record failure logs even if none passed in

StackExchange.Redis.Tests/TestBase.cs

@@ -202,6 +202,13 @@ protected IServer GetAnyMaster(ConnectionMultiplexer muxer)
             string channelPrefix = null, Proxy? proxy = null,
             string configuration = null,
             [CallerMemberName] string caller = null)
+        {
+            StringWriter localLog = null;
+            if(log == null)
+            {
+                log = localLog = new StringWriter();
+            }
+            try
             {
                 configuration = configuration ?? GetConfiguration();
                 var config = ConfigurationOptions.Parse(configuration);
@@ -266,6 +273,12 @@ protected IServer GetAnyMaster(ConnectionMultiplexer muxer)
                 muxer.Closing += complete => Writer.WriteLine(complete ? "Closed" : "Closing...");
                 return muxer;
             }
+            catch
+            {
+                if (localLog != null) Output?.WriteLine(localLog.ToString());
+                throw;
+            }
+        }
 
         public static string Me([CallerFilePath] string filePath = null, [CallerMemberName] string caller = null) =>
 #if NET462