combineLatest with marble syntax

Question

So I faced a problem when trying to test combineLatest result I am facing an error.

        const e1 = hot('^--a--|');
        const e2 = hot('^---b-|');
   
        const expected = cold('--(ab)-|');

        expect(combineLatest([e1, e2])).toBeObservable(expected);

I am not sure about expected value, I know that combineLatest will return [a,b] but don't know how to write it properly, any clues?