graceful-fs 4.2.11: writeFileSync

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 graceful-fs.writeFileSync in pkg:npm/graceful-fs@4.2.11
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/graceful-fs@4.2.11
Demonstrate these symbols/APIs:
  - graceful-fs.writeFileSync

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:a91c5893887d010faacbb394d46c6a001ad66af5ada5aa17e7df9f714c4727e8","contract":["assert writeFileSync is exported as a function by graceful-fs","assert writeFileSync synchronously writes utf-8 text data to destination file","assert writeFileSync synchronously writes binary buffer data to destination file","assert writeFileSync supports options flag to append data to existing file","assert writeFileSync synchronously writes data to an open file descriptor","assert writeFileSync throws ENOENT error synchronously when target directory does not exist"],"goal":"verify graceful-fs.writeFileSync in pkg:npm/graceful-fs@4.2.11","kind":"HOW","packages":["pkg:npm/graceful-fs@4.2.11"],"schemaVersion":1,"symbols":["graceful-fs.writeFileSync"]},"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/graceful-fs@4.2.11"],"schemaVersion":1,"subject":"pkg:npm/graceful-fs@4.2.11","symbols":["graceful-fs.writeFileSync"],"verifierAdapter":"node-typescript@1"}

const gracefulFs = require('graceful-fs');

/**
 * Writes data synchronously to a file using graceful-fs writeFileSync.
 *
 * @param {string|Buffer|URL|number} file - Path to file or file descriptor.
 * @param {string|Buffer|Uint8Array} data - Data to write.
 * @param {object|string} [options] - Options or encoding.
 */
function writeFileSync(file, data, options) {
  return gracefulFs.writeFileSync(file, data, options);
}

module.exports = {
  gracefulFs,
  writeFileSync: gracefulFs.writeFileSync,
  writeToFileSync: writeFileSync,
};

{
  "name": "sample-graceful-fs-writefilesync",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-graceful-fs-writefilesync",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "graceful-fs": "4.2.11"
      }
    },
    "node_modules/graceful-fs": {
      "version": "4.2.11",
      "resolved": "https://registry.npmjs.org/graceful-fs/-/graceful-fs-4.2.11.tgz",
      "integrity": "sha512-RbJ5/jmFcNNCcDV5o9eTnBLJ/HszWV0P73bc+Ff4nS/rJj+YaS6IGyiOL0VoBYX+l1Wrl3k63h/KrH+nhJ0XvQ==",
      "license": "ISC"
    }
  }
}

{
  "name": "sample-graceful-fs-writefilesync",
  "version": "1.0.0",
  "description": "Clean-room sample verifying graceful-fs.writeFileSync in pkg:npm/graceful-fs@4.2.11",
  "main": "index.js",
  "type": "commonjs",
  "license": "MIT-0",
  "dependencies": {
    "graceful-fs": "4.2.11"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify graceful-fs.writeFileSync in pkg:npm/graceful-fs@4.2.11",
  "kind": "HOW",
  "packages": [
    "pkg:npm/graceful-fs@4.2.11"
  ],
  "symbols": [
    "graceful-fs.writeFileSync"
  ]
}

import assert from 'node:assert/strict';
import fs from 'node:fs';
import path from 'node:path';
import os from 'node:os';
import { createRequire } from 'node:module';

const require = createRequire(import.meta.url);
const {
  gracefulFs,
  writeFileSync,
  writeToFileSync,
} = require('../index.js');

const tmpDir = fs.mkdtempSync(path.join(os.tmpdir(), 'graceful-fs-write-sync-'));

try {
  // 1. assert writeFileSync is exported as a function by graceful-fs
  assert.strictEqual(typeof writeFileSync, 'function', 'writeFileSync must be a function');
  assert.strictEqual(typeof gracefulFs.writeFileSync, 'function', 'gracefulFs.writeFileSync must be a function');
  assert.strictEqual(typeof writeToFileSync, 'function', 'writeToFileSync helper must be a function');

  // 2. assert writeFileSync synchronously writes utf-8 text data to destination file
  const textFile = path.join(tmpDir, 'test-utf8.txt');
  const payload = 'graceful-fs-writefilesync-content-verification';
  writeToFileSync(textFile, payload, 'utf8');
  const textRead = gracefulFs.readFileSync(textFile, 'utf8');
  assert.strictEqual(textRead, payload, 'file content must match written payload');

  // 3. assert writeFileSync synchronously writes binary buffer data to destination file
  const binFile = path.join(tmpDir, 'test-bin.dat');
  const binData = Buffer.from([0x12, 0x34, 0x56, 0x78, 0x9a, 0xbc]);
  writeToFileSync(binFile, binData);
  const binRead = gracefulFs.readFileSync(binFile);
  assert.deepStrictEqual(binRead, binData, 'binary file content must match written buffer');

  // 4. assert writeFileSync supports options flag to append data to existing file
  const appendChunk = '\nappended-content';
  writeToFileSync(textFile, appendChunk, { flag: 'a', encoding: 'utf8' });
  const appendRead = gracefulFs.readFileSync(textFile, 'utf8');
  assert.strictEqual(appendRead, payload + appendChunk, 'appended content must be present at end of file');

  // 5. assert writeFileSync synchronously writes data to an open file descriptor
  const fdFile = path.join(tmpDir, 'test-fd.txt');
  const fd = gracefulFs.openSync(fdFile, 'w');
  try {
    gracefulFs.writeFileSync(fd, 'written-via-file-descriptor', 'utf8');
  } finally {
    gracefulFs.closeSync(fd);
  }
  const fdRead = gracefulFs.readFileSync(fdFile, 'utf8');
  assert.strictEqual(fdRead, 'written-via-file-descriptor', 'content written to fd must match');

  // 6. assert writeFileSync throws ENOENT error synchronously when target directory does not exist
  const nonexistentDirFile = path.join(tmpDir, 'nonexistent-directory', 'file.txt');
  assert.throws(
    () => writeToFileSync(nonexistentDirFile, 'data'),
    (err) => {
      assert.ok(err, 'writing to nonexistent directory must produce an error');
      assert.strictEqual(err.code, 'ENOENT', 'error code must be ENOENT');
      return true;
    }
  );

  console.log('Contract assertions passed successfully.');
} finally {
  fs.rmSync(tmpDir, { recursive: true, force: true });
}