Tweak AgentAbstractionsJsonUtilities to better match AIJsonUtilities (#1094)

Functional change includes setting the encoder used by the options and employing JsonStringEnumConverter.

dotnet/src/Microsoft.Agents.AI.Abstractions/AgentAbstractionsJsonUtilities.cs

@@ -1,6 +1,7 @@
 // Copyright (c) Microsoft. All rights reserved.
 
 using System.Diagnostics.CodeAnalysis;
+using System.Text.Encodings.Web;
 using System.Text.Json;
 using System.Text.Json.Serialization;
 using Microsoft.Extensions.AI;
@@ -26,6 +27,10 @@ public static partial class AgentAbstractionsJsonUtilities
     /// <item>Enables <see cref="JsonSerializerDefaults.Web"/> defaults.</item>
     /// <item>Enables <see cref="JsonIgnoreCondition.WhenWritingNull"/> as the default ignore condition for properties.</item>
     /// <item>Enables <see cref="JsonNumberHandling.AllowReadingFromString"/> as the default number handling for number types.</item>
+    /// <item>
+    /// Enables <see cref="JavaScriptEncoder.UnsafeRelaxedJsonEscaping"/> when escaping JSON strings.
+    /// Consuming applications must ensure that JSON outputs are adequately escaped before embedding in other document formats, such as HTML and XML.
+    /// </item>
     /// </list>
     /// </para>
     /// </remarks>
@@ -40,17 +45,28 @@ public static partial class AgentAbstractionsJsonUtilities
     private static JsonSerializerOptions CreateDefaultOptions()
     {
         // Copy the configuration from the source generated context.
-        JsonSerializerOptions options = new(JsonContext.Default.Options);
+        JsonSerializerOptions options = new(JsonContext.Default.Options)
+        {
+            Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping, // same as AIJsonUtilities
+        };
 
         // Chain with all supported types from Microsoft.Extensions.AI.Abstractions.
+        // If reflection-based serialization is enabled by default, this includes
+        // the default type info resolver that utilizes reflection, but we need to manually
+        // apply the same converter AIJsonUtilities adds for string-based enum serialization,
+        // as that's not propagated as part of the resolver.
         options.TypeInfoResolverChain.Add(AIJsonUtilities.DefaultOptions.TypeInfoResolver!);
+        if (JsonSerializer.IsReflectionEnabledByDefault)
+        {
+            options.Converters.Add(new JsonStringEnumConverter());
+        }
 
         options.MakeReadOnly();
         return options;
     }
 
-    // Keep in sync with CreateDefaultOptions above.
     [JsonSourceGenerationOptions(JsonSerializerDefaults.Web,
+        UseStringEnumConverter = true,
         DefaultIgnoreCondition = JsonIgnoreCondition.WhenWritingNull,
         NumberHandling = JsonNumberHandling.AllowReadingFromString)]
 
@@ -65,5 +81,5 @@ public static partial class AgentAbstractionsJsonUtilities
     [JsonSerializable(typeof(InMemoryChatMessageStore.StoreState))]
 
     [ExcludeFromCodeCoverage]
-    internal sealed partial class JsonContext : JsonSerializerContext;
+    private sealed partial class JsonContext : JsonSerializerContext;
 }

dotnet/tests/Microsoft.Agents.AI.Abstractions.UnitTests/AgentAbstractionsJsonUtilitiesTests.cs

