How to spy on window resize event in test.

spy-resize-event.test.js

const spy = jest.fn(); // or `jasmine.createSpy()`
const testWidth = 420;

beforeAll(() => {
  window.addEventListener('resize', spy);
});

it('does not fire resize event by default', () => {
  expect(spy).not.toHaveBeenCalled();
  expect(window.innerWidth).not.toBe(testWidth);
});

describe('when resize event is fired', () => {
  beforeAll(() => {
    window.innerWidth = testWidth;
    window.dispatchEvent(new Event('resize'));
    // const resizeEvent = document.createEvent('Event');
    // resizeEvent.initEvent('resize', true, true);
    // window.dispatchEvent(resizeEvent);
  });

  it('updates the window width', () => {
    expect(spy).toHaveBeenCalled();
    expect(window.innerWidth).toBe(testWidth);
  });
});

What did you mean on strings 17-19?