fix: serialization using IndentedTextWriter causes missing indentation

YamlDotNet.Test/Serialization/SerializationTests.cs

@@ -20,6 +20,7 @@
 // SOFTWARE.
 
 using System;
+using System.CodeDom.Compiler;
 using System.Collections;
 using System.Collections.Concurrent;
 using System.Collections.Generic;
@@ -329,6 +330,35 @@ public void SerializeWithCRNewLine()
             result.Should().Be(expectedResult);
         }
 
+
+        /// <summary>
+        /// Tests the serialization of a dictionary containing a list of strings using IndentedTextWriter.
+        /// </summary>
+        [Fact]
+        public void SerializeWithTabs()
+        {
+            var tabString = " ";
+            using var writer = new StringWriter();
+            using var indentedTextWriter = new IndentedTextWriter(writer, tabString) { Indent = 2 };
+
+            //create a dictionary with a list of strings to test the tabbed serialization
+            var items = new List<string> { "item 1", "item 2" };
+            var list = new Dictionary<string, List<string>> { { "key", items } };
+
+            SerializerBuilder
+                .Build()
+                .Serialize(indentedTextWriter, list);
+
+            //split serialized output into lines
+            var lines = indentedTextWriter.InnerWriter.ToString().Split(new[] { Environment.NewLine }, StringSplitOptions.None);
+
+            //expected indentation
+            var indent = string.Join(string.Empty, Enumerable.Repeat(tabString, indentedTextWriter.Indent).ToList());
+
+            //check that the serialized lines (excluding the first and last) start with the expected indentation
+            lines.Skip(1).Take(lines.Length - 2).Where(element => element.StartsWith(indent)).Should().HaveCount(items.Count);
+        }
+
         [Fact]
         public void DeserializeExplicitType()
         {

YamlDotNet/Core/Emitter.cs

@@ -67,7 +67,6 @@ public class Emitter : IEmitter
         private bool isIndentation;
         private readonly bool forceIndentLess;
         private readonly bool useUtf16SurrogatePair;
-        private readonly string newLine;
 
         private bool isDocumentEndWritten;
 
@@ -150,9 +149,9 @@ public Emitter(TextWriter output, EmitterSettings settings)
             this.skipAnchorName = settings.SkipAnchorName;
             this.forceIndentLess = !settings.IndentSequences;
             this.useUtf16SurrogatePair = settings.UseUtf16SurrogatePairs;
-            this.newLine = settings.NewLine;
 
             this.output = output;
+            this.output.NewLine = settings.NewLine;
             this.outputUsesUnicodeEncoding = IsUnicode(output.Encoding);
         }
 
@@ -1937,7 +1936,7 @@ private void WriteBreak(char breakCharacter = '\n')
         {
             if (breakCharacter == '\n')
             {
-                output.Write(newLine);
+                output.WriteLine();
             }
             else
             {