@@ -0,0 +1,91 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Text.Encodings.Web;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+using Microsoft.Extensions.AI;
+
+#pragma warning disable CA1812 // Avoid uninstantiated internal classes
+
+namespace Microsoft.Agents.AI.Abstractions.UnitTests;
+
+/// <summary>
+/// Tests for <see cref="AgentAbstractionsJsonUtilities"/>
+/// </summary>
+public class AgentAbstractionsJsonUtilitiesTests
+{
+    [Fact]
+    public void DefaultOptions_HasExpectedConfiguration()
+    {
+        var options = AgentAbstractionsJsonUtilities.DefaultOptions;
+
+        // Must be read-only singleton.
+        Assert.NotNull(options);
+        Assert.Same(options, AgentAbstractionsJsonUtilities.DefaultOptions);
+        Assert.True(options.IsReadOnly);
+
+        // Must conform to JsonSerializerDefaults.Web
+        Assert.Equal(JsonNamingPolicy.CamelCase, options.PropertyNamingPolicy);
+        Assert.True(options.PropertyNameCaseInsensitive);
+        Assert.Equal(JsonNumberHandling.AllowReadingFromString, options.NumberHandling);
+
+        // Additional settings
+        Assert.Equal(JsonIgnoreCondition.WhenWritingNull, options.DefaultIgnoreCondition);
+        Assert.Same(JavaScriptEncoder.UnsafeRelaxedJsonEscaping, options.Encoder);
+    }
+
+    [Theory]
+    [InlineData("<script>alert('XSS')</script>", "<script>alert('XSS')</script>")]
+    [InlineData("""{"forecast":"sunny", "temperature":"75"}""", """{\"forecast\":\"sunny\", \"temperature\":\"75\"}""")]
+    [InlineData("""{"message":"Πάντα ῥεῖ."}""", """{\"message\":\"Πάντα ῥεῖ.\"}""")]
+    [InlineData("""{"message":"七転び八起き"}""", """{\"message\":\"七転び八起き\"}""")]
+    [InlineData("""☺️🤖🌍𝄞""", """☺️\uD83E\uDD16\uD83C\uDF0D\uD834\uDD1E""")]
+    public void DefaultOptions_UsesExpectedEscaping(string input, string expectedJsonString)
+    {
+        var options = AgentAbstractionsJsonUtilities.DefaultOptions;
+        string json = JsonSerializer.Serialize(input, options);
+        Assert.Equal($@"""{expectedJsonString}""", json);
+    }
+
+    [Fact]
+    public void DefaultOptions_UsesReflectionWhenDefault()
+    {
+        Type anonType = new { Name = 42 }.GetType();
+        Assert.Equal(JsonSerializer.IsReflectionEnabledByDefault, AgentAbstractionsJsonUtilities.DefaultOptions.TryGetTypeInfo(anonType, out _));
+    }
+
+    [Fact]
+    public void DefaultOptions_AllowsReadingNumbersFromStrings_AndOmitsNulls()
+    {
+        var obj = JsonSerializer.Deserialize<NumberContainer>(
+            "{\"value\":\"42\",\"optional\":null}", // value as string, optional null
+            AgentAbstractionsJsonUtilities.DefaultOptions);
+        Assert.NotNull(obj);
+        Assert.Equal(42, obj!.Value);
+        Assert.Null(obj.Optional);
+        Assert.Equal("{\"value\":42}",
+            JsonSerializer.Serialize(obj, AgentAbstractionsJsonUtilities.DefaultOptions)); // null omitted
+    }
+
+    [Fact]
+    public void DefaultOptions_SerializesEnumsAsStrings()
+    {
+        Assert.Equal("\"Monday\"", JsonSerializer.Serialize(DayOfWeek.Monday, AgentAbstractionsJsonUtilities.DefaultOptions));
+    }
+
+    [Fact]
+    public void DefaultOptions_UsesCamelCasePropertyNames_ForAgentRunResponse()
+    {
+        var response = new AgentRunResponse(new ChatMessage(ChatRole.Assistant, "Hello"));
+        string json = JsonSerializer.Serialize(response, AgentAbstractionsJsonUtilities.DefaultOptions);
+        Assert.Contains("\"messages\"", json);
+        Assert.DoesNotContain("\"Messages\"", json);
+    }
+
+    private sealed class NumberContainer
+    {
+        public int Value { get; set; }
+        public string? Optional { get; set; }
+    }
+}