static void Main(string[] args) { File.Delete("Department.xml"); File.Delete("Employee.xml"); IRepository repo = new XmlRepository(); Populate(repo); var employees = repo.Employees; PrintEmployees(employees); var emplArtur = repo.Employees.First( e => e.FirstName.Equals("Artur", StringComparison.InvariantCultureIgnoreCase) ); emplArtur.Promote(); repo.Save(); PrintEmployees(repo.Employees); var engeneeringDepartment = new Department { Id = 4, Name = "Engineering" }; repo.AddDepartment(engeneeringDepartment); repo.Save(); PrintDepartments(repo.Departments); emplArtur.ChangeDepartment(engeneeringDepartment); repo.Save(); PrintEmployees(repo.Employees); emplArtur.Demote(); repo.Save(); PrintEmployees(repo.Employees); var marcoCantu = employees.Single(e => e.FirstName.Equals("Marco") && e.SecondName.Equals("Cantu")); emplArtur.ChangeChief(marcoCantu); repo.Save(); PrintEmployees(repo.Employees); Console.Read(); }