Acme.Biz.Vendor.PlaceOrder C# (CSharp) Method

        public OperationResult PlaceOrder(Product product, int quantity,
                                            DateTimeOffset? deliverBy = null,
                                            string instructions = "standard delivery")
        {
            if (product == null)
                throw new ArgumentNullException("product");
            if (quantity <= 0)
                throw new ArgumentOutOfRangeException("quantity");
            if (deliverBy <= DateTimeOffset.Now)
                throw new ArgumentOutOfRangeException("deliverBy");

            var success = false;

            var orderTextBuilder = new StringBuilder("Order from Acme, Inc" +
                            System.Environment.NewLine +
                            "Product: " + product.ProductName +
                            System.Environment.NewLine +
                            "Quantity: " + quantity);
            if (deliverBy.HasValue)
            {
                orderTextBuilder.Append( System.Environment.NewLine +
                            "Deliver By: " + deliverBy.Value.ToString("d"));
            }
            if (!String.IsNullOrWhiteSpace(instructions))
            {
                orderTextBuilder.Append( System.Environment.NewLine +
                            "Instructions: " + instructions);
            }
            var orderText = orderTextBuilder.ToString();

            var emailService = new EmailService();
            var confirmation = emailService.SendMessage("New Order", orderText,
                                                                     this.Email);
            if (confirmation.StartsWith("Message sent:"))
            {
                success = true;
            }
            var operationResult = new OperationResult(success, orderText);
            return operationResult;
        }

        public void PlaceOrderTest_NullProduct_Exception()
        {
            // Arrange
            var vender = new Vendor();

            // Act
            var actual = vender.PlaceOrder(null, 12);

            // Assert
        }