Remove JsonSerializerOptions copy in ProblemDetailsJsonOptionsSetup (#46716)

* Remove JsonSerializerOptions copy in ProblemDetailsJsonOptionsSetup

* Adding comments

* Update src/Http/Http.Extensions/test/ProblemDetailsServiceCollectionExtensionsTest.cs

Co-authored-by: Brennan <[email protected]>

---------

Co-authored-by: Brennan <[email protected]>

Author: brunolins16

src/Http/Http.Extensions/src/ProblemDetailsJsonOptionsSetup.cs

@@ -11,15 +11,23 @@ internal sealed class ProblemDetailsJsonOptionsSetup : IPostConfigureOptions<Jso
 {
     public void PostConfigure(string? name, JsonOptions options)
     {
-        if (options.SerializerOptions.TypeInfoResolver is not null)
+        switch (options.SerializerOptions.TypeInfoResolver)
         {
-            if (options.SerializerOptions.IsReadOnly)
-            {
-                options.SerializerOptions = new(options.SerializerOptions);
-            }
-
-            // Combine the current resolver with our internal problem details context
-            options.SerializerOptions.TypeInfoResolver = JsonTypeInfoResolver.Combine(options.SerializerOptions.TypeInfoResolver!, ProblemDetailsJsonContext.Default);
+            case DefaultJsonTypeInfoResolver:
+                // In this case, the current configuration is using a reflection-based resolver
+                // and we are prepending our internal problem details context to be evaluated
+                // first.
+                options.SerializerOptions.TypeInfoResolver = JsonTypeInfoResolver.Combine(ProblemDetailsJsonContext.Default, options.SerializerOptions.TypeInfoResolver);
+                break;
+            case not null:
+                // Combine the current resolver with our internal problem details context (adding last)
+                options.SerializerOptions.AddContext<ProblemDetailsJsonContext>();
+                break;
+            default:
+                // Not adding our source gen context when TypeInfoResolver == null
+                // since adding it will skip the reflection-based resolver and potentially
+                // cause unexpected serialization problems
+                break;
         }
     }
 }

src/Http/Http.Extensions/test/ProblemDetailsServiceCollectionExtensionsTest.cs

@@ -2,6 +2,7 @@
 // The .NET Foundation licenses this file to you under the MIT license.
 
 using System.Text.Json.Serialization;
+using System.Text.Json.Serialization.Metadata;
 using Microsoft.AspNetCore.Http.Json;
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.Extensions.DependencyInjection;
@@ -103,7 +104,7 @@ public void AddProblemDetails_CombinesProblemDetailsContext()
     }
 
     [Fact]
-    public void AddProblemDetails_CombinesProblemDetailsContext_ForReadOnlyJsonOptions()
+    public void AddProblemDetails_Throws_ForReadOnlyJsonOptions()
     {
         // Arrange
         var collection = new ServiceCollection();
@@ -120,10 +121,7 @@ public void AddProblemDetails_CombinesProblemDetailsContext_ForReadOnlyJsonOptio
         var services = collection.BuildServiceProvider();
         var jsonOptions = services.GetService<IOptions<JsonOptions>>();
 
-        Assert.NotNull(jsonOptions.Value);
-        Assert.NotNull(jsonOptions.Value.SerializerOptions.TypeInfoResolver);
-        Assert.NotNull(jsonOptions.Value.SerializerOptions.TypeInfoResolver.GetTypeInfo(typeof(ProblemDetails), jsonOptions.Value.SerializerOptions));
-        Assert.NotNull(jsonOptions.Value.SerializerOptions.TypeInfoResolver.GetTypeInfo(typeof(TypeA), jsonOptions.Value.SerializerOptions));
+        Assert.Throws<InvalidOperationException>(() => jsonOptions.Value);
     }
 
     [Fact]
@@ -166,6 +164,28 @@ public void AddProblemDetails_DoesNotCombineProblemDetailsContext_WhenNullTypeIn
         Assert.Null(jsonOptions.Value.SerializerOptions.TypeInfoResolver);
     }
 
+    [Fact]
+    public void AddProblemDetails_CombineProblemDetailsContext_WhenDefaultTypeInfoResolver()
+    {
+        // Arrange
+        var collection = new ServiceCollection();
+        collection.AddOptions<JsonOptions>();
+        collection.ConfigureAll<JsonOptions>(options => options.SerializerOptions.TypeInfoResolver = new DefaultJsonTypeInfoResolver());
+
+        // Act
+        collection.AddProblemDetails();
+
+        // Assert
+        var services = collection.BuildServiceProvider();
+        var jsonOptions = services.GetService<IOptions<JsonOptions>>();
+
+        Assert.NotNull(jsonOptions.Value);
+        Assert.NotNull(jsonOptions.Value.SerializerOptions.TypeInfoResolver);
+        Assert.IsNotType<DefaultJsonTypeInfoResolver>(jsonOptions.Value.SerializerOptions.TypeInfoResolver);
+        Assert.NotNull(jsonOptions.Value.SerializerOptions.TypeInfoResolver.GetTypeInfo(typeof(ProblemDetails), jsonOptions.Value.SerializerOptions));
+        Assert.NotNull(jsonOptions.Value.SerializerOptions.TypeInfoResolver.GetTypeInfo(typeof(TypeA), jsonOptions.Value.SerializerOptions));
+    }
+
     [JsonSerializable(typeof(TypeA))]
     internal partial class TestExtensionsJsonContext : JsonSerializerContext
     { }