buffer-crc32 0.2.13

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 pkg:npm/buffer-crc32@0.2.13
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/buffer-crc32@0.2.13

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:fe06330ebbfa01910942f3327c14c5e2a2073de30a80600f48ba2e759f74d560","contract":["crc32 computes 4-byte CRC32 checksum buffer for string and buffer inputs","crc32.signed returns signed 32-bit integer checksum","crc32.unsigned returns unsigned 32-bit integer checksum","crc32 supports incremental chunked calculation with previous checksum buffer or number"],"goal":"verify pkg:npm/buffer-crc32@0.2.13","kind":"HOW","packages":["pkg:npm/buffer-crc32@0.2.13"],"schemaVersion":1},"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/buffer-crc32@0.2.13"],"schemaVersion":1,"subject":"pkg:npm/buffer-crc32@0.2.13","verifierAdapter":"node-typescript@1"}

import crc32 from 'buffer-crc32';

export function calculateCrc32(input) {
  return crc32(input);
}

export function calculateCrc32Signed(input) {
  return crc32.signed(input);
}

export function calculateCrc32Unsigned(input) {
  return crc32.unsigned(input);
}

export function calculateCrc32Incremental(chunks) {
  let prev = null;
  for (const chunk of chunks) {
    prev = prev === null ? crc32(chunk) : crc32(chunk, prev);
  }
  return prev;
}

{
  "name": "sample-buffer-crc32",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-buffer-crc32",
      "version": "1.0.0",
      "dependencies": {
        "buffer-crc32": "0.2.13"
      }
    },
    "node_modules/buffer-crc32": {
      "version": "0.2.13",
      "resolved": "https://registry.npmjs.org/buffer-crc32/-/buffer-crc32-0.2.13.tgz",
      "integrity": "sha512-VO9Ht/+p3SN7SKWqcrgEzjGbRSJYTx+Q1pTQC0wrWqHx0vpJraQ6GtHx8tvcg1rlK1byhU5gccxgOgj7B0TDkQ==",
      "license": "MIT",
      "engines": {
        "node": "*"
      }
    }
  }
}

{
  "name": "sample-buffer-crc32",
  "version": "1.0.0",
  "description": "Clean-room verification sample for buffer-crc32",
  "type": "module",
  "main": "index.mjs",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "buffer-crc32": "0.2.13"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/buffer-crc32@0.2.13",
  "kind": "HOW",
  "packages": [
    "pkg:npm/buffer-crc32@0.2.13"
  ]
}

import assert from 'node:assert/strict';
import crc32 from 'buffer-crc32';
import {
  calculateCrc32,
  calculateCrc32Signed,
  calculateCrc32Unsigned,
  calculateCrc32Incremental
} from '../index.mjs';

// Test basic CRC32 computation returning a Buffer
const bufResult = calculateCrc32('hello world');
assert(Buffer.isBuffer(bufResult), 'Expected result to be a Buffer');
assert.strictEqual(bufResult.length, 4, 'Expected 4-byte CRC32 Buffer');
assert.strictEqual(bufResult.toString('hex'), '0d4a1185', 'Expected hex match for hello world');

// Test direct call on Buffer input
const directBuf = crc32(Buffer.from('hello world'));
assert.strictEqual(directBuf.toString('hex'), '0d4a1185', 'Direct call matches');

// Test signed 32-bit integer output
const signedResult = calculateCrc32Signed('hello world');
assert.strictEqual(typeof signedResult, 'number', 'Expected signed result to be a number');
assert.strictEqual(signedResult, 222957957, 'Expected signed CRC32 value for hello world');
assert.strictEqual(crc32.signed('hello world'), 222957957, 'Direct signed match');

// Test unsigned 32-bit integer output
const unsignedResult = calculateCrc32Unsigned('hello world');
assert.strictEqual(typeof unsignedResult, 'number', 'Expected unsigned result to be a number');
assert.strictEqual(unsignedResult, 222957957, 'Expected unsigned CRC32 value for hello world');
assert.strictEqual(crc32.unsigned('hello world'), 222957957, 'Direct unsigned match');

// Test negative signed value / large unsigned value
const testBytes = Buffer.from([0xff, 0xff, 0xff, 0xff]);
const signedHigh = crc32.signed(testBytes);
const unsignedHigh = crc32.unsigned(testBytes);
assert.strictEqual(signedHigh, (unsignedHigh | 0), 'Signed and unsigned values relate via bitwise OR 0');

// Test incremental / chunked CRC32 calculation
const incrementalBuf = calculateCrc32Incremental(['hello ', 'world']);
assert.strictEqual(incrementalBuf.toString('hex'), '0d4a1185', 'Incremental calculation matches single-pass');

const chunk1 = crc32('hello ');
const chunk2 = crc32('world', chunk1);
assert.strictEqual(chunk2.toString('hex'), '0d4a1185', 'Manual chained crc32 matches');

console.log('All buffer-crc32 contract assertions passed.');