Fix NPE when SQS message has no message attributes (#213)

Author: normj

.autover/changes/e302a00d-e74f-4520-915c-696f96410f7b.json

@@ -0,0 +1,11 @@
+{
+  "Projects": [
+    {
+      "Name": "AWS.Messaging.Lambda",
+      "Type": "Patch",
+      "ChangelogMessages": [
+        "Fix null pointer exception when message contains no SQS message attributes"
+      ]
+    }
+  ]
+}

src/AWS.Messaging.Lambda/Properties/AssemblyInfo.cs

@@ -0,0 +1,8 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("AWS.Messaging.UnitTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100db5f59f098d27276c7833875a6263a3cc74ab17ba9a9df0b52aedbe7252745db7274d5271fd79c1f08f668ecfa8eaab5626fa76adc811d3c8fc55859b0d09d3bc0a84eecd0ba891f2b8a2fc55141cdcc37c2053d53491e650a479967c3622762977900eddbf1252ed08a2413f00a28f3a0752a81203f03ccb7f684db373518b4")]
+[assembly: InternalsVisibleTo("AWS.Messaging.IntegrationTests, PublicKey=0024000004800000940000000602000000240000525341310004000001000100db5f59f098d27276c7833875a6263a3cc74ab17ba9a9df0b52aedbe7252745db7274d5271fd79c1f08f668ecfa8eaab5626fa76adc811d3c8fc55859b0d09d3bc0a84eecd0ba891f2b8a2fc55141cdcc37c2053d53491e650a479967c3622762977900eddbf1252ed08a2413f00a28f3a0752a81203f03ccb7f684db373518b4")]
+[assembly: InternalsVisibleTo("DynamicProxyGenAssembly2, PublicKey=0024000004800000940000000602000000240000525341310004000001000100c547cac37abd99c8db225ef2f6c8a3602f3b3606cc9891605d02baa56104f4cfc0734aa39b93bf7852f7d9266654753cc297e7d2edfe0bac1cdcf9f717241550e0a7b191195b7667bb4f64bcb8e2121380fd1d9d46ad2d92d2d15605093924cceaf74c4861eff62abf69b9291ed0a340e113be11e6a7d3113e92484cf7045cc7")]

src/AWS.Messaging.Lambda/Services/DefaultLambdaMessageProcessor.cs

@@ -337,7 +337,7 @@ public ValueTask ReportMessageFailureAsync(MessageEnvelope message, Cancellation
         return ValueTask.CompletedTask;
     }
 
-    private Message ConvertToStandardSQSMessage(SQSEvent.SQSMessage sqsEventMessage)
+    internal static Message ConvertToStandardSQSMessage(SQSEvent.SQSMessage sqsEventMessage)
     {
         var sqsMessage = new Message
         {
@@ -349,16 +349,19 @@ private Message ConvertToStandardSQSMessage(SQSEvent.SQSMessage sqsEventMessage)
             ReceiptHandle = sqsEventMessage.ReceiptHandle,
         };
 
-        foreach (var attr in sqsEventMessage.MessageAttributes)
+        if (sqsEventMessage.MessageAttributes != null)
         {
-            sqsMessage.MessageAttributes.Add(attr.Key, new MessageAttributeValue
+            foreach (var attr in sqsEventMessage.MessageAttributes)
             {
-                BinaryListValues = attr.Value.BinaryListValues,
-                BinaryValue = attr.Value.BinaryValue,
-                DataType = attr.Value.DataType,
-                StringListValues = attr.Value.StringListValues,
-                StringValue = attr.Value.StringValue,
-            });
+                sqsMessage.MessageAttributes.Add(attr.Key, new MessageAttributeValue
+                {
+                    BinaryListValues = attr.Value.BinaryListValues,
+                    BinaryValue = attr.Value.BinaryValue,
+                    DataType = attr.Value.DataType,
+                    StringListValues = attr.Value.StringListValues,
+                    StringValue = attr.Value.StringValue,
+                });
+            }
         }
 
         return sqsMessage;

test/AWS.Messaging.UnitTests/LambdaTests.cs

@@ -14,10 +14,12 @@
 using AWS.Messaging.Lambda;
 using AWS.Messaging.Serialization;
 using AWS.Messaging.UnitTests.Models;
+using AWS.Messaging.Lambda.Services;
 using Microsoft.Extensions.DependencyInjection;
 using Moq;
 using Xunit;
 using static Amazon.Lambda.SQSEvents.SQSEvent;
+using Amazon;
 
 namespace AWS.Messaging.UnitTests;
 
