pvutils 1.2.0: utilConcatBuf

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 pvutils.utilConcatBuf in pkg:npm/pvutils@1.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/pvutils@1.2.0
Demonstrate these symbols/APIs:
  - pvutils.utilConcatBuf

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.

{"case":{"caseId":"case:sha256:c7edd3aefd5c095c454b060e29c5d0805fc4c8a2cc31f63c306e6da6b6f53e80","contract":["utilConcatBuf concatenates multiple ArrayBuffer instances into a single contiguous ArrayBuffer","utilConcatBuf preserves byte ordering and element values across joined buffers","utilConcatBuf returns an empty ArrayBuffer when invoked with zero arguments or empty buffers","utilConcatBuf returns an equivalent ArrayBuffer when given a single buffer argument"],"goal":"verify pvutils.utilConcatBuf in pkg:npm/pvutils@1.2.0","kind":"HOW","packages":["pkg:npm/pvutils@1.2.0"],"schemaVersion":1,"symbols":["pvutils.utilConcatBuf"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/pvutils@1.2.0"],"schemaVersion":1,"subject":"pkg:npm/pvutils@1.2.0","symbols":["pvutils.utilConcatBuf"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-pvutils",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-pvutils",
      "version": "1.0.0",
      "dependencies": {
        "pvutils": "1.2.0"
      }
    },
    "node_modules/pvutils": {
      "version": "1.2.0",
      "resolved": "https://registry.npmjs.org/pvutils/-/pvutils-1.2.0.tgz",
      "integrity": "sha512-BbubeCEyTuQjVMakvJQ/Sxbc93F2pwmbsxONT/ZRrwU7Ua38d8unYTwXpTVLAKJ4BDuH9IGztCjQcd/N/39Dvg==",
      "license": "MIT",
      "engines": {
        "node": ">=16.0.0"
      }
    }
  }
}

{
  "name": "sample-pvutils",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification of pvutils.utilConcatBuf",
  "type": "module",
  "main": "src/index.js",
  "dependencies": {
    "pvutils": "1.2.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pvutils.utilConcatBuf in pkg:npm/pvutils@1.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/pvutils@1.2.0"
  ],
  "symbols": [
    "pvutils.utilConcatBuf"
  ]
}

import { utilConcatBuf } from 'pvutils';

/**
 * Concatenate multiple ArrayBuffers into a single contiguous ArrayBuffer.
 * @param {...ArrayBuffer} buffers
 * @returns {ArrayBuffer}
 */
export function concatBuffers(...buffers) {
  return utilConcatBuf(...buffers);
}

export { utilConcatBuf };

import assert from 'node:assert';
import { utilConcatBuf, concatBuffers } from '../src/index.js';

// 1. utilConcatBuf concatenates multiple ArrayBuffer instances into a single contiguous ArrayBuffer
{
  const buf1 = new Uint8Array([1, 2, 3]).buffer;
  const buf2 = new Uint8Array([4, 5]).buffer;
  const buf3 = new Uint8Array([6, 7, 8, 9]).buffer;
  const result = utilConcatBuf(buf1, buf2, buf3);

  assert.strictEqual(result instanceof ArrayBuffer, true);
  assert.strictEqual(result.byteLength, 9);
  assert.deepStrictEqual(Array.from(new Uint8Array(result)), [1, 2, 3, 4, 5, 6, 7, 8, 9]);
}

// 2. utilConcatBuf preserves byte ordering and element values across joined buffers
{
  const first = new Uint8Array([0xaa, 0xbb]).buffer;
  const second = new Uint8Array([0xcc, 0xdd, 0xee]).buffer;
  const merged = concatBuffers(first, second);

  assert.strictEqual(merged.byteLength, 5);
  const view = new Uint8Array(merged);
  assert.strictEqual(view[0], 0xaa);
  assert.strictEqual(view[1], 0xbb);
  assert.strictEqual(view[2], 0xcc);
  assert.strictEqual(view[3], 0xdd);
  assert.strictEqual(view[4], 0xee);
}

// 3. utilConcatBuf returns an empty ArrayBuffer when invoked with zero arguments or empty buffers
{
  const noArgs = utilConcatBuf();
  assert.strictEqual(noArgs instanceof ArrayBuffer, true);
  assert.strictEqual(noArgs.byteLength, 0);

  const emptyA = new ArrayBuffer(0);
  const emptyB = new ArrayBuffer(0);
  const emptyMerged = utilConcatBuf(emptyA, emptyB);
  assert.strictEqual(emptyMerged instanceof ArrayBuffer, true);
  assert.strictEqual(emptyMerged.byteLength, 0);
}

// 4. utilConcatBuf returns an equivalent ArrayBuffer when given a single buffer argument
{
  const single = new Uint8Array([42, 43, 44]).buffer;
  const result = utilConcatBuf(single);

  assert.strictEqual(result instanceof ArrayBuffer, true);
  assert.strictEqual(result.byteLength, 3);
  assert.deepStrictEqual(Array.from(new Uint8Array(result)), [42, 43, 44]);
}

console.log('All pvutils.utilConcatBuf contract assertions passed.');