Adapt IsolatedTestHost to xunit.v3

Author: AArnott

Directory.Packages.props

@@ -36,7 +36,7 @@
     <PackageVersion Include="System.Runtime.CompilerServices.Unsafe" Version="6.1.0" />
     <PackageVersion Include="System.Threading.Tasks.Extensions" Version="4.6.0" />
     <PackageVersion Include="System.ValueTuple" Version="4.6.1" />
-    <PackageVersion Include="xunit.abstractions" Version="2.0.3" />
+    <PackageVersion Include="xunit.v3.core.mtp-v2" Version="3.2.1" />
     <PackageVersion Include="Xunit.Combinatorial" Version="2.0.24" />
     <PackageVersion Include="Xunit.StaFact" Version="3.0.13" />
   </ItemGroup>

test/IsolatedTestHost/IsolatedTestHost.csproj

@@ -3,10 +3,11 @@
   <PropertyGroup>
     <OutputType>Exe</OutputType>
     <TargetFrameworks>net472</TargetFrameworks>
+    <IsTestProject>false</IsTestProject>
   </PropertyGroup>
 
   <ItemGroup>
-    <PackageReference Include="xunit.abstractions" />
+    <PackageReference Include="xunit.v3.core.mtp-v2" ExcludeAssets="buildTransitive" />
   </ItemGroup>
 
 </Project>

test/IsolatedTestHost/Program.cs

@@ -52,8 +52,7 @@ private static ExitCode MyMain(string assemblyFile, string testClassName, string
         }
 
         bool fact = testMethod.GetCustomAttributesData().Any(a => a.AttributeType.Name == "FactAttribute");
-        bool skippableFact = testMethod.GetCustomAttributesData().Any(a => a.AttributeType.Name == "SkippableFactAttribute");
-        if (fact || skippableFact)
+        if (fact)
         {
             return ExecuteTest(testClass, testMethod);
         }

test/IsolatedTestHost/TestOutputHelper.cs

@@ -1,20 +1,23 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. See LICENSE file in the project root for full license information.
 
-using System;
-using Xunit.Abstractions;
+using System.Globalization;
+using System.Text;
+using Xunit;
 
 namespace IsolatedTestHost;
 
 internal class TestOutputHelper : ITestOutputHelper
 {
-    public void WriteLine(string message)
-    {
-        Console.WriteLine(message);
-    }
-
-    public void WriteLine(string format, params object[] args)
-    {
-        Console.WriteLine(format, args);
-    }
+    private readonly StringBuilder builder = new();
+
+    public string Output => this.builder.ToString();
+
+    public void Write(string message) => this.builder.Append(message);
+
+    public void Write(string format, params object[] args) => this.builder.AppendFormat(format, args);
+
+    public void WriteLine(string message) => this.builder.AppendLine(message);
+
+    public void WriteLine(string format, params object[] args) => this.builder.AppendLine(string.Format(CultureInfo.CurrentCulture, format, args));
 }