Improve topic comparer.

Tests/MQTTnet.Benchmarks/TopicFilterComparerBenchmark.cs

@@ -37,13 +37,13 @@ namespace MQTTnet.Benchmarks
         {
             for (var i = 0; i < 10000; i++)
             {
-                MqttTopicFilterComparer.IsMatch("sport/tennis/player1", "sport/#");
-                MqttTopicFilterComparer.IsMatch("sport/tennis/player1/ranking", "sport/#/ranking");
-                MqttTopicFilterComparer.IsMatch("sport/tennis/player1/score/wimbledon", "sport/+/player1/#");
-                MqttTopicFilterComparer.IsMatch("sport/tennis/player1", "sport/tennis/+");
-                MqttTopicFilterComparer.IsMatch("/finance", "+/+");
-                MqttTopicFilterComparer.IsMatch("/finance", "/+");
-                MqttTopicFilterComparer.IsMatch("/finance", "+");
+                MqttTopicFilterComparer.Compare("sport/tennis/player1", "sport/#");
+                MqttTopicFilterComparer.Compare("sport/tennis/player1/ranking", "sport/#/ranking");
+                MqttTopicFilterComparer.Compare("sport/tennis/player1/score/wimbledon", "sport/+/player1/#");
+                MqttTopicFilterComparer.Compare("sport/tennis/player1", "sport/tennis/+");
+                MqttTopicFilterComparer.Compare("/finance", "+/+");
+                MqttTopicFilterComparer.Compare("/finance", "/+");
+                MqttTopicFilterComparer.Compare("/finance", "+");
             }
         }
 

