[wix-devs] Extending UserVerifier

Ron Martin cpuwzd at comcast.net
Tue Aug 9 19:46:28 PDT 2022

Since I've been working on adding user comments for user accounts 
created by Wix installations, I've come up with a need to  extend the 
UserVerifier class used in the MSI end to end tests so that it can aet 
and verify user comments.

Digging into Active Directory for the first time in my life has been a 
real adventure. I've come up with a few MS examples, but  have yet to be 
able to make any of them work.

Here's a stand-alone test that give the essence of my problem:

Start by creating a .net Framework 4.72 console application. Use the 
code below as the only .cs file. Add a reference to 
System.DirectoryServices.AccountManagement. The .cs file should look like:


using System.DirectoryServices.AccountManagement;

namespace UserPrincipalBug
     internal class Program
         static void Main(string[] args)
             WindowsUser user = WindowsUser.GetUser("<put a valid local 
user name here>");
             user.Comment = "This is my comment!";

     public class WindowsUser : UserPrincipal
         public WindowsUser(PrincipalContext context) : base(context)

         public string Comment
                 ExtensionSet("comment", value);

         public static new WindowsUser FindByIdentity(PrincipalContext 
                                                      string identityValue)
             return (WindowsUser)FindByIdentityWithType(context,

         public static WindowsUser GetUser(string userName)
             using (var context = new PrincipalContext(ContextType.Machine))
                 return FindByIdentity(context, IdentityType.Name, 


The problem boils down to FindByIdentityWithType not being able to 
return an object of type WindowsUser. The class that actually implements 
this method is several levels higher in the inheritance hierarchy, i a 
class named Principal. It manages to return an object of type 
UserPrincipal, which is the parent class of WindowsUser, but cannot be 
cast to WindowsUser. Oddly, the code compiles without error and only 
throws an exception at runtime.

All of the examples I have tried run into the same problem. I don't know 
if the code is emitting IL or what kind of trick it is using, but it 
appears to be broken.

If I have to, I'll back up and access the inner structure in a less 
glamorous way, but I'm hoping that the person who wrote UserVerifier can 
set me straight. I'll be listening during Thursday's meeting to see if 
any help is forthcoming. I have some related questions I'd like to ask, 
as well.


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