Handles null values in MessageType and ContentType metadata fields when publishing external integration events.

Fixes #423

Author: SzymonPobiega

…lIntegrationsFailedMessagesIndexTests.cs …egrations/MessageFailedConverterTests.cssrc/ServiceControl.UnitTests/ExternalIntegrations/ExternalIntegrationsFailedMessagesIndexTests.cs renamed to src/ServiceControl.UnitTests/ExternalIntegrations/MessageFailedConverterTests.cs src/ServiceControl.UnitTests/ExternalIntegrations/ExternalIntegrationsFailedMessagesIndexTests.cs renamed to src/ServiceControl.UnitTests/ExternalIntegrations/MessageFailedConverterTests.cs

@@ -11,7 +11,7 @@
     using FailureDetails = ServiceControl.Contracts.Operations.FailureDetails;
 
     [TestFixture]
-    public class ExternalIntegrationsFailedMessagesIndexTests
+    public class MessageFailedConverterTests
     {
         [Test]
         public void Archive_status_maps_to_archive()
@@ -59,6 +59,30 @@ public void If_not_present_in_metadata_body_is_ignored()
             Assert.IsNull(result.MessageDetails.Body);
         }
 
+        [Test]
+        public void If_message_type_is_missing_it_is_ignored()
+        {
+            var failedMessage = new FailedMessageBuilder(FailedMessageStatus.Unresolved)
+                .SetMessageType(null)
+                .AddProcessingAttempt(pa => { })
+                .Build();
+
+            var result = failedMessage.ToEvent();
+            Assert.IsNull(result.MessageType);
+        } 
+        
+        [Test]
+        public void If_content_type_is_missing_it_is_ignored()
+        {
+            var failedMessage = new FailedMessageBuilder(FailedMessageStatus.Unresolved)
+                .SetContentType(null)
+                .AddProcessingAttempt(pa => { })
+                .Build();
+
+            var result = failedMessage.ToEvent();
+            Assert.IsNull(result.MessageDetails.ContentType);
+        }
+
         [Test]
         public void Body_is_mapped_from_metadata_of_last_processing_attempt()
         {
@@ -73,13 +97,27 @@ public void Body_is_mapped_from_metadata_of_last_processing_attempt()
         private class FailedMessageBuilder
         {
             private readonly FailedMessageStatus messageStatus;
+            string messageType = "SomeMessage";
+            string contentType = "application/json";
             private List<Action<FailedMessage.ProcessingAttempt>> processingAttempts = new List<Action<FailedMessage.ProcessingAttempt>>();
 
             public FailedMessageBuilder(FailedMessageStatus messageStatus)
             {
                 this.messageStatus = messageStatus;
             }
 
+            public FailedMessageBuilder SetMessageType(string messageType)
+            {
+                this.messageType = messageType;
+                return this;
+            }
+
+            public FailedMessageBuilder SetContentType(string contentType)
+            {
+                this.contentType = contentType;
+                return this;
+            }
+
             public FailedMessageBuilder AddProcessingAttempt(Action<FailedMessage.ProcessingAttempt> callback)
             {
                 processingAttempts.Add(callback);
@@ -92,19 +130,26 @@ public FailedMessage Build()
                 {
                     ProcessingAttempts = processingAttempts.Select(x =>
                     {
+                        var messageMetadata = new Dictionary<string, object>
+                        {
+                            {"SendingEndpoint",new Contracts.Operations.EndpointDetails()},
+                            {"ReceivingEndpoint",new Contracts.Operations.EndpointDetails()},
+                        };
+                        if (messageType != null)
+                        {
+                            messageMetadata["MessageType"] = messageType;
+                        }
+                        if (contentType != null)
+                        {
+                            messageMetadata["ContentType"] = contentType;
+                        }
                         var attempt = new FailedMessage.ProcessingAttempt
                         {
                             FailureDetails = new FailureDetails
                             {
                                 Exception = new ExceptionDetails()
                             },
-                            MessageMetadata = new Dictionary<string, object>
-                            {
-                                {"SendingEndpoint",new Contracts.Operations.EndpointDetails()},
-                                {"ReceivingEndpoint",new Contracts.Operations.EndpointDetails()},
-                                {"MessageType","SomeMessage"},
-                                {"ContentType","application/json"},
-                            },
+                            MessageMetadata = messageMetadata,
                         };
                         x(attempt);
                         return attempt;

src/ServiceControl.UnitTests/ServiceControl.UnitTests.csproj

@@ -89,7 +89,7 @@
     <Reference Include="System.Xml.Linq" />
   </ItemGroup>
   <ItemGroup>
-    <Compile Include="ExternalIntegrations\ExternalIntegrationsFailedMessagesIndexTests.cs" />
+    <Compile Include="ExternalIntegrations\MessageFailedConverterTests.cs" />
     <Compile Include="CompositeViews\MessagesViewTests.cs" />
     <Compile Include="Expiration\CustomExpirationBundleTests.cs" />
     <Compile Include="Heartbeats\HeartbeatStatusProviderTests.cs" />

src/ServiceControl/ExternalIntegrations/MessageFailedConverter.cs

@@ -1,5 +1,6 @@
 namespace ServiceControl.ExternalIntegrations
 {
+    using System.Collections.Generic;
     using System.Linq;
     using ServiceControl.Contracts.Operations;
     using ServiceControl.MessageFailures;
@@ -10,13 +11,12 @@ public static Contracts.MessageFailed ToEvent(this FailedMessage message)
         {
             var last = message.ProcessingAttempts.Last();
             var sendingEndpoint = (EndpointDetails)last.MessageMetadata["SendingEndpoint"];
-            object tmp;
-            last.MessageMetadata.TryGetValue("ReceivingEndpoint", out tmp);
-            var receivingEndpoint = (EndpointDetails) tmp;
+            var receivingEndpoint = GetNullableMetadataValue<EndpointDetails>(last.MessageMetadata, "ReceivingEndpoint");
+
             return new Contracts.MessageFailed
             {
                 FailedMessageId = message.UniqueMessageId,
-                MessageType = (string)last.MessageMetadata["MessageType"],
+                MessageType = GetNullableMetadataValue<string>(last.MessageMetadata,"MessageType"),
                 NumberOfProcessingAttempts = message.ProcessingAttempts.Count,
                 Status = message.Status == FailedMessageStatus.Archived
                     ? Contracts.MessageFailed.MessageStatus.ArchivedFailure
@@ -38,7 +38,7 @@ public static Contracts.MessageFailed ToEvent(this FailedMessage message)
                 MessageDetails = new Contracts.MessageFailed.Message
                 {
                     Headers = last.Headers,
-                    ContentType = (string)last.MessageMetadata["ContentType"],
+                    ContentType = GetNullableMetadataValue<string>(last.MessageMetadata, "ContentType"),
                     Body = GetBody(last),
                     MessageId = last.MessageId,
                 },
@@ -57,6 +57,14 @@ public static Contracts.MessageFailed ToEvent(this FailedMessage message)
             };
         }
 
+        static T GetNullableMetadataValue<T>(IReadOnlyDictionary<string, object> metadata, string key)
+            where T : class 
+        {
+            object value;
+            metadata.TryGetValue(key, out value);
+            return (T)value;
+        }
+
         static string GetBody(FailedMessage.ProcessingAttempt last)
         {
             object body;