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Sample

jest-util 30.4.1: isNonNullable

Verified sample for npm jest-util 30.4.1: isNonNullable. The contract ran on node 22 · linux debian/x64 · docker and passed: isNonNullable returns false for…

sha256:68000f962eaca2b3c8943620796cf73c8c12474c1b8157693d649aa1bfd7ea41

This network offers one thing: a sample that builds. It ran the sample in a sandbox and kept the signed receipt. It grades nothing and warrants nothing — whether the same code builds where you are is not something it measured. How many distinct signing keys filed a passing contract receipt. One is the author alone; more than one means somebody else built it too. A key is self-generated with nothing registered behind it, so it counts keys, not people. MIT-0

Execution evidence

The declared environment and the signed runs are kept apart, so you can see exactly what this sample ran and where.

Evidence basis
Signed contract pass
Verification receipts
1
Signing keys that built it
1
Declared environment node 22.23 linux 24 · ubuntu · glibc 2.39 x64 node 22.23 javascript npm 10

Verification-run environments

Environment Contract Stages Run
node 22 · linux debian/x64 · docker ed25519:c1973797be207ac4 PASS compile:SKIPPED · contract:PASS · load:PASS · resolve:PASS
CONTAINER_RUN · node-typescript@1node:22@sha256:8a34c4ab3ea2…		 2026-09-06

Case

HOW
Goal
verify jest-util.isNonNullable in pkg:npm/jest-util@30.4.1
Packages
Symbols
  • jest-util.isNonNullable
Environment
node 22.23.2
Created
2026-09-06T08:01:05Z

Contract

  1. isNonNullable returns false for null and undefined
  2. isNonNullable returns true for boolean values including false and true
  3. isNonNullable returns true for numeric values including zero and NaN
  4. isNonNullable returns true for string values including empty strings
  5. isNonNullable returns true for objects, arrays, and symbols
  6. isNonNullable acts as a predicate function in Array.prototype.filter to filter out null and undefined values

Files

  • PROMPT.md
  • csx.json
  • index.js
  • package-lock.json
  • package.json
  • spec.json
  • test/contract.mjs

Download the source artifact (tar.gz)

Source

PROMPT.md
Clean-room public code sample — generation instructions

Write a brand-new, minimal, self-contained code sample in this clean-room directory.
Do not copy, paraphrase, or reference any existing project source. Work only from this spec.

A csx.json manifest scaffold already exists. Do not recreate it from memory. Preserve its case.goal, packages and symbols; fill its empty case.contract with exact assertions and correct its environment, commands and verifierAdapter for the files you generate.

Goal: verify jest-util.isNonNullable in pkg:npm/jest-util@30.4.1
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/jest-util@30.4.1
Demonstrate these symbols/APIs:
  - jest-util.isNonNullable

Rules:
  - One focused purpose; the smallest project that proves the goal.
  - Include a contract test (test/contract.*) that runs OFFLINE and exits 0 exactly when the goal behavior works.
  - Pin every dependency with a lockfile so resolution is reproducible.
  - No secrets, credentials, or tokens. No real URLs (only example.com or localhost). No absolute paths.
  - No personal names, emails, company names, or project identifiers of any kind.
  - No binaries and no generated output (node_modules, dist, target, venv, .git, .env).
  - Keep it under 200 files and 256KB packed.
csx.json
{"case":{"caseId":"case:sha256:ad25f1df3a482e5215b25d31874e0cbfb21dedb44b3db6e3298403ea6089b228","constraints":{"executionContext":"node"},"contract":["isNonNullable returns false for null and undefined","isNonNullable returns true for boolean values including false and true","isNonNullable returns true for numeric values including zero and NaN","isNonNullable returns true for string values including empty strings","isNonNullable returns true for objects, arrays, and symbols","isNonNullable acts as a predicate function in Array.prototype.filter to filter out null and undefined values"],"goal":"verify jest-util.isNonNullable in pkg:npm/jest-util@30.4.1","kind":"HOW","packages":["pkg:npm/jest-util@30.4.1"],"schemaVersion":1,"symbols":["jest-util.isNonNullable"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","packageManagerVersion":"10.9.8","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/jest-util@30.4.1"],"schemaVersion":1,"subject":"pkg:npm/jest-util@30.4.1","symbols":["jest-util.isNonNullable"],"verifierAdapter":"node-typescript@1"}
index.js
'use strict';

const jestUtil = require('jest-util');
const isNonNullable = jestUtil.isNonNullable;

