Refactor the comments functionality

YamlDotNet.Test/Serialization/YamlCommentTests.cs

@@ -23,7 +23,9 @@ public void SerializationWithComment()
             Serializer serializer = new Serializer();
             string result = serializer.Serialize(person);
 
-            Output.WriteLine(result);
+            Assert.Contains("# this is a yaml comment about name property", result);
+            Assert.Contains("# this is age", result);
+            Assert.Contains("# male or female", result);
         }
 
         class Person

YamlDotNet/Serialization/ObjectGraphVisitors/CommentsObjectGraphVisitor.cs

@@ -0,0 +1,50 @@
+//  This file is part of YamlDotNet - A .NET library for YAML.
+//  Copyright (c) Antoine Aubry and contributors
+
+//  Permission is hereby granted, free of charge, to any person obtaining a copy of
+//  this software and associated documentation files (the "Software"), to deal in
+//  the Software without restriction, including without limitation the rights to
+//  use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
+//  of the Software, and to permit persons to whom the Software is furnished to do
+//  so, subject to the following conditions:
+
+//  The above copyright notice and this permission notice shall be included in all
+//  copies or substantial portions of the Software.
+
+//  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+//  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+//  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+//  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+//  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+//  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+//  SOFTWARE.
+
+using System;
+using YamlDotNet.Core;
+
+namespace YamlDotNet.Serialization.ObjectGraphVisitors
+{
+    public sealed class CommentsObjectGraphVisitor : ChainedObjectGraphVisitor
+    {
+        public CommentsObjectGraphVisitor(IObjectGraphVisitor<IEmitter> nextVisitor)
+            : base(nextVisitor)
+        {
+        }
+
+        private static object? GetDefault(Type type)
+        {
+            return type.IsValueType() ? Activator.CreateInstance(type) : null;
+        }
+
+        public override bool EnterMapping(IPropertyDescriptor key, IObjectDescriptor value, IEmitter context)
+        {
+            var yamlMember = key.GetCustomAttribute<YamlMemberAttribute>();
+            if (yamlMember?.Description != null)
+            {
+                context.Emit(new Core.Events.Comment(yamlMember.Description, false));
+            }
+
+            return base.EnterMapping(key, value, context);
+        }
+    }
+}

YamlDotNet/Serialization/ObjectGraphVisitors/DefaultValuesObjectGraphVisitor.cs

@@ -67,14 +67,6 @@ public override bool EnterMapping(IPropertyDescriptor key, IObjectDescriptor val
                     break;
             }
 
-            if (yamlMember != null)
-            {
-                if (yamlMember.Description != null)
-                {
-                    context.Emit(new Core.Events.Comment(yamlMember.Description, false));
-                }
-            }
-
             return base.EnterMapping(key, value, context);
         }
     }

YamlDotNet/Serialization/SerializerBuilder.cs

@@ -76,6 +76,10 @@ public SerializerBuilder()
                 {
                     typeof(DefaultValuesObjectGraphVisitor),
                     args => new DefaultValuesObjectGraphVisitor(defaultValuesHandlingConfiguration, args.InnerVisitor)
+                },
+                {
+                    typeof(CommentsObjectGraphVisitor),
+                    args => new CommentsObjectGraphVisitor(args.InnerVisitor)
                 }
             };