fs.realpath 1.0.0: 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 fs.realpath.sync 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.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:sha256:9beebad923895916d7f809c4bf5f39ff3e2ac6663a2cddeeca6a5fceaae45927","contract":["Resolving a canonical file path with fs.realpath.sync returns the resolved absolute path","Resolving a symbolic link with fs.realpath.sync returns the canonical target file path","Resolving nested symbolic links with fs.realpath.sync returns the final target file path","Resolving a path containing directory symlinks with fs.realpath.sync returns the canonical path through real directories","Passing a cache object to fs.realpath.sync returns the resolved path","Resolving a non-existent path with fs.realpath.sync throws an ENOENT error","Resolving a circular symbolic link with fs.realpath.sync throws an ELOOP error","fs.realpath.sync is a function exported on the fs.realpath module matching fs.realpath.realpathSync"],"goal":"verify fs.realpath.sync in pkg:npm/fs.realpath@1.0.0","kind":"HOW","packages":["pkg:npm/fs.realpath@1.0.0"],"schemaVersion":1,"symbols":["fs.realpath.sync"]},"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.sync"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-fs-realpath-sync",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-fs-realpath-sync",
      "version": "1.0.0",
      "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-sync",
  "version": "1.0.0",
  "type": "module",
  "private": true,
  "dependencies": {
    "fs.realpath": "1.0.0"
  }
}

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

import assert from 'node:assert/strict';
import fs from 'node:fs';
import os from 'node:os';
import path from 'node:path';
import fsRealpath from 'fs.realpath';

const { sync, realpathSync } = fsRealpath;

const tmpBase = fs.mkdtempSync(path.join(os.tmpdir(), 'csx-fs-realpath-sync-'));
const tmpDir = fs.realpathSync(tmpBase);

try {
	const targetFile = path.join(tmpDir, 'target.txt');
	fs.writeFileSync(targetFile, 'fs.realpath.sync test content', 'utf8');

	const linkFile = path.join(tmpDir, 'link.txt');
	fs.symlinkSync(targetFile, linkFile);

	const nestedLinkFile = path.join(tmpDir, 'nested-link.txt');
	fs.symlinkSync(linkFile, nestedLinkFile);

	// 1. Resolving a canonical file path with fs.realpath.sync returns the resolved absolute path
	const resolvedDirect = sync(targetFile);
	assert.equal(typeof resolvedDirect, 'string');
	assert.equal(resolvedDirect, targetFile);

	// 2. Resolving a symbolic link with fs.realpath.sync returns the canonical target file path
	const resolvedLink = sync(linkFile);
	assert.equal(resolvedLink, targetFile);

	// 3. Resolving nested symbolic links with fs.realpath.sync returns the final target file path
	const resolvedNested = sync(nestedLinkFile);
	assert.equal(resolvedNested, targetFile);

	// 4. Resolving a path containing directory symlinks with fs.realpath.sync returns the canonical path through real directories
	const dirTarget = path.join(tmpDir, 'real-dir');
	fs.mkdirSync(dirTarget);
	const fileInDir = path.join(dirTarget, 'file.txt');
	fs.writeFileSync(fileInDir, 'dir test content', 'utf8');
	const dirLink = path.join(tmpDir, 'link-dir');
	fs.symlinkSync(dirTarget, dirLink);
	const resolvedDirLink = sync(path.join(dirLink, 'file.txt'));
	assert.equal(resolvedDirLink, fileInDir);

	// 5. Passing a cache object to fs.realpath.sync returns the resolved path
	const cache = {};
	const resolvedCache = sync(targetFile, cache);
	assert.equal(resolvedCache, targetFile);

	// 6. Resolving a non-existent path with fs.realpath.sync throws an ENOENT error
	const nonExistent = path.join(tmpDir, 'non-existent.txt');
	assert.throws(
		() => sync(nonExistent),
		(err) => {
			assert.equal(err.code, 'ENOENT');
			return true;
		}
	);

	// 7. Resolving a circular symbolic link with fs.realpath.sync throws an ELOOP error
	const loopA = path.join(tmpDir, 'loop-a');
	const loopB = path.join(tmpDir, 'loop-b');
	fs.symlinkSync(loopB, loopA);
	fs.symlinkSync(loopA, loopB);
	assert.throws(
		() => sync(loopA),
		(err) => {
			assert.equal(err.code, 'ELOOP');
			return true;
		}
	);

	// 8. fs.realpath.sync is a function exported on the fs.realpath module matching fs.realpath.realpathSync
	assert.equal(typeof sync, 'function');
	assert.equal(sync, realpathSync);
} finally {
	fs.rmSync(tmpBase, { recursive: true, force: true });
}