public void TestFailOnMissingReturnUrl()
        {
            const string expectedMessage = "MISSING VALUE - Return url is required, SetReturnUrl(...).\n";

            var exception = Assert.Throws<SveaWebPayValidationException>(() =>
                {
                    CreateOrderBuilder order = WebpayConnection.CreateOrder(SveaConfig.GetDefaultConfig())
                                                               .SetCountryCode(TestingTool.DefaultTestCountryCode)
                                                               .SetClientOrderNumber(TestingTool.DefaultTestClientOrderNumber)
                                                               .SetCurrency(TestingTool.DefaultTestCurrency)
                                                               .AddOrderRow(Item.OrderRow()
                                                                                .SetAmountExVat(4)
                                                                                .SetVatPercent(25)
                                                                                .SetQuantity(1))
                                                               .AddFee(Item.ShippingFee())
                                                               .AddDiscount(Item.FixedDiscount())
                                                               .AddDiscount(Item.RelativeDiscount());

                    var payment = new FakeHostedPayment(order);
                    payment.CalculateRequestValues();
                });

            Assert.That(exception.Message, Is.EqualTo(expectedMessage));
        }