bare-stream 2.13.3: Duplex

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.Duplex 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.Duplex
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:sha256:14ce3dd0839503d46add036d18f83b008f6b8cd33e63727a346428b80c4eee9d","constraints":{"executionContext":"node"},"contract":["Duplex instance satisfies isStream, isReadable, and isWritable predicates","Duplex writable interface receives data chunks and triggers finish event and end callback","Duplex readable interface emits data events for pushed chunks and end event on null","Duplex unshift inserts chunk to be consumed next from readable stream","Duplex pipes output to a downstream writable stream","Duplex transforms input chunks to output stream via read and write handlers","Duplex toWeb and fromWeb converts stream to and from Web Streams","Duplex destroy emits error and close events and marks stream as destroyed"],"goal":"verify bare-stream.Duplex in pkg:npm/bare-stream@2.13.3","kind":"HOW","packages":["pkg:npm/bare-stream@2.13.3"],"schemaVersion":1,"symbols":["bare-stream.Duplex"]},"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.Duplex"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-bare-stream-duplex",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-bare-stream-duplex",
      "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-duplex",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "bare-stream": "2.13.3"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify bare-stream.Duplex in pkg:npm/bare-stream@2.13.3",
  "kind": "HOW",
  "packages": [
    "pkg:npm/bare-stream@2.13.3"
  ],
  "symbols": [
    "bare-stream.Duplex"
  ],
  "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 Stream, {
  Duplex,
  Writable,
  PassThrough,
  isStream,
  isReadable,
  isWritable,
  isEnded,
  isFinished
} from 'bare-stream';

// 1. Duplex instance satisfies isStream, isReadable, and isWritable predicates
{
  const duplex = new Duplex();
  assert.equal(isStream(duplex), true);
  assert.equal(isReadable(duplex), true);
  assert.equal(isWritable(duplex), true);
  assert.equal(duplex.destroyed, false);
}

// 2. Duplex writable interface receives data chunks and triggers finish event and end callback
await new Promise((resolve, reject) => {
  const written = [];
  const duplex = new Duplex({
    write(chunk, encoding, cb) {
      written.push(chunk.toString());
      cb(null);
    }
  });

  duplex.on('finish', () => {
    try {
      assert.deepEqual(written, ['ping', 'pong']);
      assert.equal(isFinished(duplex), true);
      resolve();
    } catch (err) {
      reject(err);
    }
  });
  duplex.on('error', reject);

  duplex.write('ping');
  duplex.end('pong', (err) => {
    if (err) reject(err);
  });
});

// 3. Duplex readable interface emits data events for pushed chunks and end event on null
await new Promise((resolve, reject) => {
  const items = ['alpha', 'beta'];
  let idx = 0;
  const duplex = new Duplex({
    read(size) {
      if (idx < items.length) {
        this.push(items[idx++]);
      } else {
        this.push(null);
      }
    }
  });

  const received = [];
  duplex.on('data', (chunk) => {
    received.push(chunk.toString());
  });

  duplex.on('end', () => {
    try {
      assert.deepEqual(received, ['alpha', 'beta']);
      assert.equal(isEnded(duplex), true);
      resolve();
    } catch (err) {
      reject(err);
    }
  });
  duplex.on('error', reject);
});

// 4. Duplex unshift inserts chunk to be consumed next from readable stream
await new Promise((resolve, reject) => {
  const duplex = new Duplex();
  duplex.push('second');
  duplex.unshift('first');
  duplex.push(null);

  const received = [];
  duplex.on('data', (chunk) => {
    received.push(chunk.toString());
  });

  duplex.on('end', () => {
    try {
      assert.deepEqual(received, ['first', 'second']);
      resolve();
    } catch (err) {
      reject(err);
    }
  });
  duplex.on('error', reject);
});

// 5. Duplex pipes output to a downstream writable stream
await new Promise((resolve, reject) => {
  let idx = 0;
  const items = ['data-1', 'data-2'];
  const duplex = new Duplex({
    read() {
      if (idx < items.length) {
        this.push(items[idx++]);
      } else {
        this.push(null);
      }
    }
  });

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

  dest.on('finish', () => {
    try {
      assert.deepEqual(sink, ['data-1', 'data-2']);
      resolve();
    } catch (err) {
      reject(err);
    }
  });
  dest.on('error', reject);
  duplex.pipe(dest);
});

// 6. Duplex transforms input chunks to output stream via read and write handlers
await new Promise((resolve, reject) => {
  const duplex = new Duplex({
    write(chunk, encoding, cb) {
      this.push(chunk.toString().toUpperCase());
      cb(null);
    },
    final(cb) {
      this.push(null);
      cb(null);
    }
  });

  const collected = [];
  duplex.on('data', (chunk) => {
    collected.push(chunk.toString());
  });

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

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

// 7. Duplex toWeb and fromWeb converts stream to and from Web Streams
{
  const duplex = new Duplex({
    write(chunk, encoding, cb) {
      cb(null);
    }
  });

  const webStream = Duplex.toWeb(duplex);
  assert.ok(webStream.readable);
  assert.ok(webStream.writable);

  const fromWebDuplex = Duplex.fromWeb(webStream);
  assert.equal(isStream(fromWebDuplex), true);
  assert.equal(isReadable(fromWebDuplex), true);
  assert.equal(isWritable(fromWebDuplex), true);
}

// 8. Duplex destroy emits error and close events and marks stream as destroyed
await new Promise((resolve, reject) => {
  const duplex = new Duplex();
  let errorSeen = false;

  duplex.on('error', (err) => {
    if (err.message === 'duplex stream destroyed') {
      errorSeen = true;
    }
  });

  duplex.on('close', () => {
    try {
      assert.equal(errorSeen, true);
      assert.equal(duplex.destroyed, true);
      resolve();
    } catch (err) {
      reject(err);
    }
  });

  duplex.destroy(new Error('duplex stream destroyed'));
});