import React from 'react' import { render, screen } from '@testing-library/react' import App from './App' let listener: ((rect: any) => void) | undefined = undefined ;(global as any).ResizeObserver = class ResizeObserver { constructor(ls: ((rect: any) => void) | undefined) { listener = ls } observe() {} unobserve() {} disconnect() {} } test('renders learn react link', () => { render() const linkElement = screen.getByText(/viewer/i) expect(linkElement).toBeInTheDocument() })