example.js

// query utilities:
import {getByLabelText, getByText, getByTestId, queryByTestId, wait} from '../'
// adds special assertions like toHaveTextContent
import '../extend-expect'

function getExampleDOM() {
  // This is just a raw example of setting up some DOM
  // that we can interact with. Swap this with your UI
  // framework of choice 😉
  const div = document.createElement('div')
  div.innerHTML = `
    <label for="username">Username</label>
    <input id="username" />
    <button>Print Username</button>
  `
  const button = div.querySelector('button')
  const input = div.querySelector('input')
  button.addEventListener('click', () => {
    // let's pretend this is making a server request, so it's async
    // (you'd want to mock this imaginary request in your unit tests)...
    setTimeout(() => {
      const printedUsernameContainer = document.createElement('div')
      printedUsernameContainer.innerHTML = `
        <div data-testid="printed-username">${input.value}</div>
      `
      div.appendChild(printedUsernameContainer)
    }, Math.floor(Math.random() * 200))
  })
  return div
}

test('examples of some things', async () => {
  const famousWomanInHistory = 'Ada Lovelace'
  const container = getExampleDOM()

  // Get form elements by their label text.
  // An error will be thrown if one cannot be found (accessibility FTW!)
  const input = getByLabelText(container, 'Username')
  input.value = famousWomanInHistory

  // Get elements by their text, just like a real user does.
  getByText(container, 'Print Username').click()

  await wait(() =>
    expect(queryByTestId(container, 'printed-username')).toBeInTheDOM(),
  )

  // getByTestId and queryByTestId are an escape hatch to get elements
  // by a test id (could also attempt to get this element by it's text)
  expect(getByTestId(container, 'printed-username')).toHaveTextContent(
    famousWomanInHistory,
  )
  expect(container).toMatchSnapshot()
})