🧪 Add a shared utility to cache and test the received ResizeObserverCallback

Closes Hacker0x01#5466

Author: balajis-qb

src/test/test_utils.ts

@@ -123,16 +123,27 @@ export const safeQuerySelectorAll = <T extends HTMLElement = HTMLElement>(
   return elements;
 };
 
+let _resizeObserverCallbackFn: ResizeObserverCallback | null;
+
+export const getResizeObserverCallback = () => _resizeObserverCallbackFn;
+
 export const setupMockResizeObserver = () => {
   const mockObserve = jest.fn();
   const mockDisconnect = jest.fn();
   const mockUnobserve = jest.fn();
 
-  const ResizeObserverMock = jest.fn(() => ({
-    observe: mockObserve,
-    disconnect: mockDisconnect,
-    unobserve: jest.fn(),
-  }));
+  const ResizeObserverMock = jest.fn((fn) => {
+    _resizeObserverCallbackFn = fn;
+
+    return {
+      observe: mockObserve,
+      disconnect: () => {
+        _resizeObserverCallbackFn = null;
+        mockDisconnect();
+      },
+      unobserve: jest.fn(),
+    };
+  });
 
   global.ResizeObserver = ResizeObserverMock;
 

src/test/timepicker_test.test.tsx

@@ -6,6 +6,7 @@ import DatePicker from "../index";
 
 import {
   getKey,
+  getResizeObserverCallback,
   SafeElementWrapper,
   safeQuerySelector,
   safeQuerySelectorAll,
@@ -49,6 +50,14 @@ describe("TimePicker", () => {
       );
       await waitFor(() => {
         expect(mockObserve).toHaveBeenCalledTimes(1);
+
+        const resizeObserverCallback = getResizeObserverCallback();
+        const mockObserveElement = mockObserve.mock.calls[0][0];
+        expect(typeof resizeObserverCallback).toBe("function");
+
+        if (resizeObserverCallback) {
+          resizeObserverCallback([], mockObserveElement);
+        }
       });
     });
 
@@ -65,6 +74,8 @@ describe("TimePicker", () => {
       component.unmount();
       await waitFor(() => {
         expect(mockDisconnect).toHaveBeenCalledTimes(1);
+        const resizeObserverCallback = getResizeObserverCallback();
+        expect(resizeObserverCallback).toBe(null);
       });
     });
   });