@@ -312,6 +314,65 @@ await Execute(new SimulatedMessage[] { message4B, message1A, message2A, message5
         Assert.True(message5BPos < message6BPos);
     }
 
+    [Fact]
+    public void ConvertToSDKMessage()
+    {
+        var lambdaMessage = new SQSEvent.SQSMessage
+        {
+            Attributes = new Dictionary<string, string> { { "key", "value" } },
+            Body = "body",
+            Md5OfMessageAttributes = "md5Attributes",
+            MessageId = "messageId",
+            ReceiptHandle = "handle"
+        };
+
+        var sdkMessage = DefaultLambdaMessageProcessor.ConvertToStandardSQSMessage(lambdaMessage);
+
+        Assert.Equal(lambdaMessage.Body, sdkMessage.Body);
+        Assert.Equal(lambdaMessage.Md5OfMessageAttributes, sdkMessage.MD5OfMessageAttributes);
+        Assert.Equal(lambdaMessage.MessageId, sdkMessage.MessageId);
+        Assert.Equal(lambdaMessage.ReceiptHandle, sdkMessage.ReceiptHandle);
+        Assert.True(object.ReferenceEquals(lambdaMessage.Attributes, sdkMessage.Attributes));
+
+        if (AWSConfigs.InitializeCollections)
+        {
+            Assert.Empty(sdkMessage.MessageAttributes);
+        }
+        else
+        {
+            Assert.Null(sdkMessage.MessageAttributes);
+        }
+
+        lambdaMessage.MessageAttributes = new Dictionary<string, MessageAttribute>
+        {
+            {"keyString", new MessageAttribute
+                {
+                    DataType = "String",
+                    StringValue = "TheString"
+                }
+            },
+            {"keyBinary", new MessageAttribute
+                {
+                    DataType = "Binary",
+                    BinaryValue = new System.IO.MemoryStream(new byte[]{1,2,3})
+                }
+            }
+        };
+
+        sdkMessage = DefaultLambdaMessageProcessor.ConvertToStandardSQSMessage(lambdaMessage);
+
+
+        Assert.Equal(lambdaMessage.Body, sdkMessage.Body);
+        Assert.Equal(lambdaMessage.Md5OfMessageAttributes, sdkMessage.MD5OfMessageAttributes);
+        Assert.Equal(lambdaMessage.MessageId, sdkMessage.MessageId);
+        Assert.Equal(lambdaMessage.ReceiptHandle, sdkMessage.ReceiptHandle);
+        Assert.True(object.ReferenceEquals(lambdaMessage.Attributes, sdkMessage.Attributes));
+
+        Assert.Equal(2, sdkMessage.MessageAttributes.Count);
+        Assert.Equal("Binary", sdkMessage.MessageAttributes["keyBinary"].DataType);
+        Assert.Equal(3, sdkMessage.MessageAttributes["keyBinary"].BinaryValue.Length);
+    }
+
     private async Task<string> Execute(SimulatedMessage[] messages, int maxNumberOfConcurrentMessages = 1, bool deleteMessagesWhenCompleted = false, bool addInvalidMessageFormatRecord = false, bool isFifoQueue = false)
     {
         var provider = CreateServiceProvider(maxNumberOfConcurrentMessages: maxNumberOfConcurrentMessages, deleteMessagesWhenCompleted: deleteMessagesWhenCompleted, isFifoQueue: isFifoQueue);