Enable MessagingEventSource logging to comply with the rest of SendAsync methods

Author: SeanFeldman

src/Microsoft.Azure.ServiceBus/Core/Batch.cs

@@ -63,10 +63,16 @@ public bool TryAdd(Message message)
 
         }
 
+        /// <summary>
+        /// Number of messages in batch.
+        /// </summary>
+        public int Length => datas.Count;
+
         private long Size => result.SerializedMessageSize;
 
+
         /// <summary>
-        /// Convert batch to AMQP message
+        /// Convert batch to AMQP message.
         /// </summary>
         /// <returns></returns>
         public AmqpMessage ToAmqpMessage()

src/Microsoft.Azure.ServiceBus/Core/MessageSender.cs

@@ -277,7 +277,7 @@ public async Task SendAsync(Batch batch)
         {
             this.ThrowIfClosed();
 
-//            MessagingEventSource.Log.MessageSendStart(this.ClientId, count);
+            MessagingEventSource.Log.MessageSendStart(this.ClientId, batch.Length);
 
 //            var isDiagnosticSourceEnabled = ServiceBusDiagnosticSource.IsEnabled();
 //            var activity = isDiagnosticSourceEnabled ? this.diagnosticSource.SendStart(messageList) : null;

test/Microsoft.Azure.ServiceBus.UnitTests/API/ApiApprovals.ApproveAzureServiceBus.approved.txt

@@ -483,6 +483,7 @@ namespace Microsoft.Azure.ServiceBus.Core
     public class Batch : System.IDisposable
     {
         public Batch(long maximumBatchSize) { }
+        public int Length { get; }
         public void Dispose() { }
         public Microsoft.Azure.Amqp.AmqpMessage ToAmqpMessage() { }
         public bool TryAdd(Microsoft.Azure.ServiceBus.Message message) { }

test/Microsoft.Azure.ServiceBus.UnitTests/Primitives/BatchTests.cs

@@ -41,5 +41,21 @@ public void Should_throw_when_trying_to_add_an_already_received_message_to_batch
                 Assert.Throws<ArgumentException>(() => batch.TryAdd(message));
             }
         }
+
+        [Theory]
+        [InlineData(1)]
+        [InlineData(3)]
+        public void Should_report_how_many_messages_are_in_batch(int numberOfMessages)
+        {
+            using (var batch = new Batch(100))
+            {
+                for (var i = 0; i < numberOfMessages; i++)
+                {
+                    batch.TryAdd(new Message());
+                }
+
+                Assert.Equal(numberOfMessages, batch.Length);
+            }
+        }
     }
 }