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/59791655/why-is-does-this-xmlnodelist-count-become-0

​

    public class TestClass

    {

        public static void Test()

        {

            TestSucceeds();

            TestFails();

        }

        static void TestSucceeds()

        {

            XmlDocument doc = new XmlDocument();

            doc.LoadXml(GetXml());

​

            //doc.Load(@"C:\Users\Username\Desktop\Diagram.xml");

​

            XmlNodeList nodelist = doc.SelectNodes("*/*"); // Select all children of the root node

            RemoveChildren(doc.DocumentElement);

            Assert.IsTrue(nodelist.Count == 0); // Passes

        }

​

        static void TestFails()

        {

            XmlDocument doc = new XmlDocument();

            doc.LoadXml(GetXml());

​

            //doc.Load(@"C:\Users\Username\Desktop\Diagram.xml");

​

            XmlNodeList nodelist = doc.SelectNodes("*/*"); // Select all children of the root node

            Assert.IsTrue(nodelist.Count > 0);  // Passes

            RemoveChildren(doc.DocumentElement);

            Assert.IsTrue(nodelist.Count == 0); // FAILS!?

        }

        private static XmlNode RemoveChildren(XmlNode n) {

​

            while (n.FirstChild != null)

            {

                n.RemoveChild(n.FirstChild);

            }

​

            return n;

        }

        static string GetXml()

        {

            var xml = @"<mxGraphModel dx=""1086"" dy=""596"" grid=""1"" gridSize=""10"" guides=""1"" tooltips=""1"" connect=""1"" arrows=""1"" fold=""1"" page=""1"" pageScale=""1"" pageWidth=""850"" pageHeight=""1100"" math=""0"" shadow=""0"">

  <root>

    <mxCell id=""0""/>

    <mxCell id=""1"" parent=""0""/>

    <mxCell id=""YJb7HCrh72y2aGPrfETQ-1"" value="""" style=""endArrow=classic;html=1;"" parent=""1"" edge=""1"">

      <mxGeometry width=""50"" height=""50"" relative=""1"" as=""geometry"">

        <mxPoint x=""130"" y=""310"" as=""sourcePoint""/>

        <mxPoint x=""180"" y=""260"" as=""targetPoint""/>

      </mxGeometry>

    </mxCell>

    <mxCell id=""YJb7HCrh72y2aGPrfETQ-2"" value="""" style=""endArrow=classic;html=1;"" parent=""1"" edge=""1"">

      <mxGeometry width=""50"" height=""50"" relative=""1"" as=""geometry"">

        <mxPoint x=""290"" y=""270"" as=""sourcePoint""/>

        <mxPoint x=""340"" y=""220"" as=""targetPoint""/>

      </mxGeometry>

    </mxCell>

  </root>

</mxGraphModel>";

            return xml;

        }

    }

​

    public static class XmlSerializationHelper

    {

        public static T LoadFromXml<T>(this string xmlString, XmlSerializer serial = null)

        {

            serial = serial ?? new XmlSerializer(typeof(T));

            using (var reader = new StringReader(xmlString))

            {

                return (T)serial.Deserialize(reader);

            }

        }

​

        public static string GetXml<T>(this T obj, XmlSerializer serializer = null, bool omitStandardNamespaces = false)

        {

            XmlSerializerNamespaces ns = null;

            if (omitStandardNamespaces)

            {

                ns = new XmlSerializerNamespaces();

                ns.Add("", ""); // Disable the xmlns:xsi and xmlns:xsd lines.

            }           

            using (var textWriter = new StringWriter())

            {

                var settings = new XmlWriterSettings() { Indent = true }; // For cosmetic purposes.

                using (var xmlWriter = XmlWriter.Create(textWriter, settings))

                    (serializer ?? new XmlSerializer(obj.GetType())).Serialize(xmlWriter, obj, ns);

                return textWriter.ToString();

            }

        }

        public static string GetOuterXml(this XmlNode node, bool indent = true)

        {

            if (node == null)

                return null;

            using (var textWriter = new StringWriter())

            {

                var settings = new XmlWriterSettings

                {

                    Indent = indent,

                    OmitXmlDeclaration = true,

                };

                using (var xmlWriter = XmlWriter.Create(textWriter, settings))

                {

                    node.WriteTo(xmlWriter);

                }

                return textWriter.ToString();

            }

        }

    }

​

    public class Program

    {

        public static void Main()

        {

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

            Console.WriteLine();

​

            try

            {

                TestClass.Test();

            }

            catch (Exception ex)

            {

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

                Console.WriteLine(ex);

                throw;

            }

        }

        public static string GetNetCoreVersion()

        {

            //https://techblog.dorogin.com/how-to-detect-net-core-version-in-runtime-ecd65ad695be

            //

            var assembly = typeof(System.Runtime.GCSettings).GetTypeInfo().Assembly;

            var assemblyPath = assembly.CodeBase.Split(new[] { '/', '\\' }, StringSplitOptions.RemoveEmptyEntries);

            int netCoreAppIndex = Array.IndexOf(assemblyPath, "Microsoft.NETCore.App");

            if (netCoreAppIndex > 0 && netCoreAppIndex < assemblyPath.Length - 2)

                return assemblyPath[netCoreAppIndex + 1];

            return null;

        }

    }

​