Resolve reference to 'schema' property on Parameter element

Author: simon-pearson-lmk

src/Microsoft.OpenApi/Extensions/OpenApiReferencableExtensions.cs

@@ -3,6 +3,7 @@
 
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using Microsoft.OpenApi.Interfaces;
 using Microsoft.OpenApi.Models;
 using Microsoft.OpenApi.Services;
@@ -23,7 +24,30 @@ public static class OpenApiReferencableExtensions
         /// <returns>An IEnumerable of errors.  This function will never return null.</returns>
         public static IOpenApiReferenceable ResolveReference(this IOpenApiReferenceable element, string jsonPointer)
         {
-            return element;
+            if (jsonPointer == string.Empty)
+                return element;
+            if (element.GetType() == typeof(OpenApiParameter))
+            {
+                return ResolveReferenceOnParameterElement((OpenApiParameter)element, jsonPointer);
+            }
+            throw new NotImplementedException();
+        }
+
+        private static IOpenApiReferenceable ResolveReferenceOnParameterElement(OpenApiParameter parameterElement, string jsonPointer)
+        {
+            var jsonPointerTokens = jsonPointer.Split('/');
+            switch (jsonPointerTokens.First())
+            {
+                case OpenApiConstants.Schema:
+                    return parameterElement.Schema;
+                case OpenApiConstants.Examples:
+                    {
+                        var mapKey = jsonPointerTokens.ElementAt(1);
+                        return parameterElement.Examples[mapKey];
+                    }
+                default:
+                    throw new NotImplementedException();
+            }
         }
     }
 }

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

@@ -40,5 +40,40 @@ public void ReferencableElementResolvesEmptyJsonPointerToItself(IOpenApiReferenc
             // Assert
             Assert.Same(referencableElement, resolvedReference);
         }
+
+        [Fact]
+        public void ParameterElementCanResolveReferenceToSchemaProperty()
+        {
+            // Arrange
+            var parameterElement = new OpenApiParameter
+            {
+                Schema = new OpenApiSchema()
+            };
+
+            // Act
+            var resolvedReference = parameterElement.ResolveReference("schema");
+
+            // Assert
+            Assert.Same(parameterElement.Schema, resolvedReference);
+        }
+
+        [Fact]
+        public void ParameterElementCanResolveReferenceToExampleTmpDbgImproveMyName()
+        {
+            // Arrange
+            var parameterElement = new OpenApiParameter
+            {
+                Examples = new Dictionary<string, OpenApiExample>()
+            {
+                { "example1", new OpenApiExample() }
+            },
+            };
+
+            // Act
+            var resolvedReference = parameterElement.ResolveReference("examples/example1");
+
+            // Assert
+            Assert.Same(parameterElement.Examples["example1"], resolvedReference);
+        }
     }
 }