Bug 940647 - Move bookmark creation to operator variant app

Is there any reason why you can't use something like:
 var browserSpy = this.sinon.spy(browserCustomizer, 'set');

and then on the tests use something like:
 assert.isTrue(browserSpy.calledWith({ /* object that you expect to have been passed */});

If you can do it in this way, you wouldn't need to add extra parameters to the code only for the unit tests.