In your spec file import the helper this way:
import * as helper from './helper';
And in your it() you can spy on the helper object and return the requested value:
spyOn(helper, 'doSomething').and.returnValue({});
In your spec file import the helper this way:
import * as helper from './helper';
And in your it() you can spy on the helper object and return the requested value:
spyOn(helper, 'doSomething').and.returnValue({});