Fix Debug.Assert behavior to match xunit <2.0

SteamKit2/Tests/ClientMsgFacts.cs

@@ -1,5 +1,6 @@
 using System;
 using System.Collections.Generic;
+using System.Diagnostics;
 using System.Linq;
 using System.Text;
 using SteamKit2;
@@ -39,6 +40,16 @@ public class ClientMsgFacts
             0x00,
         };
 
+        public ClientMsgFacts()
+        {
+            // Debug.Assert's default behavior is to display a dialog if the default trace listener is still installed
+            // xunit prior to 2.0 would disable the default trace listener and prevent the assert dialog
+            // since we're now on 2.0, we need to restore this behavior ourselves
+
+            Debug.Listeners.Clear();
+            Debug.Listeners.Add( new TraceAssertListener() );
+        }
+
         [Fact]
         public void PayloadReaderReadsNullTermString()
         {

SteamKit2/Tests/Helpers/TraceAssertListener.cs

@@ -0,0 +1,38 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace Tests
+{
+    class TraceAssertListener : TraceListener
+    {
+        public override void Fail( string message, string detailMessage )
+        {
+            throw new TraceAssertException( message, detailMessage );
+        }
+
+        public override void Write( string message )
+        {
+        }
+
+        public override void WriteLine( string message )
+        {
+        }
+    }
+
+    class TraceAssertException : Exception
+    {
+        public string AssertMessage { get; private set; }
+        public string AssertDetailedMessage { get; private set; }
+
+
+        public TraceAssertException( string message, string detailMessage )
+        {
+            AssertMessage = message;
+            AssertDetailedMessage = detailMessage;
+        }
+    }
+}

SteamKit2/Tests/Tests.csproj

@@ -70,7 +70,8 @@
     <Compile Include="ClientMsgFacts.cs" />
     <Compile Include="CMClientFacts.cs" />
     <Compile Include="DebugLogFacts.cs" />
-    <Compile Include="HandlerTestBase.cs" />
+    <Compile Include="Helpers\HandlerTestBase.cs" />
+    <Compile Include="Helpers\TraceAssertListener.cs" />
     <Compile Include="KeyValueFacts.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
     <Compile Include="SmartCMServerListFacts.cs" />
@@ -93,6 +94,7 @@
   <ItemGroup>
     <Service Include="{82A7F48D-3B50-4B1E-B82E-3ADA8210C358}" />
   </ItemGroup>
+  <ItemGroup />
   <Import Project="$(MSBuildToolsPath)\Microsoft.CSharp.targets" />
   <Target Name="EnsureNuGetPackageBuildImports" BeforeTargets="PrepareForBuild">
     <PropertyGroup>