Jest.js force window to be undefined

Question

I'm working with jest + enzyme setup for tests. I have function that conditionally renders something if window is defined.

In my test suite I'm trying to reach second case, when window is not defined, but I can't force it.

    it('makes something when window is not defined', () => {
       window = undefined;
       expect(myFunction()).toEqual(thisWhatIWantOnUndefinedWinow);
    });

But even if I force window to be undefined, it doesn't reach expected case, window is always window (jsdom?)

Is it something with my jest setup or I should handle this another way?

Answer 1

I am able to test the scenario where window is undefined using the below pattern. It allows you to run tests with and without window in the same file. Adding @jest-environment node at the top of the file is not required.

describe('when window is undefined', () => {
    const { window } = global;
    beforeAll(() => {
      // @ts-ignore
      delete global.window;
    });
    afterAll(() => {
      global.window = window;
    });
    
    it('runs without error', () => {
      ...
    });
});