react-is 17.0.2: ForwardRef

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 react-is.ForwardRef in pkg:npm/react-is@17.0.2
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/react-is@17.0.2
Demonstrate these symbols/APIs:
  - react-is.ForwardRef
Constraints:
  - executionContext: node
Required runtime conditions:
  - ecosystem: npm
  - language: javascript
  - moduleSystem: cjs
  - packageManager: npm@10.9.8
  - 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.

{"case":{"caseId":"case:sha256:69367b5549dcf1f40e4389453f9008af2391dbcbfce091c3338f957c32c0a331","constraints":{"executionContext":"node"},"contract":["ForwardRef is exported as a symbol equal to Symbol.for('react.forward_ref')","isForwardRef correctly identifies React 17 forwardRef elements","typeOf returns ForwardRef symbol for forwardRef elements","isValidElementType returns true for forwardRef component","isForwardRef rejects standard HTML elements, fragment elements, and context elements","isForwardRef rejects non-element values, plain objects, raw forwardRef components, and primitives"],"goal":"verify react-is.ForwardRef in pkg:npm/react-is@17.0.2","kind":"HOW","packages":["pkg:npm/react-is@17.0.2"],"schemaVersion":1,"symbols":["react-is.ForwardRef"]},"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/react-is@17.0.2"],"schemaVersion":1,"subject":"pkg:npm/react-is@17.0.2","symbols":["react-is.ForwardRef"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-react-is-forward-ref",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-react-is-forward-ref",
      "version": "1.0.0",
      "dependencies": {
        "react-is": "17.0.2"
      }
    },
    "node_modules/react-is": {
      "version": "17.0.2",
      "resolved": "https://registry.npmjs.org/react-is/-/react-is-17.0.2.tgz",
      "integrity": "sha512-w2GsyukL62IJnlaff/nRegPQR94C/XXamvMWmSHRJ4y7Ts/4ocGRmTHvOs8PSE6pB3dWOrD/nueuU5sduBsQ4w==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-react-is-forward-ref",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification of react-is ForwardRef in React 17",
  "type": "module",
  "main": "src/index.js",
  "dependencies": {
    "react-is": "17.0.2"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify react-is.ForwardRef in pkg:npm/react-is@17.0.2",
  "kind": "HOW",
  "packages": [
    "pkg:npm/react-is@17.0.2"
  ],
  "symbols": [
    "react-is.ForwardRef"
  ],
  "constraints": {
    "executionContext": "node"
  },
  "runtimeConditions": {
    "ecosystem": "npm",
    "language": "javascript",
    "moduleSystem": "cjs",
    "packageManager": "npm@10.9.8",
    "runtime": "node@22.23.2"
  }
}

import {
  ForwardRef,
  isForwardRef,
  isValidElementType,
  typeOf,
} from 'react-is';

/**
 * Return the ForwardRef symbol from react-is.
 * In React 17, this corresponds to Symbol.for('react.forward_ref').
 *
 * @returns {symbol} The ForwardRef symbol.
 */
export function getForwardRefSymbol() {
  return ForwardRef;
}

/**
 * Check if the given element is a React ForwardRef element.
 *
 * @param {*} value - The value to inspect.
 * @returns {boolean} True if the value is a ForwardRef element.
 */
export function checkIsForwardRef(value) {
  return isForwardRef(value);
}

/**
 * Check if the given component type is a valid element type.
 *
 * @param {*} type - The component type to check.
 * @returns {boolean} True if the type is a valid element type.
 */
export function checkIsValidElementType(type) {
  return isValidElementType(type);
}

/**
 * Determine the element type symbol of a given React element using typeOf.
 *
 * @param {*} value - The React element to inspect.
 * @returns {symbol|undefined} The matched React symbol or undefined for non-elements.
 */
export function identifyElementType(value) {
  return typeOf(value);
}

/**
 * Helper to construct a synthetic React 17 ForwardRef component.
 *
 * @param {Function} [renderFn] - Render function for forwardRef component.
 * @returns {object} Synthetic forwardRef component.
 */
export function createSyntheticForwardRefComponent(renderFn = (props, ref) => null) {
  return {
    $$typeof: ForwardRef,
    render: renderFn,
  };
}

