example-react-router.mdx

id	title
example-react-router	React Router

// app.js
import React from 'react'
import {Link, Route, Switch, useLocation} from 'react-router-dom'

const About = () => <div>You are on the about page</div>
const Home = () => <div>You are home</div>
const NoMatch = () => <div>No match</div>

export const LocationDisplay = () => {
  const location = useLocation()

  return <div data-testid="location-display">{location.pathname}</div>
}

export const App = () => (
  <div>
    <Link to="/">Home</Link>

    <Link to="/about">About</Link>

    <Switch>
      <Route exact path="/">
        <Home />
      </Route>

      <Route path="/about">
        <About />
      </Route>

      <Route>
        <NoMatch />
      </Route>
    </Switch>

    <LocationDisplay />
  </div>
)

// app.test.js
import {render, screen} from '@testing-library/react'
import userEvent from '@testing-library/user-event'
import {createMemoryHistory} from 'history'
import React from 'react'
import {Router} from 'react-router-dom'

import '@testing-library/jest-dom'

import {App, LocationDisplay} from './app'

test('full app rendering/navigating', () => {
  const history = createMemoryHistory()
  render(
    <Router history={history}>
      <App />
    </Router>,
  )
  // verify page content for expected route
  // often you'd use a data-testid or role query, but this is also possible
  expect(screen.getByText(/you are home/i)).toBeInTheDocument()

  const leftClick = {button: 0}
  userEvent.click(screen.getByText(/about/i), leftClick)

  // check that the content changed to the new page
  expect(screen.getByText(/you are on the about page/i)).toBeInTheDocument()
})

test('landing on a bad page', () => {
  const history = createMemoryHistory()
  history.push('/some/bad/route')
  render(
    <Router history={history}>
      <App />
    </Router>,
  )

  expect(screen.getByText(/no match/i)).toBeInTheDocument()
})

test('rendering a component that uses useLocation', () => {
  const history = createMemoryHistory()
  const route = '/some-route'
  history.push(route)
  render(
    <Router history={history}>
      <LocationDisplay />
    </Router>,
  )

  expect(screen.getByTestId('location-display')).toHaveTextContent(route)
})

Reducing boilerplate

1. You can use the wrapper option to wrap a MemoryRouter around the component you want to render.
   MemoryRouter works when you don't need access to the history object itself in the test, but just need the components to be able to render and navigate.
   If you do need to change the history, you could use BrowserRouter.

import {MemoryRouter} from 'react-router-dom'

test('full app rendering/navigating', () => {
  render(<App />, {wrapper: MemoryRouter})

  // verify page content for expected route
  expect(screen.getByText(/you are home/i)).toBeInTheDocument()
})

2. If you find yourself adding Router components to your tests a lot, you may want to create a helper function that wraps around render.

// test utils file
const renderWithRouter = (ui, {route = '/'} = {}) => {
  window.history.pushState({}, 'Test page', route)

  return render(ui, {wrapper: BrowserRouter})
}

// app.test.js
test('full app rendering/navigating', () => {
  renderWithRouter(<App />)
  expect(screen.getByText(/you are home/i)).toBeInTheDocument()

  const leftClick = {button: 0}
  userEvent.click(screen.getByText(/about/i), leftClick)

  expect(screen.getByText(/you are on the about page/i)).toBeInTheDocument()
})

test('landing on a bad page', () => {
  renderWithRouter(<App />, {route: '/something-that-does-not-match'})

  expect(screen.getByText(/no match/i)).toBeInTheDocument()
})

test('rendering a component that uses useLocation', () => {
  const route = '/some-route'
  renderWithRouter(<LocationDisplay />, {route})

  expect(screen.getByTestId('location-display')).toHaveTextContent(route)
})