public class updatecon{

 public id tobeEdited{get; set;}
list<contact> lstcontact = [SELECT ID,name, Firstname,lastname,email,phone from contact];

public void saveRecord(){
        Contact tobeupdated;
        for(Contact temp : lstcontact){
            if(temp.id==tobeEdited){
                tobeupdated = temp;
                break;
            }
        }
        update tobeupdated;
        tobeEdited = null;
    }
}

@istest
public class testupdatecon{
public static testMethod void testMyController(){
updatecon update = new updatecon();
update .saveRecord();
}
}