Jasmine spyOn lodash方法＆＃39; set＆＃39;

Question

我在代码中使用set。它是这样使用的

import * as set from 'lodash/set';

................

  @Effect({ dispatch: false })
  redirectWithHref$: Observable<void> = this.actions$.pipe(
    ofType<ActionWithPayload>(REDIRECT_TO_EXTERNAL),
    map(action => action.payload),
    tap(url => set(window.location, 'href', url))
  );

................

我正在尝试spyOn使用Jasmine，但它没有其他方法，当我试图窥探它抱怨它找不到要监视的对象时。

 ​​​​AuthEffects redirectWithHref should call set on the window with the payload as the url​​​​ ​​​[74 ms]​​​​
    ​​​​
    ​​Failed: <spyOn> : could not find an object to spy upon for default()​​
    ​​Usage: spyOn(<object>, <methodName>)​​
      at t.<anonymous> ​src/app/store/auth/auth.effects.spec.ts:111:6​

我的测试看起来像......

 describe('redirectWithHref', () => {
    fit('should call set on the window with the payload as the url', async(() => {
      const { effects, actions } = setup({});
      const setSpy = spyOn(set, 'default');
      actions.next({ type: REDIRECT_TO_EXTERNAL, payload: 'http://foo.bar' });

      expect(setSpy).toHaveBeenCalledWith('http://foo.bar');
    }));
  });

我怎么能窥探这个？使用Angular 6 w / NgRX 6