bare-stream 2.13.3: Writable

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.Writable 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.Writable
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:sha256:2af321f2ca1d50ee8c295e88b4f1c6a7ddf8e683fbd78f6f042be8c3739c3fd5","constraints":{"executionContext":"node"},"contract":["Writable processes written string chunks as buffers and emits finish event when ended","Writable executes open lifecycle hook before processing queued writes","Writable executes final callback after all writes finish before emitting finish event","Writable cork and uncork methods buffer writes before dispatching to destination","Writable end callback is invoked once the stream completes writing and isFinished returns true","Writable destroy emits error and close events while updating destroyed, closed, and errored properties","Custom Writable subclasses can override _write and _final to handle lifecycle data flow"],"goal":"verify bare-stream.Writable in pkg:npm/bare-stream@2.13.3","kind":"HOW","packages":["pkg:npm/bare-stream@2.13.3"],"schemaVersion":1,"symbols":["bare-stream.Writable"]},"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.Writable"],"verifierAdapter":"node-typescript@1"}

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

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

// 1. Writable processes written string chunks as buffers and emits finish event when ended
await new Promise((resolve, reject) => {
  const received = [];
  const writable = new Writable({
    write(chunk, encoding, cb) {
      assert.equal(Buffer.isBuffer(chunk), true);
      received.push(chunk.toString());
      cb(null);
    }
  });

  assert.equal(isStream(writable), true);
  assert.equal(isWritable(writable), true);

  writable.on('finish', () => {
    try {
      assert.deepEqual(received, ['hello', 'world']);
      assert.equal(isFinished(writable), true);
      resolve();
    } catch (e) {
      reject(e);
    }
  });
  writable.on('error', reject);

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

// 2. Writable executes open lifecycle hook before processing queued writes
await new Promise((resolve, reject) => {
  const order = [];
  const writable = new Writable({
    open(cb) {
      order.push('open');
      cb(null);
    },
    write(chunk, encoding, cb) {
      order.push(`write:${chunk.toString()}`);
      cb(null);
    }
  });

  writable.on('open', () => {
    order.push('event:open');
  });

  writable.on('finish', () => {
    try {
      assert.deepEqual(order, ['open', 'event:open', 'write:payload']);
      resolve();
    } catch (e) {
      reject(e);
    }
  });
  writable.on('error', reject);

  writable.write('payload');
  writable.end();
});

// 3. Writable executes final callback after all writes finish before emitting finish event
await new Promise((resolve, reject) => {
  const order = [];
  const writable = new Writable({
    write(chunk, encoding, cb) {
      order.push(`write:${chunk.toString()}`);
      cb(null);
    },
    final(cb) {
      order.push('final');
      cb(null);
    }
  });

  writable.on('finish', () => {
    try {
      assert.deepEqual(order, ['write:first', 'write:second', 'final']);
      resolve();
    } catch (e) {
      reject(e);
    }
  });
  writable.on('error', reject);

  writable.write('first');
  writable.write('second');
  writable.end();
});

// 4. Writable cork and uncork methods buffer writes before dispatching to destination
await new Promise((resolve, reject) => {
  const chunks = [];
  const writable = new Writable({
    write(chunk, encoding, cb) {
      chunks.push(chunk.toString());
      cb(null);
    }
  });

  writable.cork();
  writable.write('chunk-1');
  writable.write('chunk-2');
  writable.uncork();

  writable.on('finish', () => {
    try {
      assert.deepEqual(chunks, ['chunk-1', 'chunk-2']);
      resolve();
    } catch (e) {
      reject(e);
    }
  });
  writable.on('error', reject);

  writable.end();
});

// 5. Writable end callback is invoked once the stream completes writing and isFinished returns true
await new Promise((resolve, reject) => {
  let endCbCalled = false;
  const writable = new Writable({
    write(chunk, encoding, cb) {
      cb(null);
    }
  });

  writable.write('alpha');
  writable.end('beta', () => {
    endCbCalled = true;
    try {
      assert.equal(endCbCalled, true);
      assert.equal(isFinished(writable), true);
      resolve();
    } catch (e) {
      reject(e);
    }
  });
  writable.on('error', reject);
});

// 6. Writable destroy emits error and close events while updating destroyed, closed, and errored properties
await new Promise((resolve, reject) => {
  const writable = new Writable({
    write(chunk, encoding, cb) {
      cb(null);
    }
  });

  let errorEmitted = false;
  let closeEmitted = false;

  writable.on('error', (err) => {
    if (err.message === 'stream failure') {
      errorEmitted = true;
    }
  });

  writable.on('close', () => {
    closeEmitted = true;
    try {
      assert.equal(errorEmitted, true);
      assert.equal(closeEmitted, true);
      assert.equal(writable.destroyed, true);
      assert.equal(writable.closed, true);
      assert.equal(writable.errored?.message, 'stream failure');
      resolve();
    } catch (e) {
      reject(e);
    }
  });

  writable.destroy(new Error('stream failure'));
});

// 7. Custom Writable subclasses can override _write and _final to handle lifecycle data flow
await new Promise((resolve, reject) => {
  class CustomSink extends Writable {
    constructor(opts) {
      super(opts);
      this.sink = [];
    }
    _write(chunk, encoding, cb) {
      this.sink.push(chunk.toString());
      cb(null);
    }
    _final(cb) {
      this.sink.push('DONE');
      cb(null);
    }
  }

  const custom = new CustomSink();
  custom.on('finish', () => {
    try {
      assert.deepEqual(custom.sink, ['msgA', 'msgB', 'DONE']);
      resolve();
    } catch (e) {
      reject(e);
    }
  });
  custom.on('error', reject);

  custom.write('msgA');
  custom.write('msgB');
  custom.end();
});