Mastering React Test-Driven Development

Testing the default route

A Switch component lists a number of routes, only one of which will be rendered at a time. The last Route listed in a Switch will be the one used if nothing else matches, just as a switch statement in most programming languages makes the last clause its default clause.

Here's a test to verify that the last route renders what we expect. The name of the test is important; it explicitly mentions that this is the default route:

it('renders the MainScreen as the default route', () => {  render(<App />);  const routes = childRoutes();  const lastRoute = routes[routes.length - 1];  expect(lastRoute.props.component).toEqual(MainScreen);});

The test succinctly encodes the notion of a default route into our tests, which is useful ...