using System;

using System.Collections.Generic;

using System;

using System.Linq;

using System.Xml;                   

using System.Xml.Linq;

using System.Collections; 

using System.Collections.Generic;

using System.Data;

using System.Data.DataSetExtensions;

using System.Data.Linq;

using System.Text;

using System.Text.RegularExpressions;

using System.Xml.Serialization; 

using System.IO;

using System.Globalization;

using System.Diagnostics;

using System.Collections.Concurrent;

public class Program

{

    public static void Main()

    {

        string input = @"<testsuite name=""Tests"" rxversion=""5.4.5.19886"" id=""d1203701-d61c-4ae6-932d-faa44beb925a"" reportfilename=""%S_%Y%M%D_%T.rxlog"" reporttemplatefolder="""" reportxslfilename="""" placescreenshotsinfolder=""True"" ReportTime=""RelativeToTestSuiteStartTime"" reportwriteinterval=""30000ms"" reportcompress=""False"" enabletracingscreenshots=""True"" TracingScreenshotMode=""Foreground"" TracingScreenshotQuality=""40"" reportlevel=""Info;20"" warnunboundvariables=""False"">

<testconfigurations default=""TestRun"">

    <testconfiguration name=""TestRun"" />

</testconfigurations>

</testsuite>";

        XDocument doc = XDocument.Parse(input);

        foreach(var element in doc.Descendants("testconfiguration"))

        {

            element.Add(new XElement("testcase", new XAttribute("id","450c9a87-75dc-4538-bc2c-6df6eb359d2a") ));

        }

        doc.ToString().Dump();

    }

}