Use createRoot in ReactMockedComponent-test (#28087)

Co-authored-by: Jack Pope <jackpope@meta.com>

packages/react-dom/src/__tests__/ReactMockedComponent-test.js

@@ -10,16 +10,18 @@
 'use strict';
 
 let React;
-let ReactDOM;
+let ReactDOMClient;
+let act;
 
 let MockedComponent;
 let ReactDOMServer;
 
 describe('ReactMockedComponent', () => {
  beforeEach(() => {
  React = require('react');
- ReactDOM = require('react-dom');
+ ReactDOMClient = require('react-dom/client');
  ReactDOMServer = require('react-dom/server');
+ act = require('internal-test-utils').act;
 
  MockedComponent = class extends React.Component {
  render() {
@@ -30,15 +32,23 @@ describe('ReactMockedComponent', () => {
  MockedComponent.prototype.render = jest.fn();
  });
 
- it('should allow a mocked component to be rendered', () => {
+ it('should allow a mocked component to be rendered', async () => {
  const container = document.createElement('container');
- ReactDOM.render(<MockedComponent />, container);
+ const root = ReactDOMClient.createRoot(container);
+ await act(() => {
+ root.render(<MockedComponent />);
+ });
  });
 
- it('should allow a mocked component to be updated in dev', () => {
+ it('should allow a mocked component to be updated in dev', async () => {
  const container = document.createElement('container');
- ReactDOM.render(<MockedComponent />, container);
- ReactDOM.render(<MockedComponent />, container);
+ const root = ReactDOMClient.createRoot(container);
+ await act(() => {
+ root.render(<MockedComponent />);
+ });
+ await act(() => {
+ root.render(<MockedComponent />);
+ });
  });
 
  it('should allow a mocked component to be rendered in dev (SSR)', () => {