Add testcase for #61734

src/libraries/System.Text.Json/gen/JsonSourceGenerator.Emitter.cs

@@ -152,6 +152,7 @@ private void AddSource(string fileName, string source, bool isRootContextDef = f
                 bool isInGlobalNamespace = @namespace == JsonConstants.GlobalNamespaceValue;
 
                 StringBuilder sb = new(@"// <auto-generated/>
+
 #nullable enable annotations
 #nullable disable warnings
 

src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Tests/JsonSerializerContextTests.cs

@@ -395,6 +395,22 @@ public static void ClassWithStringValuesRoundtrips()
             Assert.Equal("""{"StringValuesProperty":["abc","def"]}""", json);
         }
 
+        // Regression test for https://github.com/dotnet/runtime/issues/61734
+        [Fact]
+        public static void ClassWithDictionaryPropertyRoundtrips()
+        {
+            JsonSerializerOptions options = ClassWithDictionaryPropertyContext.Default.Options;
+
+            ClassWithDictionaryProperty obj = new(new Dictionary<string, object?>()
+            {
+                ["foo"] = "bar",
+                ["test"] = "baz",
+            });
+
+            string json = JsonSerializer.Serialize(obj, options);
+            Assert.Equal("""{"DictionaryProperty":{"foo":"bar","test":"baz"}}""", json);
+        }
+
         [JsonConverter(typeof(JsonStringEnumConverter))]
         public enum TestEnum
         {
@@ -416,6 +432,11 @@ internal partial class ClassWithStringValuesContext : JsonSerializerContext
         {
         }
 
+        [JsonSerializable(typeof(ClassWithDictionaryProperty))]
+        internal partial class ClassWithDictionaryPropertyContext : JsonSerializerContext
+        {
+        }
+
         internal class ClassWithPocoListDictionaryAndNullable
         {
             public uint UIntProperty { get; set; }

src/libraries/System.Text.Json/tests/System.Text.Json.SourceGeneration.Tests/TestClasses.cs

@@ -281,4 +281,10 @@ public sealed class ClassWithStringValues
     {
         public StringValues StringValuesProperty { get; set; }
     }
+
+    public class ClassWithDictionaryProperty
+    {
+        public ClassWithDictionaryProperty(Dictionary<string, object?> property) => DictionaryProperty = property;
+        public Dictionary<string, object?> DictionaryProperty { get; }
+    }
 }