chore: [#1510] Fixes failing integration test

packages/global-registrator/src/GlobalRegistrator.ts

@@ -80,7 +80,6 @@ export default class GlobalRegistrator {
 		}
 
 		// Set owner window on document to global
-		global.document[PropertySymbol.window] = global;
 		global.document[PropertySymbol.defaultView] = global;
 	}
 

packages/global-registrator/test/react/React.test.tsx

@@ -57,6 +57,17 @@ async function main(): Promise<void> {
 
 	testGetters();
 
+	/**
+	 * Test if Window properties are available on the global object.
+	 */
+	function testWindowProperties(): void {
+		if (!(globalThis.customElements instanceof globalThis.CustomElementRegistry)) {
+			throw Error('Expected globalThis.customElements to be an instance of CustomElementRegistry.');
+		}
+	}
+
+	testWindowProperties();
+
 	/**
 	 * Test if it is possible to create a React component and mount it.
 	 */

packages/happy-dom/src/window/BrowserWindow.ts

@@ -265,12 +265,12 @@ export default class BrowserWindow extends EventTarget implements INodeJSGlobal
 	public readonly Element = Element;
 	public readonly CharacterData = CharacterData;
 	public readonly DocumentType = DocumentType;
-	public readonly Document = Document;
-	public readonly HTMLDocument = HTMLDocument;
-	public readonly XMLDocument = XMLDocument;
-	public readonly SVGDocument = SVGDocument;
 
 	// Nodes that can be created using "new" keyword (populated by WindowClassExtender)
+	public declare readonly Document: typeof Document;
+	public declare readonly HTMLDocument: typeof HTMLDocument;
+	public declare readonly XMLDocument: typeof XMLDocument;
+	public declare readonly SVGDocument: typeof SVGDocument;
 	public declare readonly DocumentFragment: typeof DocumentFragment;
 	public declare readonly Text: typeof Text;
 	public declare readonly Comment: typeof Comment;
@@ -505,7 +505,7 @@ export default class BrowserWindow extends EventTarget implements INodeJSGlobal
 
 	// Public properties.
 	public readonly document: Document;
-	public readonly customElements: CustomElementRegistry;
+	public readonly customElements: CustomElementRegistry = new CustomElementRegistry(this);
 	public readonly window: BrowserWindow = this;
 	public readonly globalThis: BrowserWindow = this;
 	public readonly performance: typeof performance = performance;
@@ -619,7 +619,6 @@ export default class BrowserWindow extends EventTarget implements INodeJSGlobal
 
 		this.#browserFrame = browserFrame;
 
-		this.customElements = new CustomElementRegistry(this);
 		this.console = browserFrame.page.console;
 
 		this[PropertySymbol.navigator] = new Navigator(this);

packages/happy-dom/src/window/WindowClassExtender.ts

@@ -1,7 +1,6 @@
 import BrowserWindow from './BrowserWindow.js';
 import * as PropertySymbol from '../PropertySymbol.js';
 
-import ElementImplementation from '../nodes/element/Element.js';
 import DocumentImplementation from '../nodes/document/Document.js';
 import HTMLDocumentImplementation from '../nodes/html-document/HTMLDocument.js';
 import XMLDocumentImplementation from '../nodes/xml-document/XMLDocument.js';
@@ -64,11 +63,6 @@ export default class WindowClassExtender {
 	public static extendClass(window: BrowserWindow): void {
 		/* eslint-disable jsdoc/require-jsdoc */
 
-		// Element
-		class Element extends ElementImplementation {}
-		Element.prototype[PropertySymbol.window] = window;
-		(<typeof Element>window.Element) = Element;
-
 		// Document
 		class Document extends DocumentImplementation {}
 		Document.prototype[PropertySymbol.window] = window;