Empty message body fix (#1889)

* if body empty on send, return an empty body on receive

* change to treat an empty message as null

* change to use string.Empty instead of null

* fix empty message magic string

* test for "empty message" body translation

* Cleanup and use different asserts

* Reverting to use the "empty message" magic string

---------

Co-authored-by: danielmarbach <daniel.marbach@openplace.net>

src/NServiceBus.Transport.SQS.Tests/InputQueuePumpTests.cs

@@ -116,7 +116,7 @@ public async Task Expired_messages_are_deleted_without_processing()
                     {Headers.MessageId, messageId},
                     {TransportHeaders.TimeToBeReceived, ttbr.ToString()}
                 },
-                Body = "empty message"
+                Body = TransportMessage.EmptyMessage
             });
 
             var message = new Message
@@ -161,7 +161,7 @@ public async Task Processed_messages_are_deleted()
                 {
                     {Headers.MessageId, messageId}
                 },
-                Body = "empty message"
+                Body = TransportMessage.EmptyMessage
             });
 
             var message = new Message

src/NServiceBus.Transport.SQS.Tests/TransportMessageTests.cs

@@ -2,11 +2,13 @@
 {
     using System;
     using System.Collections.Generic;
+    using System.Text;
     using System.Text.Json;
+    using System.Threading.Tasks;
+    using NServiceBus.Transport.SQS.Extensions;
     using NServiceBus;
     using NUnit.Framework;
     using Performance.TimeToBeReceived;
-    using SQS;
     using Transport;
 
     [TestFixture]
@@ -131,7 +133,7 @@ public void Can_be_built_from_serialized_v1_message()
                 {
                     {Headers.MessageId, Guid.Empty.ToString()}
                 },
-                Body = "empty message",
+                Body = TransportMessage.EmptyMessage,
                 S3BodyKey = (string)null,
                 TimeToBeReceived = ExpectedTtbr.ToString(),
                 ReplyToAddress = new TransportMessage.Address
@@ -158,7 +160,7 @@ public void Can_be_built_from_serialized_message()
                 {
                     {Headers.MessageId, Guid.Empty.ToString()}
                 },
-                Body = "empty message",
+                Body = TransportMessage.EmptyMessage,
                 S3BodyKey = (string)null
             });
 
@@ -170,6 +172,50 @@ public void Can_be_built_from_serialized_message()
             Assert.IsNull(transportMessage.ReplyToAddress, "ReplyToAddress was not null.");
         }
 
+        [Test]
+        public async Task Empty_body_is_received_ok()
+        {
+            var messageId = Guid.NewGuid().ToString();
+            var body = Array.Empty<byte>();
+            var outgoingMessage = new OutgoingMessage(messageId, new Dictionary<string, string>(), body);
+
+            var transportMessage = new TransportMessage(outgoingMessage, new DispatchProperties());
+
+            var receivedBodyArray = await transportMessage.RetrieveBody(messageId, null);
+            var receivedBody = Encoding.Unicode.GetString(receivedBodyArray);
+
+            CollectionAssert.AreEqual(receivedBodyArray, body);
+            Assert.That(receivedBody, Is.Null.Or.Empty);
+        }
+
+        [Test]
+        public async Task Null_body_is_received_ok()
+        {
+            var messageId = Guid.NewGuid().ToString();
+            var outgoingMessage = new OutgoingMessage(messageId, new Dictionary<string, string>(), null);
+
+            var transportMessage = new TransportMessage(outgoingMessage, new DispatchProperties());
+
+            var receivedBodyArray = await transportMessage.RetrieveBody(messageId, null);
+            var receivedBody = Encoding.Unicode.GetString(receivedBodyArray);
+
+            Assert.That(receivedBody, Is.Null.Or.Empty);
+        }
+
+        [Test]
+        public async Task Empty_message_string_body_is_received_as_empty()
+        {
+            var transportMessage = new TransportMessage
+            {
+                Body = "empty message",
+            };
+
+            var receivedBodyArray = await transportMessage.RetrieveBody(Guid.NewGuid().ToString(), null);
+            var receivedBody = Encoding.Unicode.GetString(receivedBodyArray);
+
+            Assert.That(receivedBody, Is.Null.Or.Empty);
+        }
+
         const string ExpectedReplyToAddress = "TestReplyToAddress";
         static readonly TimeSpan ExpectedTtbr = TimeSpan.MaxValue.Subtract(TimeSpan.FromHours(1));
     }

src/NServiceBus.Transport.SQS/Extensions/MessageExtensions.cs

@@ -15,7 +15,14 @@ static class MessageExtensions
         {
             if (string.IsNullOrEmpty(transportMessage.S3BodyKey))
             {
-                return Convert.FromBase64String(transportMessage.Body);
+                if (transportMessage.Body == TransportMessage.EmptyMessage)
+                {
+                    return Array.Empty<byte>();
+                }
+                else
+                {
+                    return Convert.FromBase64String(transportMessage.Body);
+                }
             }
 
             if (s3Settings == null)
@@ -51,4 +58,4 @@ public static DateTimeOffset GetAdjustedDateTimeFromServerSetAttributes(this Mes
 
         static readonly DateTimeOffset UnixEpoch = new DateTimeOffset(1970, 1, 1, 0, 0, 0, TimeSpan.Zero);
     }
-}
+}

src/NServiceBus.Transport.SQS/TransportMessage.cs

@@ -6,6 +6,9 @@
 
     class TransportMessage
     {
+        //MessageBody of Amazon.SQS SendRequest must have a minimum length of 1: https://docs.aws.amazon.com/AWSSimpleQueueService/latest/APIReference/API_SendMessage.html
+        public const string EmptyMessage = "empty message";
+
         // Empty constructor required for deserialization.
         public TransportMessage()
         {
@@ -28,9 +31,9 @@ public TransportMessage(OutgoingMessage outgoingMessage, DispatchProperties prop
             }
 
 #if NETFRAMEWORK
-            Body = outgoingMessage.Body.Length != 0 ? Convert.ToBase64String(outgoingMessage.Body.ToArray()) : "empty message";
+            Body = outgoingMessage.Body.Length != 0 ? Convert.ToBase64String(outgoingMessage.Body.ToArray()) : EmptyMessage;
 #else
-            Body = outgoingMessage.Body.Length != 0 ? Convert.ToBase64String(outgoingMessage.Body.Span) : "empty message";
+            Body = outgoingMessage.Body.Length != 0 ? Convert.ToBase64String(outgoingMessage.Body.Span) : EmptyMessage;
 #endif
         }