bare-stream 2.13.3: 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 bare-stream.PassThrough in pkg:npm/bare-stream@2.13.3
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/bare-stream@2.13.3
Demonstrate these symbols/APIs:
  - bare-stream.PassThrough
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:sha256:14f3d5499ad8c3142eb035130845db52b5c64cf9fde501e0a90b8d828501e1f4","constraints":{"executionContext":"node"},"contract":["PassThrough forwards written string chunks unmodified to readable stream listeners","PassThrough supports streaming piping between readable and writable streams","PassThrough supports backpressure and pause/resume stream flow control","PassThrough integrates with pipeline utility for multi-stream chaining","PassThrough emits finish event when writing ends and end event when reading completes","PassThrough emits error and close events when destroyed with an error"],"goal":"verify bare-stream.PassThrough in pkg:npm/bare-stream@2.13.3","kind":"HOW","packages":["pkg:npm/bare-stream@2.13.3"],"schemaVersion":1,"symbols":["bare-stream.PassThrough"]},"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/bare-stream@2.13.3"],"schemaVersion":1,"subject":"pkg:npm/bare-stream@2.13.3","symbols":["bare-stream.PassThrough"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-bare-stream-passthrough",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-bare-stream-passthrough",
      "version": "1.0.0",
      "dependencies": {
        "bare-stream": "2.13.3"
      }
    },
    "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": "2.9.2",
      "resolved": "https://registry.npmjs.org/bare-events/-/bare-events-2.9.2.tgz",
      "integrity": "sha512-AIPKioV7/Y/8KfZ3AAhjPJxLLbY49S64Ym5DakZlUg75qQiTgUq9hEJoEwa4eUezPUlXRy/i5NpsKvo9jgKmoA==",
      "license": "Apache-2.0",
      "peerDependencies": {
        "bare-abort-controller": "*"
      },
      "peerDependenciesMeta": {
        "bare-abort-controller": {
          "optional": true
        }
      }
    },
    "node_modules/bare-stream": {
      "version": "2.13.3",
      "resolved": "https://registry.npmjs.org/bare-stream/-/bare-stream-2.13.3.tgz",
      "integrity": "sha512-Kc+brLqvEqGkjyfiwJmImAOqLZL7OsoLKuavx+hJjgVV3nLTOjloJyPMFxjUPerGGHrNH0fLU06jjykMLWrERQ==",
      "license": "Apache-2.0",
      "dependencies": {
        "b4a": "^1.8.1",
        "streamx": "^2.25.0",
        "teex": "^1.0.1"
      },
      "peerDependencies": {
        "bare-abort-controller": "*",
        "bare-buffer": "*",
        "bare-events": "*"
      },
      "peerDependenciesMeta": {
        "bare-abort-controller": {
          "optional": true
        },
        "bare-buffer": {
          "optional": true
        },
        "bare-events": {
          "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": "2.28.1",
      "resolved": "https://registry.npmjs.org/streamx/-/streamx-2.28.1.tgz",
      "integrity": "sha512-zEzXb0s5Cds7tqMH6rhZ05lcJydCWiQPEwiNngVqzsxCc962vLY4Uw+mW7od8kDH258k2Uz/JrOkdIAAhSh9VA==",
      "license": "MIT",
      "dependencies": {
        "events-universal": "^1.0.0",
        "fast-fifo": "^1.3.2",
        "text-decoder": "^1.1.0"
      }
    },
    "node_modules/teex": {
      "version": "1.0.1",
      "resolved": "https://registry.npmjs.org/teex/-/teex-1.0.1.tgz",
      "integrity": "sha512-eYE6iEI62Ni1H8oIa7KlDU6uQBtqr4Eajni3wX7rpfXD8ysFx8z0+dri+KWEPWpBsxXfxu58x/0jvTVT1ekOSg==",
      "license": "MIT",
      "dependencies": {
        "streamx": "^2.12.5"
      }
    },
    "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-bare-stream-passthrough",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "bare-stream": "2.13.3"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify bare-stream.PassThrough in pkg:npm/bare-stream@2.13.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/bare-stream@2.13.3"
  ],
  "symbols": [
    "bare-stream.PassThrough"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

import assert from 'node:assert/strict';
import {
  PassThrough,
  Readable,
  Writable,
  pipeline,
  isStream,
  isReadable,
  isWritable,
  isEnded,
  isFinished
} from 'bare-stream';

