readable-stream 2.3.8: PassThrough

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 readable-stream.PassThrough in pkg:npm/readable-stream@2.3.8
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/readable-stream@2.3.8
Demonstrate these symbols/APIs:
  - readable-stream.PassThrough

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:sha256:9a1715e9af134eeb9ee57711b8e5d2ab643019fe06caaa8ced699da81c5ed9b4","contract":["PassThrough stream can be instantiated and exposes stream methods","PassThrough stream passes written buffer chunks through unmodified in paused mode","PassThrough stream supports flowing mode with data and end events","PassThrough stream supports objectMode for passing non-buffer objects"],"goal":"verify readable-stream.PassThrough in pkg:npm/readable-stream@2.3.8","kind":"HOW","packages":["pkg:npm/readable-stream@2.3.8"],"schemaVersion":1,"symbols":["readable-stream.PassThrough"]},"contractCommand":["node","test/contract.js"],"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/readable-stream@2.3.8"],"schemaVersion":1,"subject":"pkg:npm/readable-stream@2.3.8","symbols":["readable-stream.PassThrough"],"verifierAdapter":"node-typescript@1"}

const { PassThrough } = require('readable-stream');

/**
 * Creates a PassThrough stream instance with optional configuration.
 *
 * @param {object} [options]
 * @returns {PassThrough}
 */
function createPassThrough(options) {
  return new PassThrough(options);
}

/**
 * Feeds an array of chunks into a PassThrough stream and collects the output Buffer.
 *
 * @param {Buffer[]|string[]} chunks
 * @param {object} [options]
 * @returns {Promise<Buffer>}
 */
function passThroughBuffer(chunks, options) {
  return new Promise((resolve, reject) => {
    const pt = new PassThrough(options);
    const collected = [];

    pt.on('data', (chunk) => {
      collected.push(Buffer.isBuffer(chunk) ? chunk : Buffer.from(chunk));
    });

    pt.on('end', () => {
      resolve(Buffer.concat(collected));
    });

    pt.on('error', (err) => {
      reject(err);
    });

    for (const chunk of chunks) {
      pt.write(chunk);
    }
    pt.end();
  });
}

module.exports = {
  PassThrough,
  createPassThrough,
  passThroughBuffer,
};

