chromium-pickle-js 0.2.0: createEmpty, createFromBuffer

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/chromium-pickle-js@0.2.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/chromium-pickle-js@0.2.0
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - runtime: node@22.23.2

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:sha256:2a8593e5836b43efa8f92fa1b859ef2940f790b35ad5147c877cd3218bee6c31","constraints":{"executionContext":"node"},"contract":["createEmpty returns a new Pickle instance that can write bool, int, uint32, float, double, and string primitives","Pickle.toBuffer returns a Buffer containing the 4-byte payload size header followed by 4-byte aligned payload data","createFromBuffer initializes a Pickle instance from an existing Buffer for reading with PickleIterator","PickleIterator sequentially reads bool, int, uint32, float, double, and string values in matching write order","Pickle.writeInt64 and Pickle.writeUInt64 throw TypeError in Node.js because 64-bit buffer write methods are undefined on Buffer.prototype","PickleIterator throws an Error when attempting to read past the payload buffer end"],"goal":"verify pkg:npm/chromium-pickle-js@0.2.0","kind":"HOW","packages":["pkg:npm/chromium-pickle-js@0.2.0"],"schemaVersion":1,"symbols":["createEmpty","createFromBuffer"]},"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/chromium-pickle-js@0.2.0"],"schemaVersion":1,"subject":"pkg:npm/chromium-pickle-js@0.2.0","symbols":["createEmpty","createFromBuffer"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-chromium-pickle-js",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-chromium-pickle-js",
      "version": "1.0.0",
      "dependencies": {
        "chromium-pickle-js": "0.2.0"
      }
    },
    "node_modules/chromium-pickle-js": {
      "version": "0.2.0",
      "resolved": "https://registry.npmjs.org/chromium-pickle-js/-/chromium-pickle-js-0.2.0.tgz",
      "integrity": "sha512-1R5Fho+jBq0DDydt+/vHWj5KJNJCKdARKOCwZUen84I5BreWoLqRLANH1U87eJy1tiASPtMnGqJJq0ZsLoRPOw==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-chromium-pickle-js",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "chromium-pickle-js": "0.2.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/chromium-pickle-js@0.2.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/chromium-pickle-js@0.2.0"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

import pickle from 'chromium-pickle-js';

const { createEmpty, createFromBuffer } = pickle;

/**
 * Creates an empty Pickle instance for writing binary data.
 * @returns {object}
 */
export function createEmptyPickle() {
  return createEmpty();
}

/**
 * Creates a Pickle instance from an existing Buffer for reading.
 * @param {Buffer} buffer
 * @returns {object}
 */
export function createPickleFromBuffer(buffer) {
  return createFromBuffer(buffer);
}

export { createEmpty, createFromBuffer };

import assert from 'node:assert/strict';
import {
  createEmpty,
  createFromBuffer,
  createEmptyPickle,
  createPickleFromBuffer,
} from '../src/index.mjs';

// 1. createEmpty returns a new Pickle instance that can write bool, int, uint32, float, double, and string primitives
{
  const p = createEmptyPickle();
  assert.equal(p.writeBool(true), true);
  assert.equal(p.writeBool(false), true);
  assert.equal(p.writeInt(-12345), true);
  assert.equal(p.writeUInt32(54321), true);
  assert.equal(p.writeFloat(1.5), true);
  assert.equal(p.writeDouble(3.141592653589793), true);
  assert.equal(p.writeString('chromium-pickle-sample'), true);
}

// 2. Pickle.toBuffer returns a Buffer containing the 4-byte payload size header followed by 4-byte aligned payload data
{
  const p = createEmpty();
  assert.equal(p.writeInt(42), true);
  const buf = p.toBuffer();
  assert.ok(Buffer.isBuffer(buf));
  const payloadSize = buf.readUInt32LE(0);
  assert.equal(payloadSize, 4);
  assert.equal(buf.length, 8);
  assert.equal(buf.readInt32LE(4), 42);
}

// 3. createFromBuffer initializes a Pickle instance from an existing Buffer for reading with PickleIterator
{
  const pWrite = createEmpty();
  assert.equal(pWrite.writeString('read-test'), true);
  const buf = pWrite.toBuffer();

  const pRead = createPickleFromBuffer(buf);
  const it = pRead.createIterator();
  assert.equal(it.readString(), 'read-test');
}

// 4. PickleIterator sequentially reads bool, int, uint32, float, double, and string values in matching write order
{
  const p = createEmpty();
  assert.equal(p.writeBool(true), true);
  assert.equal(p.writeBool(false), true);
  assert.equal(p.writeInt(-9876), true);
  assert.equal(p.writeUInt32(65432), true);
  assert.equal(p.writeFloat(2.5), true);
  assert.equal(p.writeDouble(2.718281828459045), true);
  assert.equal(p.writeString('sequential-test'), true);

  const buf = p.toBuffer();
  const pRead = createFromBuffer(buf);
  const it = pRead.createIterator();

  assert.equal(it.readBool(), true);
  assert.equal(it.readBool(), false);
  assert.equal(it.readInt(), -9876);
  assert.equal(it.readUInt32(), 65432);
  assert.equal(it.readFloat(), 2.5);
  assert.equal(it.readDouble(), 2.718281828459045);
  assert.equal(it.readString(), 'sequential-test');
}

// 5. Pickle.writeInt64 and Pickle.writeUInt64 throw TypeError in Node.js because 64-bit buffer write methods are undefined on Buffer.prototype
{
  const p = createEmpty();
  assert.throws(
    () => {
      p.writeInt64(100);
    },
    {
      name: 'TypeError',
    }
  );
  assert.throws(
    () => {
      p.writeUInt64(100);
    },
    {
      name: 'TypeError',
    }
  );
}

// 6. PickleIterator throws an Error when attempting to read past the payload buffer end
{
  const p = createEmpty();
  assert.equal(p.writeInt(100), true);
  const buf = p.toBuffer();

  const pRead = createFromBuffer(buf);
  const it = pRead.createIterator();
  assert.equal(it.readInt(), 100);

  assert.throws(
    () => {
      it.readInt();
    },
    {
      name: 'Error',
      message: /Failed to read data with length of/,
    }
  );
}

console.log('Contract assertions passed.');