write-file-atomic 6.0.0: sync

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 write-file-atomic.sync in pkg:npm/write-file-atomic@6.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/write-file-atomic@6.0.0
Demonstrate these symbols/APIs:
  - write-file-atomic.sync

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:c8b650a17bbdb864ce38f5755bb7c9fbb93f9e9a5441c9df00a507d8b462638d","contract":["writeFileAtomic.sync(filename, data, options) atomically writes string or Buffer/TypedArray data to a temporary file via imurmurhash and renames it over filename.","Passing options.mode sets file permissions on creation, and subsequent writeFileAtomic.sync calls without options.mode preserve existing file permissions.","options.tmpfileCreated(tmpfile) is invoked synchronously after opening the temporary file and before rename removes the temporary path."],"goal":"verify write-file-atomic.sync in pkg:npm/write-file-atomic@6.0.0","kind":"HOW","packages":["pkg:npm/write-file-atomic@6.0.0"],"schemaVersion":1,"symbols":["write-file-atomic.sync"]},"contractCommand":["node","test/contract.mjs"],"environment":{"arch":"x64","distro":"ubuntu","ecosystem":"npm","libc":"glibc","libcVersion":"2.39","os":"linux","osVersionBucket":"24","packageManager":"npm","schemaVersion":1},"license":"MIT-0","packages":["pkg:npm/write-file-atomic@6.0.0"],"schemaVersion":1,"subject":"pkg:npm/write-file-atomic@6.0.0","symbols":["write-file-atomic.sync"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-write-file-atomic-sync",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-write-file-atomic-sync",
      "version": "1.0.0",
      "dependencies": {
        "write-file-atomic": "6.0.0"
      }
    },
    "node_modules/imurmurhash": {
      "version": "0.1.4",
      "resolved": "https://registry.npmjs.org/imurmurhash/-/imurmurhash-0.1.4.tgz",
      "integrity": "sha512-JmXMZ6wuvDmLiHEml9ykzqO6lwFbof0GG4IkcGaENdCRDDmMVnny7s5HsIgHCbaq0w2MyPhDqkhTUgS2LU2PHA==",
      "license": "MIT",
      "engines": {
        "node": ">=0.8.19"
      }
    },
    "node_modules/signal-exit": {
      "version": "4.1.0",
      "resolved": "https://registry.npmjs.org/signal-exit/-/signal-exit-4.1.0.tgz",
      "integrity": "sha512-bzyZ1e88w9O1iNJbKnOlvYTrWPDl46O1bG0D3XInv+9tkPrxrN8jUUTiFlDkkmKWgn1M6CfIA13SuGqOa9Korw==",
      "license": "ISC",
      "engines": {
        "node": ">=14"
      },
      "funding": {
        "url": "https://github.com/sponsors/isaacs"
      }
    },
    "node_modules/write-file-atomic": {
      "version": "6.0.0",
      "resolved": "https://registry.npmjs.org/write-file-atomic/-/write-file-atomic-6.0.0.tgz",
      "integrity": "sha512-GmqrO8WJ1NuzJ2DrziEI2o57jKAVIQNf8a18W3nCYU3H7PNWqCCVTeH6/NQE93CIllIgQS98rrmVkYgTX9fFJQ==",
      "license": "ISC",
      "dependencies": {
        "imurmurhash": "^0.1.4",
        "signal-exit": "^4.0.1"
      },
      "engines": {
        "node": "^18.17.0 || >=20.5.0"
      }
    }
  }
}

{
  "name": "sample-write-file-atomic-sync",
  "version": "1.0.0",
  "private": true,
  "type": "module",
  "scripts": {
    "test": "node test/contract.mjs"
  },
  "dependencies": {
    "write-file-atomic": "6.0.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify write-file-atomic.sync in pkg:npm/write-file-atomic@6.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/write-file-atomic@6.0.0"
  ],
  "symbols": [
    "write-file-atomic.sync"
  ]
}

import assert from 'node:assert/strict';
import fs from 'node:fs';
import os from 'node:os';
import path from 'node:path';
import writeFileAtomic from 'write-file-atomic';

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

try {
  // 1. Write string data with default utf8 encoding
  const file1 = path.join(tmpDir, 'text.txt');
  let createdTmpFile = null;
  writeFileAtomic.sync(file1, 'hello atomic', {
    mode: 0o600,
    tmpfileCreated(tmpfile) {
      createdTmpFile = tmpfile;
      assert.equal(fs.existsSync(tmpfile), true);
    }
  });

  assert.equal(typeof createdTmpFile, 'string');
  assert.equal(fs.existsSync(createdTmpFile), false);
  assert.equal(fs.readFileSync(file1, 'utf8'), 'hello atomic');
  const stat1 = fs.statSync(file1);
  assert.equal(stat1.mode & 0o777, 0o600);

  // 2. Overwrite existing file and preserve mode when options is an encoding string
  writeFileAtomic.sync(file1, 'updated content', 'utf8');
  assert.equal(fs.readFileSync(file1, 'utf8'), 'updated content');
  assert.equal(fs.statSync(file1).mode & 0o777, 0o600);

  // 3. Write Buffer (ArrayBufferView) with fsync: false
  const file2 = path.join(tmpDir, 'binary.bin');
  const buf = Buffer.from([0xde, 0xad, 0xbe, 0xef]);
  writeFileAtomic.sync(file2, buf, { fsync: false });
  assert.deepEqual(fs.readFileSync(file2), buf);
} finally {
  fs.rmSync(tmpDir, { recursive: true, force: true });
}