Fix SkipSerialization leak (#6361)

src/NServiceBus.AcceptanceTests/Core/Pipeline/When_skipping_serialization_with_nested_send.cs

@@ -0,0 +1,113 @@
+namespace NServiceBus.AcceptanceTests.Core.Pipeline
+{
+    using System;
+    using System.Threading.Tasks;
+    using AcceptanceTesting;
+    using AcceptanceTesting.Customization;
+    using EndpointTemplates;
+    using NServiceBus.Pipeline;
+    using NUnit.Framework;
+
+    public class When_skipping_serialization_with_nested_send : NServiceBusAcceptanceTest
+    {
+        [Test]
+        public async Task Should_not_skip_serialization_for_nested_send()
+        {
+            var context = await Scenario.Define<Context>()
+                .WithEndpoint<Sender>(e => e
+                    .When(s => s.Send(new MessageWithoutSerialization { SomeProperty = "Some property value" })))
+                .WithEndpoint<Receiver>()
+                .Done(c => c.NestedMessageReceived)
+                .Run(TimeSpan.FromSeconds(15));
+
+            Assert.IsTrue(context.NestedMessageReceived, "the serialization should the nested message should not be skipped");
+            Assert.AreEqual("Some property value for NestedMessage", context.NestedMessagePropertyValue, "the message sould be correctly serialized");
+            Assert.IsFalse(context.MessageWithSkippedSerializationReceived, "NServiceBus should discard messages without a body");
+        }
+
+        class Context : ScenarioContext
+        {
+            public bool MessageWithSkippedSerializationReceived { get; set; }
+            public bool NestedMessageReceived { get; set; }
+            public string NestedMessagePropertyValue { get; set; }
+        }
+
+        class Sender : EndpointConfigurationBuilder
+        {
+            public Sender()
+            {
+                EndpointSetup<DefaultServer>(c =>
+                {
+                    c.ConfigureTransport().Routing().RouteToEndpoint(typeof(NestedMessage).Assembly, Conventions.EndpointNamingConvention(typeof(Receiver)));
+                    c.Pipeline.Register(new SkipSerializationBehavior(), $"Skips serialization for {nameof(MessageWithoutSerialization)}");
+                    c.Pipeline.Register(new NestedSendBehavior(), $"Sends a {nameof(NestedMessage)} from the outgoing pipeline");
+                });
+            }
+
+            class SkipSerializationBehavior : Behavior<IOutgoingLogicalMessageContext>
+            {
+                public override Task Invoke(IOutgoingLogicalMessageContext context, Func<Task> next)
+                {
+                    if (context.Message.MessageType == typeof(MessageWithoutSerialization))
+                    {
+                        context.SkipSerialization();
+                    }
+
+                    return next();
+                }
+            }
+
+            class NestedSendBehavior : Behavior<IOutgoingPhysicalMessageContext>
+            {
+                public override async Task Invoke(IOutgoingPhysicalMessageContext context, Func<Task> next)
+                {
+                    var logicalMessage = context.Extensions.Get<OutgoingLogicalMessage>();
+                    if (logicalMessage.MessageType != typeof(NestedMessage))
+                    {
+                        await context.Send(new NestedMessage { SomeProperty = "Some property value for NestedMessage" });
+                    }
+
+                    await next();
+                }
+            }
+        }
+
+        class Receiver : EndpointConfigurationBuilder
+        {
+            public Receiver() => EndpointSetup<DefaultServer>();
+
+            class MessageHandler : IHandleMessages<MessageWithoutSerialization>, IHandleMessages<NestedMessage>
+            {
+                Context testContext;
+
+                public MessageHandler(Context testContext)
+                {
+                    this.testContext = testContext;
+                }
+
+                public Task Handle(MessageWithoutSerialization message, IMessageHandlerContext context)
+                {
+                    testContext.MessageWithSkippedSerializationReceived = true;
+                    return Task.FromResult(0);
+                }
+
+                public Task Handle(NestedMessage message, IMessageHandlerContext context)
+                {
+                    testContext.NestedMessageReceived = true;
+                    testContext.NestedMessagePropertyValue = message.SomeProperty;
+                    return Task.FromResult(0);
+                }
+            }
+        }
+
+        public class MessageWithoutSerialization : IMessage
+        {
+            public string SomeProperty { get; set; }
+        }
+
+        public class NestedMessage : IMessage
+        {
+            public string SomeProperty { get; set; }
+        }
+    }
+}

src/NServiceBus.Core/Serialization/SerializationContextExtensions.cs

@@ -18,7 +18,9 @@ public static class SerializationContextExtensions
         public static void SkipSerialization(this IOutgoingLogicalMessageContext context)
         {
             Guard.AgainstNull(nameof(context), context);
-            context.Extensions.Set("MessageSerialization.Skip", true);
+
+            // Prefix the setting key with the current message id to prevent the setting from leaking to nested send operations for different messages
+            context.Extensions.Set($"{context.MessageId}:MessageSerialization.Skip", true);
         }
 
         /// <summary>
@@ -27,7 +29,7 @@ public static void SkipSerialization(this IOutgoingLogicalMessageContext context
         public static bool ShouldSkipSerialization(this IOutgoingLogicalMessageContext context)
         {
             Guard.AgainstNull(nameof(context), context);
-            if (context.Extensions.TryGet("MessageSerialization.Skip", out bool shouldSkipSerialization))
+            if (context.Extensions.TryGet($"{context.MessageId}:MessageSerialization.Skip", out bool shouldSkipSerialization))
             {
                 return shouldSkipSerialization;
             }