delayed-stream 1.0.0

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/delayed-stream@1.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/delayed-stream@1.0.0
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - 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:sha256:9fdcae59bcbe91bfc84f3bf3a34818086d3623498837c4c998b2ec60c2116264","constraints":{"executionContext":"node"},"contract":["DelayedStream.create wraps a source stream with default or custom options","DelayedStream buffers events emitted by the source before resume is called","DelayedStream flushes buffered events in chronological order on resume","DelayedStream continues forwarding real-time events after release","DelayedStream.prototype.pipe transmits buffered and incoming data to destination writable stream","DelayedStream emits error event when buffered data exceeds maxDataSize limit","DelayedStream.prototype.setEncoding proxies encoding settings to the source stream"],"goal":"verify pkg:npm/delayed-stream@1.0.0","kind":"HOW","packages":["pkg:npm/delayed-stream@1.0.0"],"schemaVersion":1},"contractCommand":["node","test/contract.cjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","executionContext":"node","language":"javascript","libc":"glibc","libcVersion":"2.39","moduleSystem":"cjs","os":"linux","osVersionBucket":"24","packageManager":"npm","runtime":"node","runtimeVersion":"22.23.2","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/delayed-stream@1.0.0"],"schemaVersion":1,"subject":"pkg:npm/delayed-stream@1.0.0","verifierAdapter":"node-typescript@1"}

{
  "name": "delayed-stream-verification",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "delayed-stream-verification",
      "version": "1.0.0",
      "dependencies": {
        "delayed-stream": "1.0.0"
      }
    },
    "node_modules/delayed-stream": {
      "version": "1.0.0",
      "resolved": "https://registry.npmjs.org/delayed-stream/-/delayed-stream-1.0.0.tgz",
      "integrity": "sha512-ZySD7Nf91aLB0RxL4KGrKHBXl7Eds1DAmEdcoVawXnLD7SDhpNgtuII2aAkg7a7QS41jxPSZ17p4VdGnMHk3MQ==",
      "license": "MIT",
      "engines": {
        "node": ">=0.4.0"
      }
    }
  }
}

{
  "name": "delayed-stream-verification",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification for delayed-stream",
  "dependencies": {
    "delayed-stream": "1.0.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/delayed-stream@1.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/delayed-stream@1.0.0"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "runtime": "node@22.23.2"
  }
}

const assert = require('node:assert');
const { PassThrough, Writable } = require('node:stream');
const EventEmitter = require('node:events');
const DelayedStream = require('delayed-stream');

async function runContractTests() {
  // 1. DelayedStream.create wraps a source stream with default or custom options
  const ptDefault = new PassThrough();
  const dsDefault = DelayedStream.create(ptDefault);
  assert.strictEqual(dsDefault.source, ptDefault);
  assert.strictEqual(dsDefault.maxDataSize, 1024 * 1024);
  assert.strictEqual(dsDefault.pauseStream, true);

  const ptCustom = new PassThrough();
  const dsCustom = DelayedStream.create(ptCustom, { maxDataSize: 2048, pauseStream: false });
  assert.strictEqual(dsCustom.maxDataSize, 2048);
  assert.strictEqual(dsCustom.pauseStream, false);

  // 2. DelayedStream buffers events emitted by the source before resume is called
  const source2 = new EventEmitter();
  source2.pause = () => {};
  source2.resume = () => {};
  const ds2 = DelayedStream.create(source2);

  let receivedBeforeResume = 0;
  ds2.on('data', () => { receivedBeforeResume++; });

  source2.emit('data', Buffer.from('hello '));
  source2.emit('data', Buffer.from('world'));
  source2.emit('custom-event', 42);

  assert.strictEqual(receivedBeforeResume, 0);
  assert.strictEqual(ds2._bufferedEvents.length, 3);
  assert.strictEqual(ds2.dataSize, 11);

  // 3. DelayedStream flushes buffered events in chronological order on resume
  const eventsReceived = [];
  let customValue = null;
  ds2.on('data', chunk => eventsReceived.push(chunk.toString()));
  ds2.on('custom-event', val => { customValue = val; });

  ds2.resume();

  assert.deepStrictEqual(eventsReceived, ['hello ', 'world']);
  assert.strictEqual(customValue, 42);
  assert.strictEqual(ds2._bufferedEvents.length, 0);

  // 4. DelayedStream continues forwarding real-time events after release
  source2.emit('data', Buffer.from('!'));
  assert.deepStrictEqual(eventsReceived, ['hello ', 'world', '!']);

  // 5. DelayedStream.prototype.pipe transmits buffered and incoming data to destination writable stream
  const source5 = new PassThrough();
  const ds5 = DelayedStream.create(source5);

  source5.write('chunk-1;');
  source5.write('chunk-2;');

  let pipedOutput = '';
  const destination = new Writable({
    write(chunk, encoding, callback) {
      pipedOutput += chunk.toString();
      callback();
    }
  });

  const pipedPromise = new Promise(resolve => {
    destination.on('finish', resolve);
  });

  ds5.pipe(destination);
  source5.write('chunk-3');
  source5.end();

  await pipedPromise;
  assert.strictEqual(pipedOutput, 'chunk-1;chunk-2;chunk-3');

  // 6. DelayedStream emits error event when buffered data exceeds maxDataSize limit
  const source6 = new EventEmitter();
  source6.pause = () => {};
  source6.resume = () => {};
  const ds6 = DelayedStream.create(source6, { maxDataSize: 10 });

  let errorCaught = null;
  ds6.on('error', err => { errorCaught = err; });

  source6.emit('data', Buffer.from('small'));
  assert.strictEqual(errorCaught, null);
  source6.emit('data', Buffer.from('exceeding-the-limit'));
  assert(errorCaught instanceof Error);
  assert(errorCaught.message.includes('DelayedStream#maxDataSize of 10 bytes exceeded'));

  // 7. DelayedStream.prototype.setEncoding proxies encoding settings to the source stream
  const source7 = new PassThrough();
  const ds7 = DelayedStream.create(source7);
  ds7.setEncoding('utf8');
  assert.strictEqual(source7.readableEncoding, 'utf8');

  console.log('DelayedStream contract verified successfully.');
}

runContractTests().catch(err => {
  console.error(err);
  process.exit(1);
});