Fix file comment serialization

SaneTsv/SaneTsvTest/Program.cs

@@ -759,6 +759,30 @@ internal class Program : SaneTsv
       }
     }
 
+    {
+      string testName = "File comment serde";
+
+      string testString1 = "#this is a file comment" +
+        "\n# and one more line since you're such a good customer" +
+        "\ncolumn1:type:boolean\tcolumn2:binary\tcolumnthree\\nyep:string" +
+        "\nTRUE\tvalue\\\\t\0woo\tvaluetrhee" +
+        "\nFALSE\tnother\tno\\ther";
+
+
+      CommentedTsv<BoolTestRecord2> parsed = SaneTsv.ParseCommentedTsv<BoolTestRecord2>(Encoding.UTF8.GetBytes(testString1));
+
+      string reserialized = Encoding.UTF8.GetString(SaneTsv.SerializeCommentedTsv<BoolTestRecord2>(parsed.Records, parsed.FileComment));
+
+      if (reserialized == testString1)
+      {
+        Console.WriteLine($"Passed {testName}");
+      }
+      else
+      {
+        Console.WriteLine($"Failed {testName}");
+      }
+    }
+
     Console.WriteLine("Done with tests");
   }
 }