improvement: Out of band jobs with generic message types now also output the names of the generic arguments

Author: jhartmann123

src/Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <Version>9.5.2</Version>
+    <Version>9.5.3</Version>
     <TargetFramework>net8.0</TargetFramework>
   </PropertyGroup>
 

src/Hangfire/src/MediatorHandlerContext.cs

@@ -14,7 +14,7 @@ public MediatorHandlerContext(object message, string handlerType)
         HandlerType = handlerType;
 
         var type = Message.GetType();
-        DisplayName = $"Message: {type.Name} ({type.Namespace})";
+        DisplayName = $"Message: {GetTypeName(type)} ({type.Namespace})";
     }
 
     public object Message { get; set; }
@@ -26,6 +26,20 @@ public MediatorHandlerContext(object message, string handlerType)
 
     public override string ToString() => DisplayName;
 
+    private string GetTypeName(Type type)
+    {
+        if (!type.IsGenericType)
+            return type.Name;
+
+        // Remove the `n suffix from generic type names (e.g. List`1 -> List)
+        var index = type.Name.IndexOf('`', StringComparison.Ordinal);
+        var typeName = index > 0 ? type.Name[..index] : type.Name;
+
+        var genericNames = string.Join(", ", type.GetGenericArguments().Select(GetTypeName));
+
+        return $"{typeName}<{genericNames}>";
+    }
+
     public class HangfireUser(List<HangfireUser.HangfireUserClaim> claims)
     {
         public List<HangfireUserClaim> Claims { get; } = claims;

src/Hangfire/test/MediatorHandlerContextTests.cs

@@ -0,0 +1,33 @@
+// Copyright (c) Fusonic GmbH. All rights reserved.
+// Licensed under the MIT License. See LICENSE file in the project root for license information.
+
+using FluentAssertions;
+using Xunit;
+
+namespace Fusonic.Extensions.Hangfire.Tests;
+
+public class MediatorHandlerContextTests
+{
+    [Theory]
+    [InlineData(typeof(int), "Message: Int32 (System)")]
+    [InlineData(typeof(List<int>), "Message: List<Int32> (System.Collections.Generic)")]
+    [InlineData(typeof(List<List<int>>), "Message: List<List<Int32>> (System.Collections.Generic)")]
+    [InlineData(typeof(List<List<List<int>>>), "Message: List<List<List<Int32>>> (System.Collections.Generic)")]
+    public void DisplayName_ContainsMessageType_WithFriendlyGenericArgs(Type type, string expectedString)
+    {
+        var message = Activator.CreateInstance(type)!;
+        var context = new MediatorHandlerContext(message, "HandlerType");
+
+        context.DisplayName.Should().Be(expectedString);
+    }
+
+    [Fact]
+    public void ToString_ReturnsDisplayName()
+    {
+        var context= new MediatorHandlerContext(new object(), "HandlerType");
+        context.ToString().Should().Be("Message: Object (System)");
+
+        context.DisplayName = "Hallo";
+        context.ToString().Should().Be("Hallo");
+    }
+}