fix: path item reference implementation

src/Microsoft.OpenApi.Hidi/Formatters/PowerShellFormatter.cs

@@ -51,7 +51,7 @@ public override void Visit(OpenApiSchema schema)
             base.Visit(schema);
         }
 
-        public override void Visit(OpenApiPathItem pathItem)
+        public override void Visit(IOpenApiPathItem pathItem)
         {
             if (pathItem.Operations.TryGetValue(OperationType.Put, out var value) &&
                 value.OperationId != null)
@@ -81,13 +81,13 @@ public override void Visit(OpenApiOperation operation)
             operationId = ResolveODataCastOperationId(operationId);
             operationId = ResolveByRefOperationId(operationId);
             // Verb segment resolution should always be last. user.get -> user_Get
-            operationId = ResolveVerbSegmentInOpertationId(operationId);
+            operationId = ResolveVerbSegmentInOperationId(operationId);
 
             operation.OperationId = operationId;
             base.Visit(operation);
         }
 
-        private static string ResolveVerbSegmentInOpertationId(string operationId)
+        private static string ResolveVerbSegmentInOperationId(string operationId)
         {
             var charPos = operationId.LastIndexOf('.', operationId.Length - 1);
             if (operationId.Contains('_', StringComparison.OrdinalIgnoreCase) || charPos < 0)

src/Microsoft.OpenApi.Hidi/StatsVisitor.cs

@@ -34,7 +34,7 @@ public override void Visit(IDictionary<string, IOpenApiHeader> headers)
 
         public int PathItemCount { get; set; }
 
-        public override void Visit(OpenApiPathItem pathItem)
+        public override void Visit(IOpenApiPathItem pathItem)
         {
             PathItemCount++;
         }

src/Microsoft.OpenApi.Workbench/StatsVisitor.cs

@@ -34,7 +34,7 @@ public override void Visit(IDictionary<string, IOpenApiHeader> headers)
 
         public int PathItemCount { get; set; }
 
-        public override void Visit(OpenApiPathItem pathItem)
+        public override void Visit(IOpenApiPathItem pathItem)
         {
             PathItemCount++;
         }

src/Microsoft.OpenApi/Models/Interfaces/IOpenApiCallback.cs

@@ -14,5 +14,5 @@ public interface IOpenApiCallback : IOpenApiSerializable, IOpenApiReadOnlyExtens
     /// <summary>
     /// A Path Item Object used to define a callback request and expected responses.
     /// </summary>
-    public Dictionary<RuntimeExpression, OpenApiPathItem> PathItems { get; }
+    public Dictionary<RuntimeExpression, IOpenApiPathItem> PathItems { get; }
 }

src/Microsoft.OpenApi/Models/Interfaces/IOpenApiPathItem.cs

@@ -0,0 +1,28 @@
+
+using System.Collections.Generic;
+using Microsoft.OpenApi.Interfaces;
+
+namespace Microsoft.OpenApi.Models.Interfaces;
+
+/// <summary>
+/// Defines the base properties for the path item object.
+/// This interface is provided for type assertions but should not be implemented by package consumers beyond automatic mocking.
+/// </summary>
+public interface IOpenApiPathItem : IOpenApiDescribedElement, IOpenApiSummarizedElement, IOpenApiSerializable, IOpenApiReadOnlyExtensible
+{
+    /// <summary>
+    /// Gets the definition of operations on this path.
+    /// </summary>
+    public IDictionary<OperationType, OpenApiOperation> Operations { get; }
+
+    /// <summary>
+    /// An alternative server array to service all operations in this path.
+    /// </summary>
+    public IList<OpenApiServer> Servers { get; }
+
+    /// <summary>
+    /// A list of parameters that are applicable for all the operations described under this path.
+    /// These parameters can be overridden at the operation level, but cannot be removed there.
+    /// </summary>
+    public IList<IOpenApiParameter> Parameters { get; }
+}

src/Microsoft.OpenApi/Models/OpenApiCallback.cs

@@ -16,7 +16,7 @@ namespace Microsoft.OpenApi.Models
     public class OpenApiCallback : IOpenApiReferenceable, IOpenApiExtensible, IOpenApiCallback
     {
         /// <inheritdoc/>
-        public Dictionary<RuntimeExpression, OpenApiPathItem> PathItems { get; set; }
+        public Dictionary<RuntimeExpression, IOpenApiPathItem> PathItems { get; set; }
             = [];
 