Tests/MQTTnet.Core.Tests/Server/General.cs

@@ -202,248 +202,7 @@ namespace MQTTnet.Tests.Server
                 Assert.AreEqual(1, receivedMessagesCount);
             }
         }
-
-        [TestMethod]
-        public async Task Intercept_Subscription()
-        {
-            using (var testEnvironment = new TestEnvironment(TestContext))
-            {
-                await testEnvironment.StartServer(new MqttServerOptionsBuilder().WithSubscriptionInterceptor(
-                    c =>
-                    {
-                        // Set the topic to "a" regards what the client wants to subscribe.
-                        c.TopicFilter.Topic = "a";
-                    }));
-
-                var topicAReceived = false;
-                var topicBReceived = false;
-
-                var client = await testEnvironment.ConnectClient();
-                client.UseApplicationMessageReceivedHandler(c =>
-                {
-                    if (c.ApplicationMessage.Topic == "a")
-                    {
-                        topicAReceived = true;
-                    }
-                    else if (c.ApplicationMessage.Topic == "b")
-                    {
-                        topicBReceived = true;
-                    }
-                });
-
-                await client.SubscribeAsync("b");
-
-                await client.PublishAsync("a");
-
-                await Task.Delay(500);
-
-                Assert.IsTrue(topicAReceived);
-                Assert.IsFalse(topicBReceived);
-            }
-        }
-
-        [TestMethod]
-        public async Task Subscribe_Unsubscribe()
-        {
-            using (var testEnvironment = new TestEnvironment(TestContext))
-            {
-                var receivedMessagesCount = 0;
-
-                var server = await testEnvironment.StartServer();
-
-                var c1 = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithClientId("c1"));
-                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
-
-                var c2 = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithClientId("c2"));
-
-                var message = new MqttApplicationMessageBuilder().WithTopic("a").WithAtLeastOnceQoS().Build();
-                await c2.PublishAsync(message);
-
-                await Task.Delay(500);
-                Assert.AreEqual(0, receivedMessagesCount);
-
-                var subscribeEventCalled = false;
-                server.ClientSubscribedTopicHandler = new MqttServerClientSubscribedTopicHandlerDelegate(e =>
-                {
-                    subscribeEventCalled = e.TopicFilter.Topic == "a" && e.ClientId == c1.Options.ClientId;
-                });
-
-                await c1.SubscribeAsync(new MqttTopicFilter { Topic = "a", QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce });
-                await Task.Delay(250);
-                Assert.IsTrue(subscribeEventCalled, "Subscribe event not called.");
-
-                await c2.PublishAsync(message);
-                await Task.Delay(250);
-                Assert.AreEqual(1, receivedMessagesCount);
-
-                var unsubscribeEventCalled = false;
-                server.ClientUnsubscribedTopicHandler = new MqttServerClientUnsubscribedTopicHandlerDelegate(e =>
-                {
-                    unsubscribeEventCalled = e.TopicFilter == "a" && e.ClientId == c1.Options.ClientId;
-                });
-
-                await c1.UnsubscribeAsync("a");
-                await Task.Delay(250);
-                Assert.IsTrue(unsubscribeEventCalled, "Unsubscribe event not called.");
-
-                await c2.PublishAsync(message);
-                await Task.Delay(500);
-                Assert.AreEqual(1, receivedMessagesCount);
-
-                await Task.Delay(500);
-
-                Assert.AreEqual(1, receivedMessagesCount);
-            }
-        }
-
-        [TestMethod]
-        public async Task Subscribe_Multiple_In_Single_Request()
-        {
-            using (var testEnvironment = new TestEnvironment(TestContext))
-            {
-                var receivedMessagesCount = 0;
-
-                await testEnvironment.StartServer();
-
-                var c1 = await testEnvironment.ConnectClient();
-                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
-                await c1.SubscribeAsync(new MqttClientSubscribeOptionsBuilder()
-                    .WithTopicFilter("a")
-                    .WithTopicFilter("b")
-                    .WithTopicFilter("c")
-                    .Build());
-
-                var c2 = await testEnvironment.ConnectClient();
-
-                await c2.PublishAsync("a");
