public void Can_serialize_nullable_enum_with_turned_on_TreatEnumAsInteger() { JsConfig.TreatEnumAsInteger = true; var anon = new ClassWithNullableEnumWithoutFlagsAttribute { EnumProp1 = ExampleEnumWithoutFlagsAttribute.One }; Assert.That(JsonSerializer.SerializeToString(anon), Is.EqualTo("{\"EnumProp1\":1}")); }