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/57888050/accessing-a-sub-attribute-in-a-xml-file-using-xelement

​

    public class TestClass

    {

        public static void Test()

        {

            XElement ticketRootXElement = XElement.Parse(GetXml());

​

            var featureName = "psk:PageMediaSize";

            var newOptionValue = "psk:ISOA3"; // Your modified value here

​

            XNamespace xns_psf = @"http://schemas.microsoft.com/windows/2003/08/printing/printschemaframework";

            var query = from f in ticketRootXElement.DescendantsAndSelf(xns_psf + "Feature")

                        where (string)f.Attribute("name") == featureName

                        select f;

            foreach (var f in query)

            {

                // TODO: handle the situation were a child <psf:Option> element is missing.

                f.Element(xns_psf + "Option").SetAttributeValue("name", newOptionValue);

            }

            Console.WriteLine(ticketRootXElement);

            Assert.IsTrue(ticketRootXElement.ToString().Contains(newOptionValue));

        }

        static string GetXml()

        {

            var xml = @"<?xml version=""1.0""?>

<psf:Feature xmlns:psf=""http://schemas.microsoft.com/windows/2003/08/printing/printschemaframework"" name=""psk:PageMediaSize"">

    <psf:Option name=""psk:ISOA4"">

        <psf:ScoredProperty name=""psk:MediaSizeWidth"">

            <psf:Value xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xsi:type=""xsd:integer"">210000</psf:Value>

        </psf:ScoredProperty>

        <psf:ScoredProperty name=""psk:MediaSizeHeight"">

            <psf:Value xmlns:xsi=""http://www.w3.org/2001/XMLSchema-instance"" xsi:type=""xsd:integer"">297000</psf:Value>

        </psf:ScoredProperty>

    </psf:Option>

</psf:Feature>

";

            return xml;

        }

    }

​

    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;

        }

    }

​