON.parse(stdinText); L31: return { gate: true, loopActive: !!parsed && parsed.stop_hook_active === true }; ... L326: L327: // runGate({ harnessName, dir, stdinText, env }) -> string|null (the stdout payload, null = silence) L328: export function runGate({ harnessName, dir, stdinText, env = {} }) {

High

Cross File Remote Execution Context

Source spawns a local helper that also contains network and dynamic execution context; review data flow before blocking.

mutation/gate.mjsView on unpkg · L12

mutation/py_blocks.pyView file

•path = mutation/py_blocks.py kind = build_helper sizeBytes = 21226 magicHex = [redacted]

Medium

Ships Build Helper

Package ships non-JavaScript build or shell helper files.

mutation/py_blocks.pyView on unpkg

Findings

3 High3 Medium5 Low

HighChild Processmutation/probe.mjs

HighShell

HighCross File Remote Execution Contextmutation/gate.mjs

MediumEnvironment Vars

MediumShips Build Helpermutation/py_blocks.py

MediumStructural Risk Force Deep Review

LowScripts Present

LowWeak Cryptomutation/lock.mjs

LowFilesystem

LowHigh Entropy Strings

LowUrl Strings