Mastering React Test-Driven Development

Changing location using history.push

Link components are one way to cause a URL change, but clearly, they require the user to click on them. To programmatically change a URL, we need to use the history prop that React Router gives us. This has a push function, which we can test using a standard spy.

In the test that follows, App is passed a history object, which replicates the object that a Router component would give us:

describe('App', () => {  let historySpy;  beforeEach(() => {    historySpy = jest.fn();  });  it('navigates to / when AppointmentFormLoader is saved', () => {    render(<App history={{ push: historySpy }} />);    const onSave = routeFor('/addAppointment').props.render().props.onSave;    onSave(); expect(historySpy).toHaveBeenCalledWith('/'); ...