global.fetch = jest.fn();
const mockFetch = global.fetch as jest.Mock;

const iphoneHandlerRef = { current: false };
 mockFetch.mockImplementation((url, init) => {
 // Use the endpoint handlers approach
 const endpointHandlers = getEndpointHandlers(iphoneHandlerRef.current);
 const handler = endpointHandlers.find((h) =>
 h.match(url.toString(), init),
 );
 return Promise.resolve(
 handler ? handler.response() : mockResponses.default,
 );
 });
 const user = userEvent.setup();
 const { rerender, unmount } = render(<MockFlipSetup />);
 ...
 jest.restoreAllMocks();
 jest.clearAllMocks();
 iphoneHandlerRef.current = true;
 mockFetch.mockImplementation((url, init) => {
 // Use the endpoint handlers approach
 const endpointHandlers = getEndpointHandlers(iphoneHandlerRef.current);
 const handler = endpointHandlers.find((h) =>
 h.match(url.toString(), init),
 );
 return Promise.resolve(
 handler ? handler.response() : mockResponses.default,
 );
 });
 // Advance timers
 await act(() => {
 unmount();
 });
 // Rerender the component
 rerender(<MockFlipSetup />);