RabbitPublisher: set ContentType and DeliveryMode from Message; add t…

.github/workflows/build-and-publish.yml

@@ -23,6 +23,9 @@ jobs:
 
     - name: Build
       run: dotnet build src --configuration Release --no-restore
+
+    - name: Test
+      run: dotnet test tests/Linn.Common.Messaging.RabbitMQ.Tests --configuration Release
 
     - name: Pack
       if: github.event_name == 'push' && github.ref == 'refs/heads/main'

Linn.Common.Messaging.RabbitMQ.sln

@@ -1,7 +1,7 @@
 
 Microsoft Visual Studio Solution File, Format Version 12.00
 # Visual Studio Version 17
-VisualStudioVersion = 17.12.35506.116 d17.12
+VisualStudioVersion = 17.12.35506.116
 MinimumVisualStudioVersion = 10.0.40219.1
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Linn.Common.Messaging.RabbitMQ", "src\Linn.Common.Messaging.RabbitMQ.csproj", "{C58B1BE7-9DAD-4F3A-AF6E-B9515DE0612B}"
 EndProject
@@ -14,6 +14,12 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution
 		README.md = README.md
 	EndProjectSection
 EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "tests", "tests", "{0AB3BF05-4346-4AA6-1389-037BE0695223}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Linn.Common.Messaging.RabbitMQ.Tests", "tests\Linn.Common.Messaging.RabbitMQ.Tests\Linn.Common.Messaging.RabbitMQ.Tests.csproj", "{5F62DC6D-9E1E-4932-B350-926F444EDAA4}"
+EndProject
+Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{827E0CD3-B72D-47B6-A68D-7590B98EB39B}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -36,8 +42,23 @@ Global
 		{C58B1BE7-9DAD-4F3A-AF6E-B9515DE0612B}.Release|x64.Build.0 = Release|Any CPU
 		{C58B1BE7-9DAD-4F3A-AF6E-B9515DE0612B}.Release|x86.ActiveCfg = Release|Any CPU
 		{C58B1BE7-9DAD-4F3A-AF6E-B9515DE0612B}.Release|x86.Build.0 = Release|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Debug|x64.ActiveCfg = Debug|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Debug|x64.Build.0 = Debug|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Debug|x86.ActiveCfg = Debug|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Debug|x86.Build.0 = Debug|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Release|Any CPU.Build.0 = Release|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Release|x64.ActiveCfg = Release|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Release|x64.Build.0 = Release|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Release|x86.ActiveCfg = Release|Any CPU
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
 	EndGlobalSection
+	GlobalSection(NestedProjects) = preSolution
+		{5F62DC6D-9E1E-4932-B350-926F444EDAA4} = {0AB3BF05-4346-4AA6-1389-037BE0695223}
+	EndGlobalSection
 EndGlobal

README.md

@@ -81,7 +81,7 @@ var publisher = new JsonMessagePublisher<OrderDto>(
 await publisher.PublishAsync(new OrderDto { Id = 42, Total = 99.99m });
 ```
 
-`JsonMessagePublisher<T>` serialises `T` to UTF-8 JSON and sends it to the exchange with the configured routing key. Optional `headers` and `JsonSerializerOptions` can be supplied to the constructor.
+`JsonMessagePublisher<T>` serialises `T` to UTF-8 JSON and sends it to the exchange with the configured routing key. Optional `headers` and `JsonSerializerOptions` can be supplied to the constructor; set the `ContentType` and `Persistent` (delivery mode 2) init properties for those message properties, e.g. `new JsonMessagePublisher<OrderDto>(publisher, "order.created") { ContentType = "application/vnd.example+json", Persistent = true }`. `RabbitPublisher` applies `Message.ContentType` and `Message.DeliveryMode` (2 = persistent, 1 = transient) to the published properties.
 
 ---
 
@@ -194,6 +194,11 @@ var config = new RabbitChannelConfiguration(
 | `headers` | `IReadOnlyDictionary<string, object>?` | `null` | Optional message headers |
 | `serializerOptions` | `JsonSerializerOptions?` | `null` | Custom JSON serialisation options |
 
+| Init property | Type | Default | Description |
+|---|---|---|---|
+| `ContentType` | `string?` | `null` | Content type set on published messages |
+| `Persistent` | `bool` | `false` | Publish with delivery mode 2 (persistent) |
+
 ### `ExchangeBinding`
 
