More info in test output

Trying to figure out socket failure discrepancies on Appveyor.

StackExchange.Redis.Tests/Booksleeve/BookSleeveTestBase.cs

-using System;
+using StackExchange.Redis.Tests.Helpers;
+using System;
 using System.Diagnostics;
 using System.Threading.Tasks;
 using Xunit;
@@ -9,7 +10,11 @@ namespace StackExchange.Redis.Tests.Booksleeve
     public class BookSleeveTestBase
     {
         public ITestOutputHelper Output { get; }
-        public BookSleeveTestBase(ITestOutputHelper output) => Output = output;
+        public BookSleeveTestBase(ITestOutputHelper output)
+        {
+            Output = output;
+            Output.WriteFrameworkVersion();
+        }
 
         static BookSleeveTestBase()
         {

StackExchange.Redis.Tests/Booksleeve/Config.cs

@@ -54,7 +54,7 @@ public void CanNotOpenNonsenseConnection_IP()
         [Fact]
         public async Task CanNotOpenNonsenseConnection_DNS()
         {
-            await Assert.ThrowsAsync<RedisConnectionException>(async () =>
+            var ex = await Assert.ThrowsAsync<RedisConnectionException>(async () =>
             {
                 var log = new StringWriter();
                 try
@@ -68,6 +68,7 @@ public async Task CanNotOpenNonsenseConnection_DNS()
                     Output.WriteLine(log.ToString());
                 }
             }).ForAwait();
+            Output.WriteLine(ex.ToString());
         }
 
         [Fact]

StackExchange.Redis.Tests/Helpers/Extensions.cs

+using Xunit.Abstractions;
+
+namespace StackExchange.Redis.Tests.Helpers
+{
+    public static class Extensions
+    {
+        public static void WriteFrameworkVersion(this ITestOutputHelper output)
+        {
+#if NET462
+            output.WriteLine("Compiled under .NET 4.6.2");
+#elif NETCOREAPP1_0
+            output.WriteLine("Compiled under .NETCoreApp1.0");
+#elif NETCOREAPP2_0
+            output.WriteLine("Compiled under .NETCoreApp2.0");
+#else
+            output.WriteLine("Compiled under <unknown framework>");
+#endif
+        }
+    }
+}

StackExchange.Redis.Tests/TestBase.cs

@@ -23,6 +23,7 @@ public abstract class TestBase : IDisposable
         protected TestBase(ITestOutputHelper output)
         {
             Output = output;
+            Output.WriteFrameworkVersion();
             Writer = new TextWriterOutputHelper(output);
             socketManager = new SocketManager(GetType().Name);
             ClearAmbientFailures();