 
@@ -40,11 +40,11 @@ public OpenApiCallback(IOpenApiCallback callback)
         }
 
         /// <summary>
-        /// Add a <see cref="OpenApiPathItem"/> into the <see cref="PathItems"/>.
+        /// Add a <see cref="IOpenApiPathItem"/> into the <see cref="PathItems"/>.
         /// </summary>
         /// <param name="expression">The runtime expression.</param>
         /// <param name="pathItem">The path item.</param>
-        public void AddPathItem(RuntimeExpression expression, OpenApiPathItem pathItem)
+        public void AddPathItem(RuntimeExpression expression, IOpenApiPathItem pathItem)
         {
             Utils.CheckArgumentNull(expression);
             Utils.CheckArgumentNull(pathItem);

src/Microsoft.OpenApi/Models/OpenApiComponents.cs

@@ -66,9 +66,9 @@ public class OpenApiComponents : IOpenApiSerializable, IOpenApiExtensible
         public IDictionary<string, IOpenApiCallback>? Callbacks { get; set; } = new Dictionary<string, IOpenApiCallback>();
 
         /// <summary>
-        /// An object to hold reusable <see cref="OpenApiPathItem"/> Object.
+        /// An object to hold reusable <see cref="IOpenApiPathItem"/> Object.
         /// </summary>
-        public IDictionary<string, OpenApiPathItem>? PathItems { get; set; } = new Dictionary<string, OpenApiPathItem>();
+        public IDictionary<string, IOpenApiPathItem>? PathItems { get; set; } = new Dictionary<string, IOpenApiPathItem>();
 
         /// <summary>
         /// This object MAY be extended with Specification Extensions.
@@ -94,7 +94,7 @@ public OpenApiComponents(OpenApiComponents? components)
             SecuritySchemes = components?.SecuritySchemes != null ? new Dictionary<string, OpenApiSecurityScheme>(components.SecuritySchemes) : null;
             Links = components?.Links != null ? new Dictionary<string, IOpenApiLink>(components.Links) : null;
             Callbacks = components?.Callbacks != null ? new Dictionary<string, IOpenApiCallback>(components.Callbacks) : null;
-            PathItems = components?.PathItems != null ? new Dictionary<string, OpenApiPathItem>(components.PathItems) : null;
+            PathItems = components?.PathItems != null ? new Dictionary<string, IOpenApiPathItem>(components.PathItems) : null;
             Extensions = components?.Extensions != null ? new Dictionary<string, IOpenApiExtension>(components.Extensions) : null;
         }
 

src/Microsoft.OpenApi/Models/OpenApiDocument.cs

@@ -56,7 +56,7 @@ public class OpenApiDocument : IOpenApiSerializable, IOpenApiExtensible, IOpenAp
         /// A map of requests initiated other than by an API call, for example by an out of band registration. 
         /// The key name is a unique string to refer to each webhook, while the (optionally referenced) Path Item Object describes a request that may be initiated by the API provider and the expected responses
         /// </summary>
-        public IDictionary<string, OpenApiPathItem>? Webhooks { get; set; } = new Dictionary<string, OpenApiPathItem>();
+        public IDictionary<string, IOpenApiPathItem>? Webhooks { get; set; } = new Dictionary<string, IOpenApiPathItem>();
 
