React Snapshot Testing

App.test.js

import React from 'react'
import renderer from 'react-test-renderer'
import shallowRenderer from 'react-test-renderer/shallow'
import App from './App'

describe('Test app component', () => {
  it('shallow snapshot', () => {
    const renderer = new shallowRenderer
    const snapshot = renderer.render(<App />)
    expect(snapshot).toMatchSnapshot()
  })

  it('full snapshot', () => {
    const html = renderer.create(<App />).toJSON()
    expect(html).toMatchSnapshot()
  })
})