public class UpdateAccountAddresses {
    Map<id,account>updateShippingAddressMap =new Map<id,Account>{};
    Map<id,Account> updateBillingAddressMap =new Map<id,Account>();
    set<id>AccountSetId=new Set<Id>{};
    list<contact> conlist=new list<contact>();

    public void RunOnUpdate(map<id,Account>NewMap,Map<id,Account>OldMap){
        for(id aid:newmap.keySet()){
            AccountSetId.add(aid);
            account newAccount=(Account)newmap.get(aid);
            account OldAccount=(Account)oldmap.get(aid);
            if(newAccount.ShippingCountry!=oldAccount.ShippingCountry ||
               newaccount.ShippingCity!=oldAccount.ShippingCity )
            {
                contact con=new contact(lastname='testforAcc',accountid=aid);
                conList.add(con);
            }
        }
        insert conlist;
    }
}

@isTest
public class UpdateAccountAddresses_Test {

    static  testmethod void runTest(){
            Account acc=new Account(name='testAccount',ShippingCity='Delhi',ShippingCountry='India');
            insert acc;
          acc.ShippingCity='jaypur';
            update acc;
        }
    }