Edit csproj file via C#

editcsproj.cs

private static void AddFilesToUnitTestProject(FileInfo[] files, string measureBaseDirPath, string measureDataDirSuffix)
    {
        var unitTestProjectPath = measureBaseDirPath + _unitTestProjectFile;
        var unitTestProjectFile = XDocument.Load(unitTestProjectPath);
        var itemGroup = unitTestProjectFile.Nodes()
                          .OfType<XElement>()
                          .DescendantNodes()
                          .OfType<XElement>().First(xy => xy.Name.LocalName == "ItemGroup");

        foreach (var fileInfo in files)
        {
            var xelem = AddProjectContent(measureDataDirSuffix + fileInfo.Name, unitTestProjectFile);
            itemGroup.Add(xelem);
        }
        unitTestProjectFile.Save(unitTestProjectPath);
    }

    private static void AddFileToUnitTestProject(string pathToAdd, string measureBaseDirPath, string measureDataDir)
    {
        var unitTestProjectPath = measureBaseDirPath + _unitTestProjectFile;
        var unitTestProjectFile = XDocument.Load(unitTestProjectPath);
        var itemGroup =
        unitTestProjectFile.Nodes()
                           .OfType<XElement>()
                           .DescendantNodes()
                           .OfType<XElement>().First(xy => xy.Name.LocalName == "ItemGroup");
        var xelem = AddProjectContent(pathToAdd, unitTestProjectFile);
        itemGroup.Add(xelem);
        unitTestProjectFile.Save(unitTestProjectPath);
    }