src/__tests__/components/Header.spec.tsx
import * as React from 'react'
import { render } from '@testing-library/react'
import '@testing-library/jest-dom'
import Header from '../../components/Header'
import { testHeader } from './TestUtils'
test('should render Header correctly', () => {
const { container } = render(<Header />)
testHeader(container.querySelector('header#header'))
})