Throw exception when we try to reference a type that cannot be referenced on OpenApiParameter

Author: simon-pearson-lmk

src/Microsoft.OpenApi/Extensions/OpenApiReferencableExtensions.cs

@@ -4,8 +4,10 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using Microsoft.OpenApi.Exceptions;
 using Microsoft.OpenApi.Interfaces;
 using Microsoft.OpenApi.Models;
+using Microsoft.OpenApi.Properties;
 using Microsoft.OpenApi.Services;
 using Microsoft.OpenApi.Validations;
 
@@ -26,27 +28,37 @@ public static IOpenApiReferenceable ResolveReference(this IOpenApiReferenceable
         {
             if (jsonPointer == string.Empty)
                 return element;
-            if (element.GetType() == typeof(OpenApiParameter))
+            try
             {
-                return ResolveReferenceOnParameterElement((OpenApiParameter)element, jsonPointer);
+                if (element.GetType() == typeof(OpenApiParameter))
+                {
+                    return ResolveReferenceOnParameterElement((OpenApiParameter)element, jsonPointer);
+                }
+            }
+            catch (KeyNotFoundException)
+            {
+                throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
             }
             throw new NotImplementedException();
         }
 
         private static IOpenApiReferenceable ResolveReferenceOnParameterElement(OpenApiParameter parameterElement, string jsonPointer)
         {
             var jsonPointerTokens = jsonPointer.Split('/');
-            switch (jsonPointerTokens.First())
+            var propertyName = jsonPointerTokens.First();
+            switch (propertyName)
             {
                 case OpenApiConstants.Schema:
                     return parameterElement.Schema;
                 case OpenApiConstants.Examples:
                     {
-                        var mapKey = jsonPointerTokens.ElementAt(1);
+                        var mapKey = jsonPointerTokens.ElementAtOrDefault(1);
+                        if (!(jsonPointerTokens.Length >= 2 && parameterElement.Examples.ContainsKey(mapKey)))
+                            throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
                         return parameterElement.Examples[mapKey];
                     }
                 default:
-                    throw new NotImplementedException();
+                    throw new OpenApiException(string.Format(SRResource.InvalidReferenceId, jsonPointer));
             }
         }
     }

test/Microsoft.OpenApi.Tests/Workspaces/OpenApiReferencableTests.cs

@@ -1,10 +1,13 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
+using System;
 using System.Collections.Generic;
+using Microsoft.OpenApi.Exceptions;
 using Microsoft.OpenApi.Extensions;
 using Microsoft.OpenApi.Interfaces;
 using Microsoft.OpenApi.Models;
+using Microsoft.OpenApi.Properties;
 using Xunit;
 
 namespace Microsoft.OpenApi.Tests.Workspaces
@@ -75,5 +78,36 @@ public void ParameterElementCanResolveReferenceToExampleTmpDbgImproveMyName()
             // Assert
             Assert.Same(parameterElement.Examples["example1"], resolvedReference);
         }
+
+        public static IEnumerable<object[]> ParameterElementShouldThrowOnInvalidReferenceIdTestData =>
+        new List<object[]>
+        {
+            new object[] { "/" },
+            new object[] { "a" },
+            new object[] { "examples" },
+            new object[] { "examples/a" },
+
+        };
+
+        [Theory]
+        [MemberData(nameof(ParameterElementShouldThrowOnInvalidReferenceIdTestData))]
+        public void ParameterElementShouldThrowOnInvalidReferenceId(string jsonPointer)
+        {
+            // Arrange
+            var parameterElement = new OpenApiParameter
+            {
+                Examples = new Dictionary<string, OpenApiExample>()
+            {
+                { "example1", new OpenApiExample() }
+            },
+            };
+
+            // Act
+            Action resolveReference = () => parameterElement.ResolveReference(jsonPointer);
+
+            // Assert
+            var exception = Assert.Throws<OpenApiException>(resolveReference);
+            Assert.Equal(String.Format(SRResource.InvalidReferenceId, jsonPointer), exception.Message);
+        }
     }
 }