fs.realpath 1.0.0: monkeypatch

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 fs.realpath.monkeypatch in pkg:npm/fs.realpath@1.0.0
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/fs.realpath@1.0.0
Demonstrate these symbols/APIs:
  - fs.realpath.monkeypatch

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:sha256:8de9f37d85e1959bc54c163a74e8e0baf5a6dbbec4d04d3ba2be0361a2f50e5c","contract":["assert monkeypatch replaces builtin fs.realpath with polyfill implementation","assert monkeypatch replaces builtin fs.realpathSync with polyfill sync implementation","assert isPatched returns true after applying monkeypatch","assert realpathSync resolves existing directory path while monkeypatched","assert realpath resolves existing directory path asynchronously while monkeypatched","assert realpathSync throws ENOENT when path does not exist while monkeypatched","assert unmonkeypatch restores fs.realpath to native implementation","assert unmonkeypatch restores fs.realpathSync to native implementation","assert isPatched returns false after unmonkeypatching"],"goal":"verify fs.realpath.monkeypatch in pkg:npm/fs.realpath@1.0.0","kind":"HOW","packages":["pkg:npm/fs.realpath@1.0.0"],"schemaVersion":1,"symbols":["fs.realpath.monkeypatch"]},"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/fs.realpath@1.0.0"],"schemaVersion":1,"subject":"pkg:npm/fs.realpath@1.0.0","symbols":["fs.realpath.monkeypatch"],"verifierAdapter":"node-typescript@1"}

const fs = require('fs');
const rp = require('fs.realpath');

function enableMonkeypatch() {
  rp.monkeypatch();
}

function disableMonkeypatch() {
  rp.unmonkeypatch();
}

function isPatched() {
  return fs.realpath === rp && fs.realpathSync === rp.sync;
}

function resolveRealPathSync(targetPath) {
  return fs.realpathSync(targetPath);
}

function resolveRealPathAsync(targetPath) {
  return new Promise((resolve, reject) => {
    fs.realpath(targetPath, (err, resolved) => {
      if (err) {
        reject(err);
      } else {
        resolve(resolved);
      }
    });
  });
}

module.exports = {
  enableMonkeypatch,
  disableMonkeypatch,
  isPatched,
  resolveRealPathSync,
  resolveRealPathAsync,
  rp,
};

{
  "name": "sample-fs-realpath",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-fs-realpath",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "fs.realpath": "1.0.0"
      }
    },
    "node_modules/fs.realpath": {
      "version": "1.0.0",
      "resolved": "https://registry.npmjs.org/fs.realpath/-/fs.realpath-1.0.0.tgz",
      "integrity": "sha512-OO0pH2lK6a0hZnAdau5ItzHPI6pUlvI7jMVnxUQRtw4owF2wk8lOSabtGDCTP4Ggrg2MbGnWO9X8K1t4+fGMDw==",
      "license": "ISC"
    }
  }
}

{
  "name": "sample-fs-realpath",
  "version": "1.0.0",
  "description": "Clean-room sample verifying fs.realpath.monkeypatch in fs.realpath",
  "main": "index.js",
  "license": "MIT-0",
  "dependencies": {
    "fs.realpath": "1.0.0"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify fs.realpath.monkeypatch in pkg:npm/fs.realpath@1.0.0",
  "kind": "HOW",
  "packages": [
    "pkg:npm/fs.realpath@1.0.0"
  ],
  "symbols": [
    "fs.realpath.monkeypatch"
  ]
}

import assert from 'node:assert';
import fs from 'node:fs';
import rp from 'fs.realpath';
import {
  enableMonkeypatch,
  disableMonkeypatch,
  isPatched,
  resolveRealPathSync,
  resolveRealPathAsync,
} from '../index.js';

const origRealpath = fs.realpath;
const origRealpathSync = fs.realpathSync;

// 1. Initial state: unpatched
assert.strictEqual(fs.realpath, origRealpath, 'Initial fs.realpath must match native implementation');
assert.strictEqual(fs.realpathSync, origRealpathSync, 'Initial fs.realpathSync must match native implementation');
assert.strictEqual(isPatched(), false, 'isPatched must return false before monkeypatch');

// 2. Apply monkeypatch
enableMonkeypatch();
assert.strictEqual(fs.realpath, rp, 'assert monkeypatch replaces builtin fs.realpath with polyfill implementation');
assert.strictEqual(fs.realpathSync, rp.sync, 'assert monkeypatch replaces builtin fs.realpathSync with polyfill sync implementation');
assert.strictEqual(isPatched(), true, 'assert isPatched returns true after applying monkeypatch');

// 3. Resolve existing directory path synchronously while patched
const resolvedSync = resolveRealPathSync('.');
assert.strictEqual(typeof resolvedSync, 'string', 'assert resolveRealPathSync returns string');
assert.ok(resolvedSync.length > 0, 'assert realpathSync resolves existing directory path while monkeypatched');

// 4. Resolve existing directory path asynchronously while patched
const resolvedAsync = await resolveRealPathAsync('.');
assert.strictEqual(resolvedAsync, resolvedSync, 'assert realpath resolves existing directory path asynchronously while monkeypatched');

// 5. Error handling for nonexistent path while patched
assert.throws(
  () => {
    resolveRealPathSync('./nonexistent_path_contract_check_404');
  },
  /ENOENT/,
  'assert realpathSync throws ENOENT when path does not exist while monkeypatched'
);

// 6. Restore original and verify unmonkeypatching
disableMonkeypatch();
assert.strictEqual(fs.realpath, origRealpath, 'assert unmonkeypatch restores fs.realpath to native implementation');
assert.strictEqual(fs.realpathSync, origRealpathSync, 'assert unmonkeypatch restores fs.realpathSync to native implementation');
assert.strictEqual(isPatched(), false, 'assert isPatched returns false after unmonkeypatching');

console.log('All fs.realpath.monkeypatch contract assertions passed.');