-                await Task.Delay(100);
-                Assert.AreEqual(receivedMessagesCount, 1);
-
-                await c2.PublishAsync("b");
-                await Task.Delay(100);
-                Assert.AreEqual(receivedMessagesCount, 2);
-
-                await c2.PublishAsync("c");
-                await Task.Delay(100);
-                Assert.AreEqual(receivedMessagesCount, 3);
-            }
-        }
-
-        [TestMethod]
-        public async Task Subscribe_Lots_In_Single_Request()
-        {
-            using (var testEnvironment = new TestEnvironment(TestContext))
-            {
-                var receivedMessagesCount = 0;
-
-                await testEnvironment.StartServer();
-
-                var c1 = await testEnvironment.ConnectClient();
-                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
-
-                var optionsBuilder = new MqttClientSubscribeOptionsBuilder();
-                for (var i = 0; i < 500; i++)
-                {
-                    optionsBuilder.WithTopicFilter(i.ToString(), MqttQualityOfServiceLevel.AtMostOnce);
-                }
-
-                await c1.SubscribeAsync(optionsBuilder.Build()).ConfigureAwait(false);
-
-                var c2 = await testEnvironment.ConnectClient();
-
-                var messageBuilder = new MqttApplicationMessageBuilder();
-                for (var i = 0; i < 500; i++)
-                {
-                    messageBuilder.WithTopic(i.ToString());
-
-                    await c2.PublishAsync(messageBuilder.Build()).ConfigureAwait(false);
-                }
-
-                SpinWait.SpinUntil(() => receivedMessagesCount == 500, TimeSpan.FromSeconds(20));
-
-                Assert.AreEqual(500, receivedMessagesCount);
-            }
-        }
-
-        [TestMethod]
-        public async Task Subscribe_Lots_In_Multiple_Requests()
-        {
-            using (var testEnvironment = new TestEnvironment(TestContext))
-            {
-                var receivedMessagesCount = 0;
-
-                await testEnvironment.StartServer();
-
-                var c1 = await testEnvironment.ConnectClient();
-                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
-
-                for (var i = 0; i < 500; i++)
-                {
-                    var so = new MqttClientSubscribeOptionsBuilder()
-                        .WithTopicFilter(i.ToString()).Build();
-
-                    await c1.SubscribeAsync(so).ConfigureAwait(false);
-
-                    await Task.Delay(10);
-                }
-
-                var c2 = await testEnvironment.ConnectClient();
-
-                var messageBuilder = new MqttApplicationMessageBuilder();
-                for (var i = 0; i < 500; i++)
-                {
-                    messageBuilder.WithTopic(i.ToString());
-
-                    await c2.PublishAsync(messageBuilder.Build()).ConfigureAwait(false);
-
-                    await Task.Delay(10);
-                }
-
-                SpinWait.SpinUntil(() => receivedMessagesCount == 500, 5000);
-
-                Assert.AreEqual(500, receivedMessagesCount);
-            }
-        }
-
-        [TestMethod]
-        public async Task Subscribe_Multiple_In_Multiple_Request()
-        {
-            using (var testEnvironment = new TestEnvironment(TestContext))
-            {
-                var receivedMessagesCount = 0;
-
-                await testEnvironment.StartServer();
-
-                var c1 = await testEnvironment.ConnectClient();
-                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
-                await c1.SubscribeAsync(new MqttClientSubscribeOptionsBuilder()
-                    .WithTopicFilter("a")
-                    .Build());
-
-                await c1.SubscribeAsync(new MqttClientSubscribeOptionsBuilder()
-                    .WithTopicFilter("b")
-                    .Build());
-
-                await c1.SubscribeAsync(new MqttClientSubscribeOptionsBuilder()
-                    .WithTopicFilter("c")
-                    .Build());
-
-                var c2 = await testEnvironment.ConnectClient();
-
-                await c2.PublishAsync("a");
-                await Task.Delay(100);
-                Assert.AreEqual(receivedMessagesCount, 1);
-
-                await c2.PublishAsync("b");
-                await Task.Delay(100);
-                Assert.AreEqual(receivedMessagesCount, 2);
-
-                await c2.PublishAsync("c");
-                await Task.Delay(100);
-                Assert.AreEqual(receivedMessagesCount, 3);
-            }
-        }
-
+     
         [TestMethod]
         public async Task Publish_From_Server()
         {

