private void MakePayment_button_Click(object sender, RoutedEventArgs e)
 {
     if (Surname_ManageBooking_combo.Items.Count == 0)
     {
         MessageBox.Show("Please search for a customer to make payment");
     }
     else
     {
         int chosenCustomerID = int.Parse(this.Surname_ManageBooking_combo.SelectedValue.ToString());
         if (AvailableBookings_DataGrid.SelectedIndex == 1)
         {
             MessageBox.Show("Empty row - Please select a valid booking");
         }
         else
         {
             if (CustomerClass.getAllBookkingsMadeByCustomer(chosenCustomerID).Tables[0].Rows.Count == 0)
             {
                 MessageBox.Show("No Booking available for payment");
             }
             else
             {
                 DataRowView chosenRow = (DataRowView)AvailableBookings_DataGrid.SelectedItem;
                 int         chosenId  = int.Parse(chosenRow["Booking_Id"].ToString());
                 BookingsClass.payBooking(chosenId);
                 MessageBox.Show("Payment complete");
             }
         }
     }
 }
        public void testPayBooking()
        {
            BookingsClass.payBooking(1);
            dataSet = BookingsClass.getBookingDetailsById(1);

            int actualPaid = int.Parse(dataSet.Tables[0].Rows[0]["Paid"].ToString());

            int expectedPaid = 1;

            Assert.AreEqual(expectedPaid, actualPaid);
        }