add uniqueness check as well

Author: VisualBean

src/LEGO.AsyncAPI/Resource.Designer.cs

@@ -117,6 +117,9 @@
   <resheader name="writer">
     <value>System.Resources.ResXResourceWriter, System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089</value>
   </resheader>
+  <data name="Validation_ChannelsMustBeUnique" xml:space="preserve">
+    <value>Channel signature '{0}' MUST be unique.</value>
+  </data>
   <data name="Validation_EmailMustBeEmailFormat" xml:space="preserve">
     <value>The string '{0}' MUST be an email address.</value>
   </data>

src/LEGO.AsyncAPI/Resource.resx

@@ -3,6 +3,7 @@
 namespace LEGO.AsyncAPI.Validation.Rules
 {
     using System;
+    using System.Collections.Generic;
     using System.Linq;
     using System.Text.RegularExpressions;
     using LEGO.AsyncAPI.Models;
@@ -12,6 +13,7 @@ namespace LEGO.AsyncAPI.Validation.Rules
     public static class AsyncApiDocumentRules
     {
         private static TimeSpan RegexTimeout = TimeSpan.FromSeconds(1);
+
         /// <summary>
         /// The key regex.
         /// </summary>
@@ -35,22 +37,31 @@ public static class AsyncApiDocumentRules
                     context.Enter("channels");
                     try
                     {
+                        // MUST have at least 1 channel
                         if (document.Channels == null || !document.Channels.Keys.Any())
                         {
                             context.CreateError(
                                 nameof(DocumentRequiredFields),
                                 string.Format(Resource.Validation_FieldRequired, "channels", "document"));
                             return;
                         }
-
+                        var hashSet = new HashSet<string>();
                         foreach (var key in document.Channels.Keys)
                         {
+                            // Uri-template
                             if (!ChannelKeyUriTemplateRegex.IsMatch(key))
                             {
                                 context.CreateError(
                                     "ChannelKeys",
                                     string.Format(Resource.Validation_KeyMustMatchRegularExpr, key, "channels", KeyRegex.ToString()));
                             }
+
+                            // Unique channel keys
+                            var pathSignature = GetKeySignature(key);
+                            if (!hashSet.Add(pathSignature))
+                            {
+                                context.CreateError("ChannelKey", string.Format(Resource.Validation_ChannelsMustBeUnique, pathSignature));
+                            }
                         }
                     }
                     finally
@@ -59,6 +70,23 @@ public static class AsyncApiDocumentRules
                     }                    
                 });
 
+        private static string GetKeySignature(string path)
+        {
+            for (int openBrace = path.IndexOf('{'); openBrace > -1; openBrace = path.IndexOf('{', openBrace + 2))
+            {
+                int closeBrace = path.IndexOf('}', openBrace);
+
+                if (closeBrace < 0)
+                {
+                    return path;
+                }
+
+                path = path.Substring(0, openBrace + 1) + path.Substring(closeBrace);
+            }
+
+            return path;
+        }
+
         public static ValidationRule<AsyncApiDocument> KeyMustBeRegularExpression =>
             new ValidationRule<AsyncApiDocument>(
                 (context, document) =>

src/LEGO.AsyncAPI/Validation/Rules/AsyncApiDocumentRules.cs

@@ -46,6 +46,42 @@ public void ChannelKey_WithInvalidParameter_DiagnosticsError(string channelKey)
             diagnostic.Errors.First().Pointer.Should().Be("#/channels");
         }
 
+        [Test]
+        public void ChannelKey_WithNonUniqueKey_DiagnosticsError()
+        {
+            var input =
+                """
+                asyncapi: 2.6.0
+                info:
+                  title: Chat Application
+                  version: 1.0.0
+                servers:
+                  testing:
+                    url: test.mosquitto.org:1883
+                    protocol: mqtt
+                    description: Test broker
+                channels:
+                  chat/{personId}:
+                    publish:
+                      operationId: onMessageReceieved
+                      message:
+                        name: text
+                        payload:
+                          type: string
+                  chat/{personIdentity}:
+                    publish:
+                      operationId: onMessageReceieved
+                      message:
+                        name: text
+                        payload:
+                          type: string
+                """;
+
+            var document = new AsyncApiStringReader().Read(input, out var diagnostic);
+            diagnostic.Errors.First().Message.Should().Be("Channel signature 'chat/{}' MUST be unique.");
+            diagnostic.Errors.First().Pointer.Should().Be("#/channels");
+        }
+
         [Test]
         [TestCase("chat")]
         [TestCase("/some/chat/{personId}")]