// 1. PassThrough forwards written string chunks unmodified to readable stream listeners
await new Promise((resolve, reject) => {
  const pass = new PassThrough();
  const chunks = [];

  assert.equal(isStream(pass), true);
  assert.equal(isReadable(pass), true);
  assert.equal(isWritable(pass), true);

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

  pass.on('end', () => {
    try {
      assert.deepEqual(chunks, ['hello ', 'world']);
      assert.equal(isEnded(pass), true);
      resolve();
    } catch (err) {
      reject(err);
    }
  });

  pass.on('error', reject);

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

// 2. PassThrough supports streaming piping between readable and writable streams
await new Promise((resolve, reject) => {
  let index = 0;
  const items = ['stream', 'data', 'transfer'];
  const src = new Readable({
    read() {
      if (index < items.length) {
        this.push(items[index++]);
      } else {
        this.push(null);
      }
    }
  });

  const pass = new PassThrough();
  const collected = [];
  const dest = new Writable({
    write(chunk, encoding, cb) {
      collected.push(chunk.toString());
      cb(null);
    }
  });

  dest.on('finish', () => {
    try {
      assert.deepEqual(collected, ['stream', 'data', 'transfer']);
      assert.equal(isFinished(dest), true);
      resolve();
    } catch (err) {
      reject(err);
    }
  });

  dest.on('error', reject);
  pass.on('error', reject);
  src.on('error', reject);

  src.pipe(pass).pipe(dest);
});

// 3. PassThrough supports backpressure and pause/resume stream flow control
await new Promise((resolve, reject) => {
  const pass = new PassThrough({ highWaterMark: 16 });
  const received = [];

  pass.pause();
  pass.write('buffered-chunk');

  // Should not emit data while paused
  pass.on('data', (chunk) => {
    received.push(chunk.toString());
  });

  assert.equal(received.length, 0);

  pass.resume();

  // After resume, buffered data is delivered
  setImmediate(() => {
    try {
      assert.equal(received.length, 1);
      assert.equal(received[0], 'buffered-chunk');
      resolve();
    } catch (err) {
      reject(err);
    }
  });
});

// 4. PassThrough integrates with pipeline utility for multi-stream chaining
await new Promise((resolve, reject) => {
  let count = 0;
  const words = ['pipe', 'line', 'test'];
  const src = new Readable({
    read() {
      if (count < words.length) {
        this.push(words[count++]);
      } else {
        this.push(null);
      }
    }
  });

  const pass1 = new PassThrough();
  const pass2 = new PassThrough();
  const result = [];
  const dest = new Writable({
    write(chunk, encoding, cb) {
      result.push(chunk.toString());
      cb(null);
    }
  });

  pipeline(src, pass1, pass2, dest, (err) => {
    if (err) return reject(err);
    try {
      assert.deepEqual(result, ['pipe', 'line', 'test']);
      resolve();
    } catch (e) {
      reject(e);
    }
  });
});

// 5. PassThrough emits finish event when writing ends and end event when reading completes
await new Promise((resolve, reject) => {
  const pass = new PassThrough();
  let finishFired = false;
  let endFired = false;

  pass.on('finish', () => {
    finishFired = true;
    assert.equal(isFinished(pass), true);
  });

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

  pass.on('end', () => {
    endFired = true;
    try {
      assert.equal(finishFired, true);
      assert.equal(endFired, true);
      assert.equal(isEnded(pass), true);
      resolve();
    } catch (err) {
      reject(err);
    }
  });

  pass.on('error', reject);

  pass.write('testing');
  pass.end();
});

// 6. PassThrough emits error and close events when destroyed with an error
await new Promise((resolve, reject) => {
  const pass = new PassThrough();
  let errorReceived = null;

  pass.on('error', (err) => {
    errorReceived = err;
  });

  pass.on('close', () => {
    try {
      assert.ok(errorReceived);
      assert.equal(errorReceived.message, 'passthrough failure');
      assert.equal(pass.destroyed, true);
      resolve();
    } catch (err) {
      reject(err);
    }
  });

  pass.destroy(new Error('passthrough failure'));
});