Tests/MQTTnet.Core.Tests/Server/Shared_Subscriptions_Tests.cs

@@ -1,6 +1,7 @@
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using MQTTnet.Client;
+using MQTTnet.Client.Subscribing;
 using MQTTnet.Formatter;
 
 namespace MQTTnet.Tests.Server
@@ -23,5 +24,23 @@ namespace MQTTnet.Tests.Server
                 Assert.IsFalse(connectResult.SharedSubscriptionAvailable);
             }
         }
+        
+        [TestMethod]
+        public async Task Subscription_Of_Shared_Subscription_Is_Denied()
+        {
+            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
+            {
+                await testEnvironment.StartServer();
+
+                var client = testEnvironment.CreateClient();
+                await client.ConnectAsync(testEnvironment.Factory.CreateClientOptionsBuilder()
+                    .WithProtocolVersion(MqttProtocolVersion.V500)
+                    .WithTcpServer("127.0.0.1", testEnvironment.ServerPort).Build());
+
+                var subscribeResult = await client.SubscribeAsync("$share/A");
+                
+                Assert.AreEqual(MqttClientSubscribeResultCode.SharedSubscriptionsNotSupported, subscribeResult.Items[0].ResultCode);
+            }
+        }
     }
 }

Tests/MQTTnet.Core.Tests/Server/Subscribe_Tests.cs

@@ -0,0 +1,282 @@
+using System;
+using System.Threading;
+using System.Threading.Tasks;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using MQTTnet.Client;
+using MQTTnet.Client.Options;
+using MQTTnet.Client.Subscribing;
+using MQTTnet.Formatter;
+using MQTTnet.Protocol;
+using MQTTnet.Server;
+
+namespace MQTTnet.Tests.Server
+{
+    [TestClass]
+    public sealed class Subscribe_Tests : BaseTestClass
+    {
+        [TestMethod]
+        public async Task Intercept_Subscription()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                await testEnvironment.StartServer(new MqttServerOptionsBuilder().WithSubscriptionInterceptor(
+                    c =>
+                    {
+                        // Set the topic to "a" regards what the client wants to subscribe.
+                        c.TopicFilter.Topic = "a";
+                    }));
+
+                var topicAReceived = false;
+                var topicBReceived = false;
+
+                var client = await testEnvironment.ConnectClient();
+                client.UseApplicationMessageReceivedHandler(c =>
+                {
+                    if (c.ApplicationMessage.Topic == "a")
+                    {
+                        topicAReceived = true;
+                    }
+                    else if (c.ApplicationMessage.Topic == "b")
+                    {
+                        topicBReceived = true;
+                    }
+                });
+
+                await client.SubscribeAsync("b");
+
+                await client.PublishAsync("a");
+
+                await Task.Delay(500);
+
+                Assert.IsTrue(topicAReceived);
+                Assert.IsFalse(topicBReceived);
+            }
+        }
+
+        [TestMethod]
+        public async Task Subscribe_Unsubscribe()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                var receivedMessagesCount = 0;
+
+                var server = await testEnvironment.StartServer();
+
+                var c1 = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithClientId("c1"));
+                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
+
+                var c2 = await testEnvironment.ConnectClient(new MqttClientOptionsBuilder().WithClientId("c2"));
+
+                var message = new MqttApplicationMessageBuilder().WithTopic("a").WithAtLeastOnceQoS().Build();
+                await c2.PublishAsync(message);
+
+                await Task.Delay(500);
+                Assert.AreEqual(0, receivedMessagesCount);
+
+                var subscribeEventCalled = false;
+                server.ClientSubscribedTopicHandler = new MqttServerClientSubscribedTopicHandlerDelegate(e =>
+                {
+                    subscribeEventCalled = e.TopicFilter.Topic == "a" && e.ClientId == c1.Options.ClientId;
+                });
+
+                await c1.SubscribeAsync(new MqttTopicFilter { Topic = "a", QualityOfServiceLevel = MqttQualityOfServiceLevel.AtLeastOnce });
+                await Task.Delay(250);
+                Assert.IsTrue(subscribeEventCalled, "Subscribe event not called.");
+
+                await c2.PublishAsync(message);
+                await Task.Delay(250);
+                Assert.AreEqual(1, receivedMessagesCount);
+
+                var unsubscribeEventCalled = false;
+                server.ClientUnsubscribedTopicHandler = new MqttServerClientUnsubscribedTopicHandlerDelegate(e =>
+                {
+                    unsubscribeEventCalled = e.TopicFilter == "a" && e.ClientId == c1.Options.ClientId;
+                });
+
+                await c1.UnsubscribeAsync("a");
+                await Task.Delay(250);
+                Assert.IsTrue(unsubscribeEventCalled, "Unsubscribe event not called.");
+
+                await c2.PublishAsync(message);
+                await Task.Delay(500);
+                Assert.AreEqual(1, receivedMessagesCount);
+
+                await Task.Delay(500);
+
+                Assert.AreEqual(1, receivedMessagesCount);
+            }
+        }
+
+        [TestMethod]
+        public async Task Subscribe_Multiple_In_Single_Request()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                var receivedMessagesCount = 0;
+
+                await testEnvironment.StartServer();
+
+                var c1 = await testEnvironment.ConnectClient();
+                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
+                await c1.SubscribeAsync(new MqttClientSubscribeOptionsBuilder()
+                    .WithTopicFilter("a")
