Desktop: Add new beta Markdown editor based on CodeMirror 6 (#8793)

packages/editor/jest.setup.js

@@ -0,0 +1,16 @@
+
+// Prevents the CodeMirror error "getClientRects is undefined".
+// See https://github.com/jsdom/jsdom/issues/3002#issue-652790925
+document.createRange = () => {
+	const range = new Range();
+	range.getBoundingClientRect = jest.fn();
+	range.getClientRects = () => {
+		return {
+			length: 0,
+			item: () => null,
+			[Symbol.iterator]: jest.fn(),
+		};
+	};
+
+	return range;
+};