react-is 19.2.8: ContextProvider

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.ContextProvider in pkg:npm/react-is@19.2.8
Kind: HOW

Use EXACTLY these public packages and versions:
  - pkg:npm/react-is@19.2.8
Demonstrate these symbols/APIs:
  - react-is.ContextProvider

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:ddd5a1ff3a2c57a9503ae3ca138f8cbac4acfdb1dc787d0c1afff56d93456a76","constraints":{"executionContext":"node"},"contract":["ContextProvider is exported as a symbol equal to Symbol.for('react.context')","isContextProvider correctly identifies React 19 context provider elements","typeOf returns ContextProvider symbol for context provider elements","isContextProvider rejects standard HTML elements, fragment elements, and consumer elements","isContextProvider rejects non-element values, plain objects, raw context objects, and primitives"],"goal":"verify react-is.ContextProvider in pkg:npm/react-is@19.2.8","kind":"HOW","packages":["pkg:npm/react-is@19.2.8"],"schemaVersion":1,"symbols":["react-is.ContextProvider"]},"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@19.2.8"],"schemaVersion":1,"subject":"pkg:npm/react-is@19.2.8","symbols":["react-is.ContextProvider"],"verifierAdapter":"node-typescript@1"}

{
  "name": "sample-react-is-context-provider",
  "version": "1.0.0",
  "lockfileVersion": 3,
  "requires": true,
  "packages": {
    "": {
      "name": "sample-react-is-context-provider",
      "version": "1.0.0",
      "dependencies": {
        "react-is": "19.2.8"
      }
    },
    "node_modules/react-is": {
      "version": "19.2.8",
      "resolved": "https://registry.npmjs.org/react-is/-/react-is-19.2.8.tgz",
      "integrity": "sha512-s5un28nYxKJw5gvUHyW5PCC28CvBqLu9r3cWgzHT4Vo/5fqqkFcdRYsGcKf50WMPpjjFZS5d76fn3YCo2njKwQ==",
      "license": "MIT"
    }
  }
}

{
  "name": "sample-react-is-context-provider",
  "version": "1.0.0",
  "private": true,
  "description": "Clean-room verification of react-is ContextProvider in React 19",
  "type": "module",
  "main": "src/index.js",
  "dependencies": {
    "react-is": "19.2.8"
  }
}

{
  "schemaVersion": 1,
  "goal": "verify react-is.ContextProvider in pkg:npm/react-is@19.2.8",
  "kind": "HOW",
  "packages": [
    "pkg:npm/react-is@19.2.8"
  ],
  "symbols": [
    "react-is.ContextProvider"
  ]
}

import {
  ContextProvider,
  isContextProvider,
  typeOf,
} from 'react-is';

/**
 * Return the ContextProvider symbol from react-is.
 * In React 19, this corresponds to Symbol.for('react.context').
 *
 * @returns {symbol} The ContextProvider symbol.
 */
export function getContextProviderSymbol() {
  return ContextProvider;
}

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

/**
 * 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 19 Context Provider element.
 *
 * @param {*} contextType - The context object with $$typeof matching ContextProvider.
 * @param {object} [props={}] - Element props.
 * @returns {object} Synthetic React 19 element.
 */
export function createSyntheticProviderElement(contextType, props = {}) {
  return {
    $$typeof: Symbol.for('react.transitional.element'),
    type: contextType,
    props,
    key: null,
    ref: null,
  };
}

export {
  ContextProvider,
  isContextProvider,
  typeOf,
};

import assert from 'node:assert/strict';
import {
  ContextProvider,
  isContextProvider,
  typeOf,
  getContextProviderSymbol,
  checkIsContextProvider,
  identifyElementType,
  createSyntheticProviderElement,
} from '../src/index.js';

// 1. ContextProvider symbol export verification
assert.equal(typeof ContextProvider, 'symbol', 'ContextProvider must be exported as a symbol');
assert.equal(
  ContextProvider,
  Symbol.for('react.context'),
  'ContextProvider in React 19 must match Symbol.for("react.context")'
);
assert.equal(
  getContextProviderSymbol(),
  ContextProvider,
  'getContextProviderSymbol helper must return ContextProvider symbol'
);

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

// 3. React 19 context provider element identification
const contextObject = {
  $$typeof: ContextProvider,
  _currentValue: 'default-test-value',
};

const providerElement = createSyntheticProviderElement(contextObject, {
  value: 'custom-provider-value',
});

assert.equal(
  isContextProvider(providerElement),
  true,
  'isContextProvider must return true for React 19 context provider elements'
);
assert.equal(
  checkIsContextProvider(providerElement),
  true,
  'checkIsContextProvider helper must return true for React 19 context provider elements'
);
assert.equal(
  typeOf(providerElement),
  ContextProvider,
  'typeOf must return ContextProvider symbol for context provider elements'
);
assert.equal(
  identifyElementType(providerElement),
  ContextProvider,
  'identifyElementType helper must return ContextProvider symbol'
);

// 4. Distinction from standard elements and other component types
const standardElement = {
  $$typeof: Symbol.for('react.transitional.element'),
  type: 'div',
  props: { className: 'test-class' },
  key: null,
  ref: null,
};
assert.equal(
  isContextProvider(standardElement),
  false,
  'isContextProvider must return false for standard HTML/DOM elements'
);
assert.notEqual(
  typeOf(standardElement),
  ContextProvider,
  'typeOf on standard elements must not equal ContextProvider'
);

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

const consumerElement = {
  $$typeof: Symbol.for('react.transitional.element'),
  type: {
    $$typeof: Symbol.for('react.consumer'),
  },
  props: {},
  key: null,
  ref: null,
};
assert.equal(
  isContextProvider(consumerElement),
  false,
  'isContextProvider must return false for context consumer elements'
);

// 5. Non-element and invalid input rejection
assert.equal(isContextProvider(null), false, 'null is not a context provider');
assert.equal(isContextProvider(undefined), false, 'undefined is not a context provider');
assert.equal(isContextProvider({}), false, 'plain empty object is not a context provider');
assert.equal(isContextProvider('react.context'), false, 'string primitive is not a context provider');
assert.equal(isContextProvider(12345), false, 'number primitive is not a context provider');
assert.equal(isContextProvider(contextObject), false, 'raw context definition object without element wrapper is not a provider 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');

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