+                    .WithTopicFilter("b")
+                    .WithTopicFilter("c")
+                    .Build());
+
+                var c2 = await testEnvironment.ConnectClient();
+
+                await c2.PublishAsync("a");
+                await Task.Delay(100);
+                Assert.AreEqual(receivedMessagesCount, 1);
+
+                await c2.PublishAsync("b");
+                await Task.Delay(100);
+                Assert.AreEqual(receivedMessagesCount, 2);
+
+                await c2.PublishAsync("c");
+                await Task.Delay(100);
+                Assert.AreEqual(receivedMessagesCount, 3);
+            }
+        }
+
+        [TestMethod]
+        public async Task Subscribe_Lots_In_Single_Request()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                var receivedMessagesCount = 0;
+
+                await testEnvironment.StartServer();
+
+                var c1 = await testEnvironment.ConnectClient();
+                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
+
+                var optionsBuilder = new MqttClientSubscribeOptionsBuilder();
+                for (var i = 0; i < 500; i++)
+                {
+                    optionsBuilder.WithTopicFilter(i.ToString());
+                }
+
+                await c1.SubscribeAsync(optionsBuilder.Build()).ConfigureAwait(false);
+
+                var c2 = await testEnvironment.ConnectClient();
+
+                var messageBuilder = new MqttApplicationMessageBuilder();
+                for (var i = 0; i < 500; i++)
+                {
+                    messageBuilder.WithTopic(i.ToString());
+
+                    await c2.PublishAsync(messageBuilder.Build()).ConfigureAwait(false);
+                }
+
+                SpinWait.SpinUntil(() => receivedMessagesCount == 500, TimeSpan.FromSeconds(20));
+
+                Assert.AreEqual(500, receivedMessagesCount);
+            }
+        }
+
+        [TestMethod]
+        public async Task Subscribe_Lots_In_Multiple_Requests()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                var receivedMessagesCount = 0;
+
+                await testEnvironment.StartServer();
+
+                var c1 = await testEnvironment.ConnectClient();
+                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
+
+                for (var i = 0; i < 500; i++)
+                {
+                    var so = new MqttClientSubscribeOptionsBuilder()
+                        .WithTopicFilter(i.ToString()).Build();
+
+                    await c1.SubscribeAsync(so).ConfigureAwait(false);
+
+                    await Task.Delay(10);
+                }
+
+                var c2 = await testEnvironment.ConnectClient();
+
+                var messageBuilder = new MqttApplicationMessageBuilder();
+                for (var i = 0; i < 500; i++)
+                {
+                    messageBuilder.WithTopic(i.ToString());
+
+                    await c2.PublishAsync(messageBuilder.Build()).ConfigureAwait(false);
+
+                    await Task.Delay(10);
+                }
+
+                SpinWait.SpinUntil(() => receivedMessagesCount == 500, 5000);
+
+                Assert.AreEqual(500, receivedMessagesCount);
+            }
+        }
+
+        [TestMethod]
+        public async Task Subscribe_Multiple_In_Multiple_Request()
+        {
+            using (var testEnvironment = CreateTestEnvironment())
+            {
+                var receivedMessagesCount = 0;
+
+                await testEnvironment.StartServer();
+
+                var c1 = await testEnvironment.ConnectClient();
+                c1.UseApplicationMessageReceivedHandler(c => Interlocked.Increment(ref receivedMessagesCount));
+                await c1.SubscribeAsync(new MqttClientSubscribeOptionsBuilder()
+                    .WithTopicFilter("a")
+                    .Build());
+
+                await c1.SubscribeAsync(new MqttClientSubscribeOptionsBuilder()
+                    .WithTopicFilter("b")
+                    .Build());
+
+                await c1.SubscribeAsync(new MqttClientSubscribeOptionsBuilder()
+                    .WithTopicFilter("c")
+                    .Build());
+
+                var c2 = await testEnvironment.ConnectClient();
+
+                await c2.PublishAsync("a");
+                await Task.Delay(100);
+                Assert.AreEqual(receivedMessagesCount, 1);
+
+                await c2.PublishAsync("b");
+                await Task.Delay(100);
+                Assert.AreEqual(receivedMessagesCount, 2);
+
+                await c2.PublishAsync("c");
+                await Task.Delay(100);
+                Assert.AreEqual(receivedMessagesCount, 3);
+            }
+        }
+        
+        [TestMethod]
+        public async Task Deny_Invalid_Topic()
+        {
+            using (var testEnvironment = CreateTestEnvironment(MqttProtocolVersion.V500))
+            {
+                await testEnvironment.StartServer(new MqttServerOptionsBuilder().WithSubscriptionInterceptor(
+                    c =>
+                    {
+                        if (c.TopicFilter.Topic == "not_allowed_topic")
+                        {
+                            c.ReasonCode = MqttSubscribeReasonCode.TopicFilterInvalid;
+                        }
+                    }));
+                
+                var client = await testEnvironment.ConnectClient();
+                
+                var subscribeResult =await client.SubscribeAsync("allowed_topic");
+                Assert.AreEqual(MqttClientSubscribeResultCode.GrantedQoS0, subscribeResult.Items[0].ResultCode);
+
+                subscribeResult =await client.SubscribeAsync("not_allowed_topic");
+                Assert.AreEqual(MqttClientSubscribeResultCode.TopicFilterInvalid, subscribeResult.Items[0].ResultCode);
+            }
+        }
+    }
+}

