Convert ReactJSXElementValidator to createRoot (#28209)

packages/react/src/__tests__/ReactJSXElementValidator-test.js

@@ -13,8 +13,10 @@
 // of dynamic errors when using JSX with Flow.
 let React;
 let ReactDOM;
+let ReactDOMClient;
 let ReactTestUtils;
 let PropTypes;
+let act;
 
 describe('ReactJSXElementValidator', () => {
   let Component;
@@ -26,7 +28,9 @@ describe('ReactJSXElementValidator', () => {
     PropTypes = require('prop-types');
     React = require('react');
     ReactDOM = require('react-dom');
+    ReactDOMClient = require('react-dom/client');
     ReactTestUtils = require('react-dom/test-utils');
+    act = require('internal-test-utils').act;
 
     Component = class extends React.Component {
       render() {
@@ -172,7 +176,7 @@ describe('ReactJSXElementValidator', () => {
     );
   });
 
-  it('should update component stack after receiving next element', () => {
+  it('should update component stack after receiving next element', async () => {
     function MyComp() {
       return null;
     }
@@ -192,9 +196,14 @@ describe('ReactJSXElementValidator', () => {
     }
 
     const container = document.createElement('div');
-    ReactDOM.render(<ParentComp warn={false} />, container);
+    const root = ReactDOMClient.createRoot(container);
+    await act(() => {
+      root.render(<ParentComp warn={false} />);
+    });
     expect(() =>
-      ReactDOM.render(<ParentComp warn={true} />, container),
+      ReactDOM.flushSync(() => {
+        root.render(<ParentComp warn={true} />);
+      }),
     ).toErrorDev(
       'Warning: Failed prop type: ' +
         'Invalid prop `color` of type `number` supplied to `MyComp`, ' +