/**
 * Helper to construct a synthetic React 17 ForwardRef element.
 *
 * @param {object} forwardRefType - Component with $$typeof matching ForwardRef.
 * @param {object} [props={}] - Element props.
 * @returns {object} Synthetic React 17 element.
 */
export function createSyntheticForwardRefElement(forwardRefType, props = {}) {
  return {
    $$typeof: Symbol.for('react.element'),
    type: forwardRefType,
    props,
    key: null,
    ref: null,
  };
}

export {
  ForwardRef,
  isForwardRef,
  isValidElementType,
  typeOf,
};

import assert from 'node:assert/strict';
import {
  ForwardRef,
  isForwardRef,
  isValidElementType,
  typeOf,
  getForwardRefSymbol,
  checkIsForwardRef,
  checkIsValidElementType,
  identifyElementType,
  createSyntheticForwardRefComponent,
  createSyntheticForwardRefElement,
} from '../src/index.js';

// 1. ForwardRef symbol export verification
assert.equal(typeof ForwardRef, 'symbol', 'ForwardRef must be exported as a symbol');
assert.equal(
  ForwardRef,
  Symbol.for('react.forward_ref'),
  'ForwardRef in React 17 must match Symbol.for("react.forward_ref")'
);
assert.equal(
  getForwardRefSymbol(),
  ForwardRef,
  'getForwardRefSymbol helper must return ForwardRef symbol'
);

// 2. isForwardRef function export verification
assert.equal(typeof isForwardRef, 'function', 'isForwardRef must be exported as a function');
assert.equal(typeof checkIsForwardRef, 'function', 'checkIsForwardRef helper must be a function');

// 3. isValidElementType verification for forwardRef component
const forwardRefComponent = createSyntheticForwardRefComponent();
assert.equal(
  isValidElementType(forwardRefComponent),
  true,
  'isValidElementType must return true for forwardRef component'
);
assert.equal(
  checkIsValidElementType(forwardRefComponent),
  true,
  'checkIsValidElementType helper must return true for forwardRef component'
);

// 4. React 17 forwardRef element identification
const forwardRefElement = createSyntheticForwardRefElement(forwardRefComponent, {
  label: 'contract-test-label',
});

assert.equal(
  isForwardRef(forwardRefElement),
  true,
  'isForwardRef must return true for React 17 forwardRef elements'
);
assert.equal(
  checkIsForwardRef(forwardRefElement),
  true,
  'checkIsForwardRef helper must return true for React 17 forwardRef elements'
);
assert.equal(
  typeOf(forwardRefElement),
  ForwardRef,
  'typeOf must return ForwardRef symbol for forwardRef elements'
);
assert.equal(
  identifyElementType(forwardRefElement),
  ForwardRef,
  'identifyElementType helper must return ForwardRef symbol'
);

// 5. Distinction from standard elements and other component types
const standardElement = {
  $$typeof: Symbol.for('react.element'),
  type: 'button',
  props: { className: 'btn' },
  key: null,
  ref: null,
};
assert.equal(
  isForwardRef(standardElement),
  false,
  'isForwardRef must return false for standard HTML/DOM elements'
);
assert.notEqual(
  typeOf(standardElement),
  ForwardRef,
  'typeOf on standard elements must not equal ForwardRef'
);

const fragmentElement = {
  $$typeof: Symbol.for('react.element'),
  type: Symbol.for('react.fragment'),
  props: {},
  key: null,
  ref: null,
};
assert.equal(
  isForwardRef(fragmentElement),
  false,
  'isForwardRef must return false for fragment elements'
);

const providerElement = {
  $$typeof: Symbol.for('react.element'),
  type: {
    $$typeof: Symbol.for('react.provider'),
  },
  props: { value: 'context-val' },
  key: null,
  ref: null,
};
assert.equal(
  isForwardRef(providerElement),
  false,
  'isForwardRef must return false for context provider elements'
);

// 6. Non-element and invalid input rejection
assert.equal(isForwardRef(null), false, 'null is not a forwardRef element');
assert.equal(isForwardRef(undefined), false, 'undefined is not a forwardRef element');
assert.equal(isForwardRef({}), false, 'plain empty object is not a forwardRef element');
assert.equal(isForwardRef('react.forward_ref'), false, 'string primitive is not a forwardRef element');
assert.equal(isForwardRef(12345), false, 'number primitive is not a forwardRef element');
assert.equal(
  isForwardRef(forwardRefComponent),
  false,
  'raw forwardRef component object without element wrapper is not a forwardRef element'
);

assert.equal(typeOf(null), undefined, 'typeOf(null) must return undefined');
assert.equal(typeOf(undefined), undefined, 'typeOf(undefined) must return undefined');
assert.equal(typeOf({}), undefined, 'typeOf({}) must return undefined');
assert.equal(typeOf(forwardRefComponent), undefined, 'typeOf(forwardRefComponent) must return undefined');

console.log('All react-is.ForwardRef contract checks passed successfully.');