Perform a stable sort on CoapMessage.Options

Fixes #11

Author: NZSmartie

src/CoAPNet/CoapMessage.cs

@@ -166,8 +166,7 @@ public List<CoapOption> Options
             get { return _options; }
             set
             {
-                _options = value;
-                _options.Sort();
+                _options = value.OrderBy(o => o.OptionNumber).ToList();
             }
         }
 
@@ -244,8 +243,7 @@ public byte[] ToBytes()
             // +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
             var currentOptionDelta = 0;
 
-            _options.Sort();
-            foreach (var option in _options)
+            foreach (var option in _options.OrderBy(o => o.OptionNumber))
             {
                 var optionHeader = new List<byte>();
                 int optionDelta = option.OptionNumber - currentOptionDelta;

src/CoAPNet/CoapOptions.cs

@@ -132,7 +132,7 @@ public static bool Contains(this ICollection<CoapOption> collection, int optionN
     /// <summary>
     /// Repressents a CoAP-Option (Much like HTTP Headers) that may be present in a <see cref="CoapMessage"/>.
     /// </summary>
-    public class CoapOption : IComparable<CoapOption>
+    public class CoapOption
     {
         private readonly int _optionNumber;
         /// <summary>
@@ -471,10 +471,5 @@ public override int GetHashCode()
 
             return hashcode;
         }
-
-        int IComparable<CoapOption>.CompareTo(CoapOption other)
-        {
-            return _optionNumber - other._optionNumber;
-        }
     }
 }

tests/CoAPNet.Tests/CoapMessageTest.cs

@@ -232,22 +232,24 @@ public void TestMessageOptionsOutOfOrder()
                 new Options.UriHost("example.net"),
                 new Options.UriPath(".well-known"),
                 new Options.UriPath("core"),
+                new Options.ContentFormat(Options.ContentFormatType.ApplicationJson),
                 new Options.Accept(Options.ContentFormatType.ApplicationLinkFormat),
             };
 
             // Act
             _message = new CoapMessage
             {
                 Options = new List<CoapOption> {
-                    new Options.Accept(Options.ContentFormatType.ApplicationLinkFormat),
+                    new Options.Accept(Options.ContentFormatType.ApplicationJson),
                     new Options.UriPath(".well-known"),
                     new Options.UriPath("core"),
                     new Options.UriHost("example.net"),
+                    new Options.ContentFormat(Options.ContentFormatType.ApplicationJson),
                 }
             };
 
             // Assert
-            Assert.IsTrue(expectedOptions.SequenceEqual(_message.Options));
+            Assert.That(_message.Options, Is.EqualTo(expectedOptions));
         }
 
         [Test]