using System;

using System.Collections.Generic;

using System.Text;

using System.Linq;

using System.Xml.Serialization;

using System.Xml;

using System.Xml.Linq;

using System.IO;

using System.Data;

using System.Runtime.Serialization;

using System.Runtime.Serialization.Formatters.Binary;

using System.IO.Compression;

using System.Reflection;

​

using NUnit.Framework; //NUnit.Framework.AssertionException

​

//https://stackoverflow.com/questions/73127531/how-to-add-a-new-node-to-an-existing-xml-using-c-sharp

​

    public class TestClass

    {

        public static void Test()

        {

            var xmlString = 

                """

                <someOuterElementNotShown>

                <title>Discourse interaction between <italic>The New York Times</italic> and <italic>China Daily</italic></title> <subtitle>The case of Google&#x0027;s departure</subtitle>

                </someOuterElementNotShown>

                """;

            var xml = XElement.Parse(xmlString);

​

            Console.WriteLine(xml);

            var title = xml.Element("title"); // Add some null check here?

            var subtitles = string.Concat(title.ElementsAfterSelf().TakeWhile(e => e.Name == "subtitle").Select(e => e.Value)).Trim();

            var x = subtitles.Length > 0 ? string.Format("{0}: {1}", title.Value.Trim(), subtitles) : xml.Value.Trim();

            Console.WriteLine(x);

            Assert.AreEqual("Discourse interaction between The New York Times and China Daily: The case of Google's departure", x);

        }

    }

​

    public class Program

    {

        public static void Main()

        {

            Console.WriteLine("Environment version: {0} ({1}, {2})", System.Runtime.InteropServices.RuntimeInformation.FrameworkDescription , Environment.Version, Environment.OSVersion);

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

                Console.WriteLine("Failed with unhandled exception: ");

                Console.WriteLine(ex);

                throw;

            }

        }

    }

​