static public string ValidationMessageFor(LoginValidationExceptions exception)
        {
            var message = "Unknown exception!";

            switch (exception)
            {
            case LoginValidationExceptions.InvalidUsername:
                message = "Invalid username. Username cannot be empty.";
                break;

            case LoginValidationExceptions.InvalidPassword:
                message = "Invalid password. Password cannot be empty";
                break;
            }

            return(message);
        }
 static public LoginValidationException CreateException(LoginValidationExceptions exception)
 {
     return(new LoginValidationException(LoginValidationException.ValidationMessageFor(exception)));
 }