 ```csharp

changelog.md

@@ -1,5 +1,12 @@
 # Changelog
 
+## [6.1.0] - 2026-10-02
+### *Bug Fix*
+- RabbitPublisher now sets ContentType and DeliveryMode from Message (previously ignored). DeliveryMode 2 maps to Persistent, 1 to Transient; null leaves the library default.
+### *Changes*
+- JsonMessagePublisher<T> gains `ContentType` and `Persistent` init properties. The constructor signature is unchanged, so this is binary and source compatible.
+- CI now runs the test project.
+
 ## [6.0.1] - 2026-08-25
 ### *Bug Fix*
 - Remove `x-dead-letter-routing-key` from main queue arguments. Previously set to `""`, this caused RabbitMQ to overwrite the original routing key on dead-letter, making messages unroutable when requeued from the DLQ back to the original exchange. The original routing key is now preserved automatically.

src/JsonMessagePublisher.cs

@@ -2,20 +2,30 @@
 
 namespace Linn.Common.Messaging.RabbitMQ;
 
+// The constructor signature is unchanged since 5.1 (binary compatibility for assemblies compiled
+// against earlier versions); newer options are init properties.
 public class JsonMessagePublisher<T>(
     RabbitPublisher rabbitPublisher,
     string routingKey,
     IReadOnlyDictionary<string, object>? headers = null,
     JsonSerializerOptions? serializerOptions = null)
     : IPublisher<T>
 {
+    /// <summary>Content type set on published messages (e.g. a vendor media type). Default: none.</summary>
+    public string? ContentType { get; init; }
+
+    /// <summary>Publish with delivery mode 2 (persistent). Default: false (broker default).</summary>
+    public bool Persistent { get; init; }
+
     public async Task PublishAsync(T obj, CancellationToken cancellationToken = default)
     {
         var msg = new Message
         {
             RoutingKey = routingKey,
             Body = JsonSerializer.SerializeToUtf8Bytes(obj, serializerOptions),
-            Headers = headers ?? new Dictionary<string, object>()
+            Headers = headers ?? new Dictionary<string, object>(),
+            ContentType = this.ContentType,
+            DeliveryMode = this.Persistent ? 2 : null
         };
 
         await rabbitPublisher.PublishAsync(msg, cancellationToken);

src/Linn.Common.Messaging.RabbitMQ.csproj

@@ -5,7 +5,7 @@
 		<ImplicitUsings>enable</ImplicitUsings>
 		<AssemblyName>Linn.Common.Messaging.RabbitMQ</AssemblyName>
 		<PackageId>Linn.Common.Messaging.RabbitMQ</PackageId>
-		<Version>6.0.1</Version>
+		<Version>6.1.0</Version>
 	  <Nullable>enable</Nullable>
 	</PropertyGroup>
 	<ItemGroup>

src/RabbitMessagePublisher.cs

@@ -12,6 +12,20 @@ public async Task PublishAsync(Message message, CancellationToken cancellationTo
                 ? (IDictionary<string, object?>?)message.Headers : null
         };
 
+        if (message.ContentType != null)
+        {
+            props.ContentType = message.ContentType;
+        }
+
+        if (message.DeliveryMode == 2)
+        {
+            props.DeliveryMode = DeliveryModes.Persistent;
+        }
+        else if (message.DeliveryMode == 1)
+        {
+            props.DeliveryMode = DeliveryModes.Transient;
+        }
+
         await channel.BasicPublishAsync(
             exchange: exchange,
             routingKey: message.RoutingKey,

tests/Linn.Common.Messaging.RabbitMQ.Tests/Linn.Common.Messaging.RabbitMQ.Tests.csproj

