Event handler for Unity Visual Studio 2015 to allow StyleCopAnalyzers to work properly. Credit: jwvanderbeck @ https://forum.unity3d.com/threads/unity-strips-out-nuget-properties-on-csproj-files.473016/. See also https://github.com/jizc/WitchWing/blob/master/WitchWing/Assets/Scripts/Editor/ProjectFileHook.cs

gistfile1.cs

#if UNITY_EDITOR_WIN
using System.IO;
using System.Text;
using System.Xml.Linq;
using SyntaxTree.VisualStudio.Unity.Bridge;
using UnityEditor;
 
/// <summary>
/// Provide a hook into Unity's Project File Generation so that StyleCop gets re-added each time
/// </summary>
[InitializeOnLoad]
public class ProjectFileHook
{
    static ProjectFileHook()
    {
        ProjectFilesGenerator.ProjectFileGeneration += (string name, string content) =>
        {
            // parse the document and make some changes
            var document = XDocument.Parse(content);
            XNamespace xmlns = "http://schemas.microsoft.com/developer/msbuild/2003";
            XElement itemGroup = new XElement(xmlns + "ItemGroup");
            itemGroup.Add(new XElement(xmlns + "Analyzer", new XAttribute("Include", "packages\\StyleCop.Analyzers.1.0.2\\analyzers\\dotnet\\cs\\StyleCop.Analyzers.CodeFixes.dll")));
            itemGroup.Add(new XElement(xmlns + "Analyzer", new XAttribute("Include", "packages\\StyleCop.Analyzers.1.0.2\\analyzers\\dotnet\\cs\\StyleCop.Analyzers.dll")));
            document.Root.Add(itemGroup);
            document.Root.Add(new XElement(xmlns + "ItemGroup", new XElement(xmlns + "AdditionalFiles", new XAttribute("Include", "stylecop.json"))));
 
            // save the changes using the Utf8StringWriter
            var str = new Utf8StringWriter();
            document.Save(str);
 
            return str.ToString();
        };
    }
 
    // necessary for XLinq to save the xml project file in utf8
    private class Utf8StringWriter : StringWriter
    {
        public override Encoding Encoding
        {
            get { return Encoding.UTF8; }
        }
    }
}
#endif