public void AddPermission_Owner_ShouldFail()
 {
     Assert.Throws <PermissionException>(() => OwnerCert.AddPermission(Permission.INVENTORY));
 }
 public void AddPermission_Manager_NewPermission_ShouldPass()
 {
     Assert.DoesNotThrow(() => ManagerCert.AddPermission(Permission.INVENTORY));
 }