fix: resolving wrong reference (#180)

Author: VisualBean

src/LEGO.AsyncAPI/Services/AsyncApiReferenceResolver.cs

@@ -218,7 +218,13 @@ private T ResolveReference<T>(AsyncApiReference reference)
 
             try
             {
-                return this.currentDocument.ResolveReference(reference) as T;
+                var resolvedReference = this.currentDocument.ResolveReference(reference) as T;
+                if (resolvedReference == null)
+                {
+                    throw new AsyncApiException($"Cannot resolve reference '{reference.Reference}' to '{typeof(T).Name}'.");
+                }
+
+                return resolvedReference;
             }
             catch (AsyncApiException ex)
             {

test/LEGO.AsyncAPI.Tests/AsyncApiReaderTests.cs

@@ -6,6 +6,7 @@ namespace LEGO.AsyncAPI.Tests
     using System.Collections.Generic;
     using System.Linq;
     using System.Text.Json.Nodes;
+    using FluentAssertions;
     using LEGO.AsyncAPI.Exceptions;
     using LEGO.AsyncAPI.Models;
     using LEGO.AsyncAPI.Models.Interfaces;
@@ -336,6 +337,32 @@ public void Read_WithBasicPlusSecuritySchemeDeserializes()
             Assert.AreEqual("Provide your username and password for SASL/SCRAM authentication", scheme.Value.Description);
         }
 
+        [Test]
+        public void Read_WithWrongReference_AddsError()
+        {
+            var yaml = 
+                """
+                asyncapi: 2.3.0
+                info:
+                  title: test
+                  version: 1.0.0
+                channels:
+                  workspace:
+                    publish:
+                      message:
+                        $ref: '#/components/securitySchemes/saslScram'
+                components:
+                  securitySchemes:
+                    saslScram:
+                      type: scramSha256
+                      description: Provide your username and password for SASL/SCRAM authentication
+                """;
+            var reader = new AsyncApiStringReader();
+            var doc = reader.Read(yaml, out var diagnostic);
+            diagnostic.Errors.Should().NotBeEmpty();
+            doc.Channels.Values.First().Publish.Message.First().Should().BeNull();
+        }
+
         [Test]
         public void Read_WithBasicPlusOAuthFlowDeserializes()
         {