{
  "name": "sample-readable-stream-passthrough",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-readable-stream-passthrough",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "readable-stream": "2.3.8"
      }
    },
    "node_modules/core-util-is": {
      "version": "1.0.3",
      "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.3.tgz",
      "integrity": "sha512-ZQBvi1DcpJ4GDqanjucZ2Hj3wEO5pZDS89BWbkcrvdxksJorwUDDZamX9ldFkp9aw2lmBDLgkObEA4DWNJ9FYQ==",
      "license": "MIT"
    },
    "node_modules/inherits": {
      "version": "2.0.4",
      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.4.tgz",
      "integrity": "sha512-k/vGaX4/Yla3WzyMCvTQOXYeIHvqOKtnqBduzTHpzpQZzAskKMhZ2K+EnBiSM9zGSoIFeMpXKxa4dYeZIQqewQ==",
      "license": "ISC"
    },
    "node_modules/isarray": {
      "version": "1.0.0",
      "resolved": "https://registry.npmjs.org/isarray/-/isarray-1.0.0.tgz",
      "integrity": "sha512-VLghIWNM6ELQzo7zwmcg0NmTVyWKYjvIeM83yjp0wRDTmUnrM678fQbcKBo6n2CJEF0szoG//ytg+TKla89ALQ==",
      "license": "MIT"
    },
    "node_modules/process-nextick-args": {
      "version": "2.0.1",
      "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-2.0.1.tgz",
      "integrity": "sha512-3ouUOpQhtgrbOa17J7+uxOTpITYWaGP7/AhoR3+A+/1e9skrzelGi/dXzEYyvbxubEF6Wn2ypscTKiKJFFn1ag==",
      "license": "MIT"
    },
    "node_modules/readable-stream": {
      "version": "2.3.8",
      "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-2.3.8.tgz",
      "integrity": "sha512-8p0AUk4XODgIewSi0l8Epjs+EVnWiK7NoDIEGU0HhE7+ZyY8D1IMY7odu5lRrFXGg71L15KG8QrPmum45RTtdA==",
      "license": "MIT",
      "dependencies": {
        "core-util-is": "~1.0.0",
        "inherits": "~2.0.3",
        "isarray": "~1.0.0",
        "process-nextick-args": "~2.0.0",
        "safe-buffer": "~5.1.1",
        "string_decoder": "~1.1.1",
        "util-deprecate": "~1.0.1"
      }
    },
    "node_modules/safe-buffer": {
      "version": "5.1.2",
      "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.2.tgz",
      "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g==",
      "license": "MIT"
    },
    "node_modules/string_decoder": {
      "version": "1.1.1",
      "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.1.1.tgz",
      "integrity": "sha512-n/ShnvDi6FHbbVfviro+WojiFzv+s8MPMHBczVePfUpDJLwoLT0ht1l4YwBCbi8pJAveEEdnkHyPyTP/mzRfwg==",
      "license": "MIT",
      "dependencies": {
        "safe-buffer": "~5.1.0"
      }
    },
    "node_modules/util-deprecate": {
      "version": "1.0.2",
      "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
      "integrity": "sha512-EPD5q1uXyFxJpCrLnCc1nHnq3gOa6DZBocAIiI2TaSCA7VCJ1UJDMagCzIkXNsUYfD1daK//LTEQ8xiIbrHtcw==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-readable-stream-passthrough",
  "version": "1.0.0",
  "description": "Verify readable-stream PassThrough stream behavior",
  "main": "index.js",
  "scripts": {
    "test": "node test/contract.js"
  },
  "dependencies": {
    "readable-stream": "2.3.8"
  },
  "license": "MIT-0"
}

{
  "schemaVersion": 1,
  "goal": "verify readable-stream.PassThrough in pkg:npm/readable-stream@2.3.8",
  "kind": "HOW",
  "packages": [
    "pkg:npm/readable-stream@2.3.8"
  ],
  "symbols": [
    "readable-stream.PassThrough"
  ]
}

const assert = require('node:assert');
const { PassThrough, createPassThrough, passThroughBuffer } = require('../index.js');

async function main() {
  // 1. Instantiation and basic interface
  {
    const pt = createPassThrough();
    assert.strictEqual(pt instanceof PassThrough, true);
    assert.strictEqual(typeof pt.write, 'function');
    assert.strictEqual(typeof pt.read, 'function');
    assert.strictEqual(typeof pt.pipe, 'function');
  }

  // 2. Data written is read back unmodified in paused mode
  {
    const pt = new PassThrough();
    const input = Buffer.from('hello-passthrough');
    pt.write(input);
    pt.end();

    const output = pt.read();
    assert.deepStrictEqual(output, input);
  }

  // 3. Flowing mode with data and end events via passThroughBuffer
  {
    const chunks = [
      Buffer.from('alpha-'),
      Buffer.from('beta-'),
      Buffer.from('gamma'),
    ];
    const result = await passThroughBuffer(chunks);
    assert.strictEqual(result.toString('utf8'), 'alpha-beta-gamma');
  }

  // 4. Object mode pass-through
  {
    const pt = new PassThrough({ objectMode: true });
    const collected = [];

    pt.on('data', (item) => {
      collected.push(item);
    });

    pt.write({ key: 'value1' });
    pt.write({ key: 'value2' });
    pt.end();

    await new Promise((resolve) => pt.on('end', resolve));

    assert.strictEqual(collected.length, 2);
    assert.deepStrictEqual(collected[0], { key: 'value1' });
    assert.deepStrictEqual(collected[1], { key: 'value2' });
  }

  console.log('Contract test passed successfully.');
}

main().catch((err) => {
  console.error('Contract test failed:', err);
  process.exit(1);
});