/**
 * Checks if a value is neither null nor undefined.
 * @template T
 * @param {T} value
 * @returns {boolean}
 */
function checkNonNullable(value) {
  return isNonNullable(value);
}

/**
 * Filters an array removing all null and undefined elements.
 * @template T
 * @param {Array<T>} array
 * @returns {Array<NonNullable<T>>}
 */
function filterNonNullable(array) {
  return array.filter(isNonNullable);
}

module.exports = {
  isNonNullable,
  checkNonNullable,
  filterNonNullable,
};
package-lock.json
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package.json
{
  "name": "sample-jest-util-is-non-nullable",
  "version": "1.0.0",
  "description": "Minimal clean-room sample verifying isNonNullable in jest-util",
  "main": "index.js",
  "license": "MIT-0",
  "dependencies": {
    "jest-util": "30.4.1"
  }
}
spec.json
{
  "schemaVersion": 1,
  "goal": "verify jest-util.isNonNullable in pkg:npm/jest-util@30.4.1",
  "kind": "HOW",
  "packages": [
    "pkg:npm/jest-util@30.4.1"
  ],
  "symbols": [
    "jest-util.isNonNullable"
  ]
}
test/contract.mjs
import assert from 'node:assert/strict';
import { isNonNullable } from 'jest-util';
import { checkNonNullable, filterNonNullable } from '../index.js';

// 1. isNonNullable returns false for null and undefined
assert.equal(isNonNullable(null), false, 'isNonNullable(null) must be false');
assert.equal(checkNonNullable(null), false, 'checkNonNullable(null) must be false');
assert.equal(isNonNullable(undefined), false, 'isNonNullable(undefined) must be false');
assert.equal(checkNonNullable(undefined), false, 'checkNonNullable(undefined) must be false');

// 2. isNonNullable returns true for boolean values including false and true
assert.equal(isNonNullable(false), true, 'isNonNullable(false) must be true');
assert.equal(isNonNullable(true), true, 'isNonNullable(true) must be true');
assert.equal(checkNonNullable(false), true, 'checkNonNullable(false) must be true');
assert.equal(checkNonNullable(true), true, 'checkNonNullable(true) must be true');

// 3. isNonNullable returns true for numeric values including zero and NaN
assert.equal(isNonNullable(0), true, 'isNonNullable(0) must be true');
assert.equal(isNonNullable(-0), true, 'isNonNullable(-0) must be true');
assert.equal(isNonNullable(42), true, 'isNonNullable(42) must be true');
assert.equal(isNonNullable(NaN), true, 'isNonNullable(NaN) must be true');
assert.equal(isNonNullable(Infinity), true, 'isNonNullable(Infinity) must be true');

// 4. isNonNullable returns true for string values including empty strings
assert.equal(isNonNullable(''), true, 'isNonNullable("") must be true');
assert.equal(isNonNullable('hello'), true, 'isNonNullable("hello") must be true');
assert.equal(checkNonNullable(''), true, 'checkNonNullable("") must be true');

// 5. isNonNullable returns true for objects, arrays, and symbols
assert.equal(isNonNullable({}), true, 'isNonNullable({}) must be true');
assert.equal(isNonNullable([]), true, 'isNonNullable([]) must be true');
assert.equal(isNonNullable(Symbol('sample')), true, 'isNonNullable(Symbol) must be true');
assert.equal(isNonNullable(BigInt(0)), true, 'isNonNullable(0n) must be true');

// 6. isNonNullable acts as a predicate function in Array.prototype.filter to filter out null and undefined values
const raw = [0, null, 'a', undefined, false, '', null, NaN];
const filtered = raw.filter(isNonNullable);
assert.deepEqual(filtered, [0, 'a', false, '', NaN], 'filter must keep falsy non-nullable values and remove null/undefined');
const helperFiltered = filterNonNullable(raw);
assert.deepEqual(helperFiltered, [0, 'a', false, '', NaN], 'helper function filterNonNullable must match filter behavior');

console.log('Contract tests passed successfully.');

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