Tests/MQTTnet.Core.Tests/Server/TopicFilterComparer_Tests.cs

@@ -4,111 +4,135 @@ using MQTTnet.Server.Internal;
 namespace MQTTnet.Tests.Server
 {
     [TestClass]
-    public class TopicFilterComparer_Tests
+    public sealed class MqttTopicFilterComparer_Tests
     {
         [TestMethod]
-        public void TopicFilterComparer_Plus_Match_With_Separator_Only()
+        public void Plus_Match_With_Separator_Only()
         {
             //A Topic Name or Topic Filter consisting only of the ‘/’ character is valid
-            CompareAndAssert("A", "+", true);
+            CompareAndAssert("A", "+", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_Hash_Match_With_Separator_Only()
+        public void Hash_Match_With_Separator_Only()
         {
             //A Topic Name or Topic Filter consisting only of the ‘/’ character is valid
-            CompareAndAssert("/", "#", true);
+            CompareAndAssert("/", "#", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_DirectMatch()
+        public void DirectMatch()
         {
-            CompareAndAssert("A/B/C", "A/B/C", true);
+            CompareAndAssert("A/B/C", "A/B/C", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_DirectNoMatch()
+        public void DirectNoMatch()
         {
-            CompareAndAssert("A/B/X", "A/B/C", false);
+            CompareAndAssert("A/B/X", "A/B/C", MqttTopicFilterCompareResult.NoMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_MiddleOneLevelWildcardMatch()
+        public void MiddleOneLevelWildcardMatch()
         {
-            CompareAndAssert("A/B/C", "A/+/C", true);
+            CompareAndAssert("A/B/C", "A/+/C", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_MiddleOneLevelWildcardNoMatch()
+        public void MiddleOneLevelWildcardNoMatch()
         {
-            CompareAndAssert("A/B/C/D", "A/+/C", false);
+            CompareAndAssert("A/B/C/D", "A/+/C", MqttTopicFilterCompareResult.NoMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_BeginningOneLevelWildcardMatch()
+        public void BeginningOneLevelWildcardMatch()
         {
-            CompareAndAssert("A/B/C", "+/B/C", true);
+            CompareAndAssert("A/B/C", "+/B/C", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_EndOneLevelWildcardMatch()
+        public void EndOneLevelWildcardMatch()
         {
-            CompareAndAssert("A/B/C", "A/B/+", true);
+            CompareAndAssert("A/B/C", "A/B/+", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_EndMultipleLevelsWildcardMatch()
+        public void EndMultipleLevelsWildcardMatch()
         {
-            CompareAndAssert("A/B/C", "A/#", true);
+            CompareAndAssert("A/B/C", "A/#", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_EndMultipleLevelsWildcardNoMatch()
+        public void EndMultipleLevelsWildcardNoMatch()
         {
-            CompareAndAssert("A/B/C/D", "A/C/#", false);
+            CompareAndAssert("A/B/C/D", "A/C/#", MqttTopicFilterCompareResult.NoMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_EndMultipleLevelsWildcardMatchEmptyLevel()
+        public void EndMultipleLevelsWildcardMatchEmptyLevel()
         {
-            CompareAndAssert("A/", "A/#", true);
+            CompareAndAssert("A/", "A/#", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_AllLevelsWildcardMatch()
+        public void AllLevelsWildcardMatch()
         {
-            CompareAndAssert("A/B/C/D", "#", true);
+            CompareAndAssert("A/B/C/D", "#", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_MultiLevel_Sport()
+        public void MultiLevel_Sport()
         {
             // Tests from official MQTT spec (4.7.1.2 Multi-level wildcard)
-            CompareAndAssert("sport/tennis/player1", "sport/tennis/player1/#", true);
-            CompareAndAssert("sport/tennis/player1/ranking", "sport/tennis/player1/#", true);
-            CompareAndAssert("sport/tennis/player1/score/wimbledon", "sport/tennis/player1/#", true);
+            CompareAndAssert("sport/tennis/player1", "sport/tennis/player1/#", MqttTopicFilterCompareResult.IsMatch);
+            CompareAndAssert("sport/tennis/player1/ranking", "sport/tennis/player1/#", MqttTopicFilterCompareResult.IsMatch);
+            CompareAndAssert("sport/tennis/player1/score/wimbledon", "sport/tennis/player1/#", MqttTopicFilterCompareResult.IsMatch);
 
