Refactor subscribe and unsubscribe to support MQTTv5.

Tests/MQTTnet.Core.Tests/MqttPacketReaderTests.cs

@@ -1,7 +1,7 @@
 using System.IO;
 using System.Threading;
+using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
-using MQTTnet.Exceptions;
 using MQTTnet.Formatter;
 using MQTTnet.Internal;
 
@@ -11,12 +11,13 @@ namespace MQTTnet.Tests
     public class MqttPacketReaderTests
     {
         [TestMethod]
-        [ExpectedException(typeof(MqttCommunicationClosedGracefullyException))]
-        public void MqttPacketReader_EmptyStream()
+        public async Task MqttPacketReader_EmptyStream()
         {
             var fixedHeader = new byte[2];
             var reader = new MqttPacketReader(new TestMqttChannel(new MemoryStream()));
-            reader.ReadFixedHeaderAsync(fixedHeader, CancellationToken.None).GetAwaiter().GetResult();
+            var readResult = await reader.ReadFixedHeaderAsync(fixedHeader, CancellationToken.None);
+
+            Assert.IsTrue(readResult.ConnectionClosed);
         }
     }
 }