streamx 2.28.0

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/streamx@2.28.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/streamx@2.28.0

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:sha256:90ae5c8facd2d514044261f03a384620e52d00b5212dda90cdc5826b3bcfdfd8","contract":["Readable stream emits data and end events when chunks are pushed and ended with null","Writable stream buffers written chunks, calls write handler, and emits finish when ended","Transform stream transforms incoming chunks in transform handler and forwards to downstream consumers","pipeline successfully pipes data from Readable through Transform to Writable and calls completion callback","pipelinePromise asynchronously connects streams and resolves when data transfer finishes","PassThrough stream transfers input chunks unmodified to reader","Readable stream supports async iteration yielding each pushed chunk","Stream emits error and close events when destroyed with an error"],"goal":"verify pkg:npm/streamx@2.28.0","kind":"HOW","packages":["pkg:npm/streamx@2.28.0"],"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/streamx@2.28.0"],"schemaVersion":1,"subject":"pkg:npm/streamx@2.28.0","verifierAdapter":"node-typescript@1"}

{
  "name": "sample-streamx",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-streamx",
      "version": "1.0.0",
      "dependencies": {
        "streamx": "2.28.0"
      }
    },
    "node_modules/b4a": {
      "version": "1.8.1",
      "resolved": "https://registry.npmjs.org/b4a/-/b4a-1.8.1.tgz",
      "integrity": "sha512-aiqre1Nr0B/6DgE2N5vwTc+2/oQZ4Wh1t4NznYY4E00y8LCt6NqdRv81so00oo27D8MVKTpUa/MwUUtBLXCoDw==",
      "license": "Apache-2.0",
      "peerDependencies": {
        "react-native-b4a": "*"
      },
      "peerDependenciesMeta": {
        "react-native-b4a": {
          "optional": true
        }
      }
    },
    "node_modules/bare-events": {
      "version": "2.9.1",
      "resolved": "https://registry.npmjs.org/bare-events/-/bare-events-2.9.1.tgz",
      "integrity": "sha512-Z0oHEHAFDZkffN8Qc39zNZjQlMDkPJRyyyZieU1VH7u8c5S+qHZ2S8ixdKIAxEjfHO7FJxXmJWgteOghVanIsg==",
      "license": "Apache-2.0",
      "peerDependencies": {
        "bare-abort-controller": "*"
      },
      "peerDependenciesMeta": {
        "bare-abort-controller": {
          "optional": true
        }
      }
    },
    "node_modules/events-universal": {
      "version": "1.0.1",
      "resolved": "https://registry.npmjs.org/events-universal/-/events-universal-1.0.1.tgz",
      "integrity": "sha512-LUd5euvbMLpwOF8m6ivPCbhQeSiYVNb8Vs0fQ8QjXo0JTkEHpz8pxdQf0gStltaPpw0Cca8b39KxvK9cfKRiAw==",
      "license": "Apache-2.0",
      "dependencies": {
        "bare-events": "^2.7.0"
      }
    },
    "node_modules/fast-fifo": {
      "version": "1.3.2",
      "resolved": "https://registry.npmjs.org/fast-fifo/-/fast-fifo-1.3.2.tgz",
      "integrity": "sha512-/d9sfos4yxzpwkDkuN7k2SqFKtYNmCTzgfEpz82x34IM9/zc8KGxQoXg1liNC/izpRM/MBdt44Nmx41ZWqk+FQ==",
      "license": "MIT"
    },
    "node_modules/streamx": {
      "version": "2.28.0",
      "resolved": "https://registry.npmjs.org/streamx/-/streamx-2.28.0.tgz",
      "integrity": "sha512-1Yowhzjf0ivGMrTIkY9hav5TxobO9qIVqUE41fiCGMGgc3CLlf4MY+9AHmZqBWgDTue0fY9zWjYFVyf6Diuobw==",
      "license": "MIT",
      "dependencies": {
        "events-universal": "^1.0.0",
        "fast-fifo": "^1.3.2",
        "text-decoder": "^1.1.0"
      }
    },
    "node_modules/text-decoder": {
      "version": "1.2.7",
      "resolved": "https://registry.npmjs.org/text-decoder/-/text-decoder-1.2.7.tgz",
      "integrity": "sha512-vlLytXkeP4xvEq2otHeJfSQIRyWxo/oZGEbXrtEEF9Hnmrdly59sUbzZ/QgyWuLYHctCHxFF4tRQZNQ9k60ExQ==",
      "license": "Apache-2.0",
      "dependencies": {
        "b4a": "^1.6.4"
      }
    }
  }
}

