test: Update tests for ResizeObserver polyfill removal

src/app-layout/__tests__/main.test.tsx

@@ -1,6 +1,7 @@
 // Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
 // SPDX-License-Identifier: Apache-2.0
 import * as React from 'react';
+import { useLayoutEffect } from 'react';
 import { waitFor } from '@testing-library/react';
 
 import '../../__a11y__/to-validate-a11y';
@@ -11,6 +12,22 @@ import { describeEachAppLayout, renderComponent, testDrawer } from './utils';
 import mobileStyles from '../../../lib/components/app-layout/mobile-toolbar/styles.css.js';
 import sharedStyles from '../../../lib/components/app-layout/styles.css.js';
 
+jest.mock('@cloudscape-design/component-toolkit/internal', () => ({
+  ...jest.requireActual('@cloudscape-design/component-toolkit/internal'),
+  useResizeObserver: (getElement: any, onObserve: any) => {
+    useLayoutEffect(() => {
+      if (typeof getElement === 'function') {
+        const element = getElement();
+        if (element) {
+          // Extract height from inline styles for JSDOM compatibility
+          const height = parseInt(element.style.height) || 0;
+          onObserve({ borderBoxHeight: height });
+        }
+      }
+    }, [getElement, onObserve]);
+  },
+}));
+
 test('does not render mobile mode by default', () => {
   const { wrapper } = renderComponent(<AppLayout />);
   expect(wrapper.findByClassName(mobileStyles['mobile-bar'])).toBeFalsy();

src/table/__integ__/resizable-columns-misc.test.ts

@@ -89,11 +89,11 @@ test(
     await page.installObserver(wrapper.find('table').toSelector());
     await page.click('#shrink-container');
     await page.waitForJsTimers();
-    // expected 1 observation after creating observer and 1 caused by container shrink
-    await expect(page.getObservations()).resolves.toBe(2);
+    // check to ensure that we haven't triggered an infinite resize loop
+    await expect(page.getObservations()).resolves.toBeLessThanOrEqual(3);
     await page.waitForJsTimers();
-    // ensure there are no more observations added after the expected 2
-    await expect(page.getObservations()).resolves.toBe(2);
+    // check again to ensure that we haven't triggered an infinite resize loop
+    await expect(page.getObservations()).resolves.toBeLessThanOrEqual(3);
   })
 );