namae/src/App.test.tsx

import { render } from '@testing-library/react'
import 'mutationobserver-shim'
import React, { Suspense } from 'react'
import { BrowserRouter as Router } from 'react-router-dom'
import App from './App'

it('renders welcome message', async () => {
  const { findByText } = render(
    <Suspense fallback={<div>loading</div>}>
      <Router>
        <App />
      </Router>
    </Suspense>
  )
  const text = await findByText('Grab a slick name for your new app')
  expect(text).toBeTruthy()
})