c# - IndexOf find no element in a List<> while Mock -

i have list of object below

public class person {    public string name {get; set;}    public int age {get; set;} } public class someclass { public int dosomething () {     int result;     list<person> personlist = new list<person>();     personlist.add(new person { //with 1 object, keep simple        name = "someone",        age = 18});    person eighteenyearsold = _checkage.findeighteenyearsold (personlist);    int index = personlist.indexof (eighteenyearsold);    //do    return result; } } [testmethod] public void dosomething_test() {     //given:      //when: call someclass object     person eightnneyears = new person {        name = "someone",        age = 18};    _mockcheckage.setup (x => x.findeighteenyearsold(it.isany<list<person>>())).returns(eightnneyears);    _someclass = new someclass (_mockcheckage.object);    int result = _someclass.dosomething();    //then:  } 

as have mocked findeighteenyearsold method returns person object same states presents in personlist. when personlist.indexof() executes returns index -1, suppose 0. should do.

list.indexof uses equals find equal objects. if class doesn't override references compared. since 2 instances not same list.indexof returns -1.

so override equals (and gethashcode then):

public class person {     public string name { get; set; }     public int age { get; set; }      public override bool equals (object obj)     {         person otherperson = obj person;         return otherperson != null              && otherperson.name == name              && otherperson.age == age;     }      // http://stackoverflow.com/a/263416/284240     public override int gethashcode()     {         unchecked // overflow fine, wrap         {             int hash = 17;             hash = hash * 23 + (name?.gethashcode() ?? 0); // or: hash = hash * 23 + (name == null ? 0 : name.gethashcode());             hash = hash * 23 + age; ;             return hash;         }     } }