-            CompareAndAssert("sport/tennis/player1", "sport/tennis/+", true);
-            CompareAndAssert("sport/tennis/player2", "sport/tennis/+", true);
-            CompareAndAssert("sport/tennis/player1/ranking", "sport/tennis/+", false);
+            CompareAndAssert("sport/tennis/player1", "sport/tennis/+", MqttTopicFilterCompareResult.IsMatch);
+            CompareAndAssert("sport/tennis/player2", "sport/tennis/+", MqttTopicFilterCompareResult.IsMatch);
+            CompareAndAssert("sport/tennis/player1/ranking", "sport/tennis/+", MqttTopicFilterCompareResult.NoMatch);
 
-            CompareAndAssert("sport", "sport/#", true);
-            CompareAndAssert("sport", "sport/+", false);
-            CompareAndAssert("sport/", "sport/+", true);
+            CompareAndAssert("sport", "sport/#", MqttTopicFilterCompareResult.IsMatch);
+            CompareAndAssert("sport", "sport/+", MqttTopicFilterCompareResult.NoMatch);
+            CompareAndAssert("sport/", "sport/+", MqttTopicFilterCompareResult.IsMatch);
         }
 
         [TestMethod]
-        public void TopicFilterComparer_SingleLevel_Finance()
+        public void SingleLevel_Finance()
         {
             // Tests from official MQTT spec (4.7.1.3 Single level wildcard)
-            CompareAndAssert("/finance", "+/+", true);
-            CompareAndAssert("/finance", "/+", true);
-            CompareAndAssert("/finance", "+", false);
+            CompareAndAssert("/finance", "+/+", MqttTopicFilterCompareResult.IsMatch);
+            CompareAndAssert("/finance", "/+", MqttTopicFilterCompareResult.IsMatch);
+            CompareAndAssert("/finance", "+", MqttTopicFilterCompareResult.NoMatch);
         }
-
-        private static void CompareAndAssert(string topic, string filter, bool expectedResult)
+        
+        [TestMethod]
+        public void Reserved_Multi_Level_Wildcard_Only()
         {
-            Assert.AreEqual(expectedResult, MqttTopicFilterComparer.IsMatch(topic, filter));
+            CompareAndAssert("$SPECIAL/TOPIC", "#", MqttTopicFilterCompareResult.NoMatch);
+        }
+        
+        [TestMethod]
+        public void Reserved_Single_Level_Wildcard_Prefix()
+        {
+            CompareAndAssert("$SYS/monitor/Clients", "+/monitor/Clients", MqttTopicFilterCompareResult.NoMatch);
+        }
+        
+        [TestMethod]
+        public void Reserved_Single_Level_Wildcard_Suffix()
+        {
+            CompareAndAssert("$SYS/monitor/Clients", "$SYS/monitor/+", MqttTopicFilterCompareResult.IsMatch);
+        }
+        
+        [TestMethod]
+        public void Reserved_Single_Level_Wildcard()
+        {
+            CompareAndAssert("$SYS/monitor/Clients", "$SYS/#", MqttTopicFilterCompareResult.IsMatch);
+        }
+        
+        static void CompareAndAssert(string topic, string filter, MqttTopicFilterCompareResult expectedResult)
+        {
+            Assert.AreEqual(expectedResult, MqttTopicFilterComparer.Compare(topic, filter));
         }
     }
 }

Tests/MQTTnet.TestApp.NetCore/ServerTest.cs

@@ -55,7 +55,7 @@ namespace MQTTnet.TestApp.NetCore
 
                     ApplicationMessageInterceptor = new MqttServerApplicationMessageInterceptorDelegate(context =>
                     {
-                        if (MqttTopicFilterComparer.IsMatch(context.ApplicationMessage.Topic, "/myTopic/WithTimestamp/#"))
+                        if (MqttTopicFilterComparer.Compare(context.ApplicationMessage.Topic, "/myTopic/WithTimestamp/#") == MqttTopicFilterCompareResult.IsMatch)
                         {
                             // Replace the payload with the timestamp. But also extending a JSON 
                             // based payload with the timestamp is a suitable use case.