Tip! Mock jsdom location with Jest

Problem

In some cases, we have to call assign method of window.location object in order to redirect to a different url as below:

window.location.assign = '/home';

You would receive an warning like below in case of jest running through above code:

Error: Not implemented: navigation (except hash changes)

What is the solution here?

We obviously think about how to mock the location, right?

Here is the easiest way to do that:

const mockWinAssign = jest.fn();

const oldWindowLocation = window.location;

beforeAll(() => {
  delete window.location;
  window.location = Object.defineProperties(
    {},
    {
      ...Object.getOwnPropertyDescriptors(oldWindowLocation),
      assign: {
        configurable: true,
        value: mockWinAssign,
      },
    },
  )
})

afterAll(() => {
  // restore location
  window.location = oldWindowLocation;
})

test('your test to call location method', () => {
  // do things

  // finally
  expect(mockWinAssign).toHaveBeenCalledWith('/home');
})