Prevent duplication of ErrorManager and TraceSettings handlers

libs/UIX.Test/Fixtures/MarkupSystemFixture.cs

@@ -1,17 +1,76 @@
 using Microsoft.Iris.Asm;
+using Microsoft.Iris.Debug;
 using Microsoft.Iris.Markup;
+using Microsoft.Iris.Session;
+using System.Collections;
+using Xunit.Abstractions;
 
 namespace UIX.Test.Fixtures;
 
 public class MarkupSystemFixture : IDisposable
 {
+    private ITestOutputHelper? _output;
+    private static bool _handlersInitialized = false;
+
     public MarkupSystemFixture()
     {
+        string zuneDirectory = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.ProgramFiles), "Zune");
+        if (Directory.Exists(zuneDirectory))
+        {
+            // Zune is installed, attempt to copy the required UIX dependencies
+            var workingDirectory = Environment.CurrentDirectory;
+            IEnumerable<string> irisDependencies = ["UIXRender.dll", "UIXControls.dll"];
+
+            foreach (string irisDependency in irisDependencies)
+            {
+                var dstFilePath = Path.Combine(workingDirectory, irisDependency);
+                if (Path.Exists(dstFilePath))
+                    continue;
+
+                var srcFilePath = Path.Combine(zuneDirectory, irisDependency);
+                if (!Path.Exists(srcFilePath))
+                    continue;
+
+                File.Copy(srcFilePath, dstFilePath);
+            }
+        }
+
         MarkupSystem.Startup(true);
         Assembler.RegisterLoader();
     }
 
-    public void Dispose() => MarkupSystem.Shutdown();
+    public void SetupDebug(ITestOutputHelper output)
+    {
+        _output = output;
+
+        if (!_handlersInitialized)
+        {
+            _handlersInitialized = true;
+            ErrorManager.OnErrors += PrintMarkupErrors;
+            TraceSettings.Current.OnWriteLine += PrintLine;
+        }
+    }
+
+    public void Dispose()
+    {
+        MarkupSystem.Shutdown();
+        ErrorManager.OnErrors -= PrintMarkupErrors;
+        TraceSettings.Current.OnWriteLine -= PrintLine;
+    }
+
+    private void PrintMarkupErrors(IList errors)
+    {
+        if (_output is null)
+            return;
+
+        foreach (ErrorRecord error in errors)
+        {
+            var errorTypeText = error.Warning ? "Warning" : "Error";
+            _output.WriteLine($"{errorTypeText} at (L{error.Line}, C{error.Column}): {error.Message}");
+        }
+    }
+
+    private void PrintLine(string line) => _output?.WriteLine(line);
 }
 
 [CollectionDefinition("MarkupSystem")]