unit testing - Assert that a method was called with an object that is changed in the method -

thats method want test:

public void set1(viewmodela viewmodela) {    var viewmodelb = new viewmodelb    {       firstname = viewmodela.firstname,       lastname = viewmodelb.lastname    }    service.set2(viewmodelb); } 

how can assert viewmodelb instance passed service.set2 has property values mapped viewmodela , set2 took viewmodelb parameter?

assuming you've mocked service instance, should able this:

service.assertwascalled(s => s.set2(   arg<viewmodelb>.matches(b =>     b.firstname == "thefirstname" && b.lastname == "thelastname"   ) )); 

essentially you're doing asserting set2 method called, , given viewmodelb instance first , last name match you're expecting.