@babel/helper-validator-identifier 8.0.4: isReservedWord

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 @babel/helper-validator-identifier.isReservedWord in pkg:npm/%40babel/helper-validator-identifier@8.0.4
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/%40babel/helper-validator-identifier@8.0.4
Demonstrate these symbols/APIs:
  - @babel/helper-validator-identifier.isReservedWord
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - 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.

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{
  "name": "sample-babel-helper-validator-identifier",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-babel-helper-validator-identifier",
      "version": "1.0.0",
      "license": "MIT-0",
      "dependencies": {
        "@babel/helper-validator-identifier": "8.0.4"
      }
    },
    "node_modules/@babel/helper-validator-identifier": {
      "version": "8.0.4",
      "resolved": "https://registry.npmjs.org/@babel/helper-validator-identifier/-/helper-validator-identifier-8.0.4.tgz",
      "integrity": "sha512-4wFaiLd0bVo4cIoTXI3zKI038NIWE/cr3jvBjejOVYVxV/m8Ltav1USiGzG1fmS5J2RhgEOgXNNK46cRPnRsrg==",
      "license": "MIT",
      "engines": {
        "node": "^22.18.0 || >=24.11.0"
      }
    }
  }
}

{
  "name": "sample-babel-helper-validator-identifier",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification of @babel/helper-validator-identifier.isReservedWord",
  "main": "src/index.js",
  "license": "MIT-0",
  "dependencies": {
    "@babel/helper-validator-identifier": "8.0.4"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify @babel/helper-validator-identifier.isReservedWord in pkg:npm/%40babel/helper-validator-identifier@8.0.4",
  "kind": "HOW",
  "packages": [
    "pkg:npm/%40babel/helper-validator-identifier@8.0.4"
  ],
  "symbols": [
    "@babel/helper-validator-identifier.isReservedWord"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "runtime": "node@22.23.2"
  }
}

const { isReservedWord } = require('@babel/helper-validator-identifier');

/**
 * Checks whether a given word is a JavaScript reserved word in the specified module context.
 * @param {string} word - The identifier string to check.
 * @param {boolean} [inModule=false] - Whether the context is inside an ES module.
 * @returns {boolean} True if the word is a reserved word.
 */
function checkIsReservedWord(word, inModule = false) {
  return isReservedWord(word, inModule);
}

/**
 * Filters a list of words and returns only those that are reserved words.
 * @param {string[]} words - Array of words to check.
 * @param {boolean} [inModule=false] - Whether the context is inside an ES module.
 * @returns {string[]} Array containing only reserved words.
 */
function filterReservedWords(words, inModule = false) {
  if (!Array.isArray(words)) {
    return [];
  }
  return words.filter((word) => typeof word === 'string' && isReservedWord(word, inModule));
}

module.exports = {
  checkIsReservedWord,
  filterReservedWords,
};

import assert from 'node:assert';
import { createRequire } from 'node:module';

const require = createRequire(import.meta.url);
const { checkIsReservedWord, filterReservedWords } = require('../src/index.js');
const { isReservedWord } = require('@babel/helper-validator-identifier');

async function runContract() {
  // 1. isReservedWord returns true for enum regardless of whether inModule is true or false
  assert.strictEqual(isReservedWord('enum', true), true, 'expected isReservedWord("enum", true) to be true');
  assert.strictEqual(isReservedWord('enum', false), true, 'expected isReservedWord("enum", false) to be true');
  assert.strictEqual(isReservedWord('enum'), true, 'expected isReservedWord("enum") to be true');
  assert.strictEqual(checkIsReservedWord('enum', true), true, 'expected wrapper checkIsReservedWord("enum", true) to be true');
  assert.strictEqual(checkIsReservedWord('enum', false), true, 'expected wrapper checkIsReservedWord("enum", false) to be true');
  assert.strictEqual(checkIsReservedWord('enum'), true, 'expected wrapper checkIsReservedWord("enum") to be true');

  // 2. isReservedWord returns true for await when inModule is true
  assert.strictEqual(isReservedWord('await', true), true, 'expected isReservedWord("await", true) to be true');
  assert.strictEqual(checkIsReservedWord('await', true), true, 'expected wrapper checkIsReservedWord("await", true) to be true');

  // 3. isReservedWord returns false for await when inModule is false or omitted
  assert.strictEqual(Boolean(isReservedWord('await', false)), false, 'expected isReservedWord("await", false) to be false');
  assert.strictEqual(Boolean(isReservedWord('await')), false, 'expected isReservedWord("await") to be false');
  assert.strictEqual(Boolean(checkIsReservedWord('await', false)), false, 'expected wrapper checkIsReservedWord("await", false) to be false');
  assert.strictEqual(Boolean(checkIsReservedWord('await')), false, 'expected wrapper checkIsReservedWord("await") to be false');

  // 4. isReservedWord returns false for regular identifier names and standard keywords when checking reserved word status
  const nonReservedWords = [
    'foo',
    'bar',
    'identifier',
    'myVar',
    'if',
    'while',
    'const',
    'let',
    'function',
    'class',
    'return',
    'import',
    'export',
  ];

  for (const word of nonReservedWords) {
    assert.strictEqual(Boolean(isReservedWord(word, true)), false, `expected isReservedWord("${word}", true) to be false`);
    assert.strictEqual(Boolean(isReservedWord(word, false)), false, `expected isReservedWord("${word}", false) to be false`);
    assert.strictEqual(Boolean(checkIsReservedWord(word, true)), false, `expected checkIsReservedWord("${word}", true) to be false`);
    assert.strictEqual(Boolean(checkIsReservedWord(word, false)), false, `expected checkIsReservedWord("${word}", false) to be false`);
  }

  // 5. isReservedWord returns false for uppercase or mixed-case variants of enum and await
  const casedVariants = [
    'ENUM',
    'Enum',
    'eNum',
    'AWAIT',
    'Await',
    'aWait',
  ];

  for (const word of casedVariants) {
    assert.strictEqual(Boolean(isReservedWord(word, true)), false, `expected cased variant "${word}" with inModule=true to return false`);
    assert.strictEqual(Boolean(isReservedWord(word, false)), false, `expected cased variant "${word}" with inModule=false to return false`);
    assert.strictEqual(Boolean(checkIsReservedWord(word, true)), false, `expected checkIsReservedWord("${word}", true) to return false`);
    assert.strictEqual(Boolean(checkIsReservedWord(word, false)), false, `expected checkIsReservedWord("${word}", false) to return false`);
  }

  // Helper validation: filterReservedWords
  const testList = ['foo', 'enum', 'bar', 'await', 'if', 'const'];
  const filteredModule = filterReservedWords(testList, true);
  assert.deepStrictEqual(filteredModule, ['enum', 'await']);

  const filteredScript = filterReservedWords(testList, false);
  assert.deepStrictEqual(filteredScript, ['enum']);

  assert.deepStrictEqual(filterReservedWords([]), []);
  assert.deepStrictEqual(filterReservedWords(null), []);

  console.log('Contract tests passed successfully.');
}

runContract().catch((err) => {
  console.error('Contract test failed:', err);
  process.exit(1);
});