{
  "name": "sample-streamx",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "streamx": "2.28.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify pkg:npm/streamx@2.28.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/streamx@2.28.0"
  ]
}

import assert from 'node:assert/strict';
import { Readable, Writable, Transform, PassThrough, pipeline, pipelinePromise } from 'streamx';

// 1. Readable stream emits data and end events when chunks are pushed and ended with null
await new Promise((resolve, reject) => {
  const chunks = [];
  const readable = new Readable({
    read(cb) {
      this.push('chunk1');
      this.push('chunk2');
      this.push(null);
      cb(null);
    }
  });

  readable.on('data', (chunk) => {
    chunks.push(chunk);
  });

  readable.on('end', () => {
    try {
      assert.deepEqual(chunks, ['chunk1', 'chunk2']);
      resolve();
    } catch (err) {
      reject(err);
    }
  });

  readable.on('error', reject);
});

// 2. Writable stream buffers written chunks, calls write handler, and emits finish when ended
await new Promise((resolve, reject) => {
  const received = [];
  const writable = new Writable({
    write(data, cb) {
      received.push(data);
      cb(null);
    }
  });

  writable.on('finish', () => {
    try {
      assert.deepEqual(received, ['item1', 'item2']);
      resolve();
    } catch (err) {
      reject(err);
    }
  });

  writable.on('error', reject);

  writable.write('item1');
  writable.write('item2');
  writable.end();
});

// 3. Transform stream transforms incoming chunks in transform handler and forwards to downstream consumers
await new Promise((resolve, reject) => {
  const transformed = [];
  const transform = new Transform({
    transform(data, cb) {
      this.push(data.toUpperCase());
      cb(null);
    }
  });

  transform.on('data', (data) => {
    transformed.push(data);
  });

  transform.on('end', () => {
    try {
      assert.deepEqual(transformed, ['HELLO', 'WORLD']);
      resolve();
    } catch (err) {
      reject(err);
    }
  });

  transform.on('error', reject);

  transform.write('hello');
  transform.write('world');
  transform.end();
});

// 4. pipeline successfully pipes data from Readable through Transform to Writable and calls completion callback
await new Promise((resolve, reject) => {
  const src = new Readable({
    read(cb) {
      this.push('foo');
      this.push('bar');
      this.push(null);
      cb(null);
    }
  });

  const tr = new Transform({
    transform(data, cb) {
      this.push(data + '!');
      cb(null);
    }
  });

  const destResult = [];
  const dest = new Writable({
    write(data, cb) {
      destResult.push(data);
      cb(null);
    }
  });

  pipeline(src, tr, dest, (err) => {
    if (err) return reject(err);
    try {
      assert.deepEqual(destResult, ['foo!', 'bar!']);
      resolve();
    } catch (e) {
      reject(e);
    }
  });
});

// 5. pipelinePromise asynchronously connects streams and resolves when data transfer finishes
await (async () => {
  const src = new Readable({
    read(cb) {
      this.push('apple');
      this.push('banana');
      this.push(null);
      cb(null);
    }
  });

  const destResult = [];
  const dest = new Writable({
    write(data, cb) {
      destResult.push(data);
      cb(null);
    }
  });

  await pipelinePromise(src, dest);
  assert.deepEqual(destResult, ['apple', 'banana']);
})();

// 6. PassThrough stream transfers input chunks unmodified to reader
await new Promise((resolve, reject) => {
  const pass = new PassThrough();
  const chunks = [];

  pass.on('data', (chunk) => {
    chunks.push(chunk);
  });

  pass.on('end', () => {
    try {
      assert.deepEqual(chunks, ['a', 'b', 'c']);
      resolve();
    } catch (err) {
      reject(err);
    }
  });

  pass.on('error', reject);

  pass.write('a');
  pass.write('b');
  pass.write('c');
  pass.end();
});

// 7. Readable stream supports async iteration yielding each pushed chunk
await (async () => {
  const readable = new Readable({
    read(cb) {
      this.push(10);
      this.push(20);
      this.push(30);
      this.push(null);
      cb(null);
    }
  });

  const items = [];
  for await (const chunk of readable) {
    items.push(chunk);
  }

  assert.deepEqual(items, [10, 20, 30]);
})();

// 8. Stream emits error and close events when destroyed with an error
await new Promise((resolve, reject) => {
  const readable = new Readable({
    read(cb) {
      cb(null);
    }
  });

  let errorFired = false;
  let closeFired = false;

  readable.on('error', (err) => {
    if (err.message === 'custom failure') {
      errorFired = true;
    }
  });

  readable.on('close', () => {
    try {
      assert.equal(errorFired, true);
      assert.equal(readable.destroyed, true);
      resolve();
    } catch (e) {
      reject(e);
    }
  });

  readable.destroy(new Error('custom failure'));
});