@@ -0,0 +1,18 @@
+<Project Sdk="Microsoft.NET.Sdk">
+	<PropertyGroup>
+		<TargetFramework>net10.0</TargetFramework>
+		<ImplicitUsings>enable</ImplicitUsings>
+		<Nullable>enable</Nullable>
+		<IsPackable>false</IsPackable>
+	</PropertyGroup>
+	<ItemGroup>
+		<PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.12.0" />
+		<PackageReference Include="NUnit" Version="4.3.2" />
+		<PackageReference Include="NUnit3TestAdapter" Version="4.6.0" />
+		<PackageReference Include="NSubstitute" Version="5.3.0" />
+		<PackageReference Include="FluentAssertions" Version="7.0.0" />
+	</ItemGroup>
+	<ItemGroup>
+		<ProjectReference Include="..\..\src\Linn.Common.Messaging.RabbitMQ.csproj" />
+	</ItemGroup>
+</Project>

tests/Linn.Common.Messaging.RabbitMQ.Tests/RabbitPublisherTests.cs

@@ -0,0 +1,102 @@
+using System.Text;
+using FluentAssertions;
+using Linn.Common.Messaging.RabbitMQ;
+using NSubstitute;
+using NUnit.Framework;
+using RabbitMQ.Client;
+
+namespace Linn.Common.Messaging.RabbitMQ.Tests;
+
+public class RabbitPublisherTests
+{
+    private IChannel channel = null!;
+    private BasicProperties? captured;
+
+    [SetUp]
+    public void SetUp()
+    {
+        this.channel = Substitute.For<IChannel>();
+        this.captured = null;
+        this.channel.BasicPublishAsync(
+            Arg.Any<string>(),
+            Arg.Any<string>(),
+            Arg.Any<bool>(),
+            Arg.Do<BasicProperties>(p => this.captured = p),
+            Arg.Any<ReadOnlyMemory<byte>>(),
+            Arg.Any<CancellationToken>()).Returns(ValueTask.CompletedTask);
+    }
+
+    private Task Publish(Message m) => new RabbitPublisher(this.channel, "ex").PublishAsync(m);
+
+    private static Message Msg(string? contentType, int? mode) => new()
+    {
+        RoutingKey = "rk",
+        Body = Encoding.UTF8.GetBytes("{}"),
+        ContentType = contentType,
+        DeliveryMode = mode
+    };
+
+    [Test]
+    public async Task ShouldSetContentTypeAndPersistent()
+    {
+        await this.Publish(Msg("application/json", 2));
+        this.captured.Should().NotBeNull();
+        this.captured!.ContentType.Should().Be("application/json");
+        this.captured.DeliveryMode.Should().Be(DeliveryModes.Persistent);
+    }
+
+    [Test]
+    public async Task ShouldSetTransient()
+    {
+        await this.Publish(Msg(null, 1));
+        this.captured!.DeliveryMode.Should().Be(DeliveryModes.Transient);
+    }
+
+    [Test]
+    public async Task ShouldLeaveUnsetWhenNull()
+    {
+        await this.Publish(Msg(null, null));
+        this.captured!.ContentType.Should().BeNull();
+        this.captured.IsDeliveryModePresent().Should().BeFalse();
+        this.captured.IsContentTypePresent().Should().BeFalse();
+    }
+
+    [Test]
+    public async Task ShouldKeepHeaders()
+    {
+        var m = new Message
+        {
+            RoutingKey = "rk",
+            Headers = new Dictionary<string, object> { ["a"] = "b" }
+        };
+        await this.Publish(m);
+        this.captured!.Headers.Should().ContainKey("a");
+    }
+
+    [Test]
+    public async Task JsonPublisherPassesContentTypeAndPersistence()
+    {
+        var p = new JsonMessagePublisher<string>(new RabbitPublisher(this.channel, "ex"), "rk")
+                    {
+                        ContentType = "application/json",
+                        Persistent = true
+                    };
+        await p.PublishAsync("x");
+        this.captured!.ContentType.Should().Be("application/json");
+        this.captured.DeliveryMode.Should().Be(DeliveryModes.Persistent);
+    }
+
+    // Binary compatibility: assemblies compiled against 5.1-6.0 call this exact constructor.
+    [Test]
+    public void JsonPublisherKeepsItsOriginalConstructorSignature()
+    {
+        var ctor = typeof(JsonMessagePublisher<string>).GetConstructor(
+            new[]
+                {
+                    typeof(RabbitPublisher), typeof(string), typeof(IReadOnlyDictionary<string, object>),
+                    typeof(System.Text.Json.JsonSerializerOptions)
+                });
+        ctor.Should().NotBeNull();
+        typeof(JsonMessagePublisher<string>).GetConstructors().Should().HaveCount(1);
+    }
+}