         /// <summary>
         /// An element to hold various schemas for the specification.
@@ -113,7 +113,7 @@ public OpenApiDocument(OpenApiDocument? document)
             JsonSchemaDialect = document?.JsonSchemaDialect ?? JsonSchemaDialect;
             Servers = document?.Servers != null ? new List<OpenApiServer>(document.Servers) : null;
             Paths = document?.Paths != null ? new(document?.Paths) : new OpenApiPaths();
-            Webhooks = document?.Webhooks != null ? new Dictionary<string, OpenApiPathItem>(document.Webhooks) : null;
+            Webhooks = document?.Webhooks != null ? new Dictionary<string, IOpenApiPathItem>(document.Webhooks) : null;
             Components = document?.Components != null ? new(document?.Components) : null;
             SecurityRequirements = document?.SecurityRequirements != null ? new List<OpenApiSecurityRequirement>(document.SecurityRequirements) : null;
             Tags = document?.Tags != null ? new List<OpenApiTag>(document.Tags) : null;
@@ -612,7 +612,7 @@ public bool AddComponent<T>(string id, T componentToRegister)
                     Components.Callbacks.Add(id, openApiCallback);
                     break;
                 case OpenApiPathItem openApiPathItem:
-                    Components.PathItems ??= new Dictionary<string, OpenApiPathItem>();
+                    Components.PathItems ??= new Dictionary<string, IOpenApiPathItem>();
                     Components.PathItems.Add(id, openApiPathItem);
                     break;
                 case OpenApiExample openApiExample:

src/Microsoft.OpenApi/Models/OpenApiPathItem.cs

@@ -13,49 +13,26 @@ namespace Microsoft.OpenApi.Models
     /// <summary>
     /// Path Item Object: to describe the operations available on a single path.
     /// </summary>
-    public class OpenApiPathItem : IOpenApiExtensible, IOpenApiReferenceable
+    public class OpenApiPathItem : IOpenApiExtensible, IOpenApiReferenceable, IOpenApiPathItem
     {
-        /// <summary>
-        /// An optional, string summary, intended to apply to all operations in this path.
-        /// </summary>
-        public virtual string Summary { get; set; }
+        /// <inheritdoc/>
+        public string Summary { get; set; }
 
-        /// <summary>
-        /// An optional, string description, intended to apply to all operations in this path.
-        /// </summary>
-        public virtual string Description { get; set; }
+        /// <inheritdoc/>
+        public string Description { get; set; }
 
-        /// <summary>
-        /// Gets the definition of operations on this path.
-        /// </summary>
-        public virtual IDictionary<OperationType, OpenApiOperation> Operations { get; set; }
+        /// <inheritdoc/>
+        public IDictionary<OperationType, OpenApiOperation> Operations { get; set; }
             = new Dictionary<OperationType, OpenApiOperation>();
 
-        /// <summary>
-        /// An alternative server array to service all operations in this path.
-        /// </summary>
-        public virtual IList<OpenApiServer> Servers { get; set; } = new List<OpenApiServer>();
-
-        /// <summary>
-        /// A list of parameters that are applicable for all the operations described under this path.
-        /// These parameters can be overridden at the operation level, but cannot be removed there.
-        /// </summary>
-        public virtual IList<IOpenApiParameter> Parameters { get; set; } = new List<IOpenApiParameter>();
+        /// <inheritdoc/>
+        public IList<OpenApiServer> Servers { get; set; } = [];
 
-        /// <summary>
-        /// This object MAY be extended with Specification Extensions.
-        /// </summary>
-        public virtual IDictionary<string, IOpenApiExtension> Extensions { get; set; } = new Dictionary<string, IOpenApiExtension>();
+        /// <inheritdoc/>
+        public IList<IOpenApiParameter> Parameters { get; set; } = [];
 
-        /// <summary>
-        /// Indicates if object is populated with data or is just a reference to the data
-        /// </summary>
-        public bool UnresolvedReference { get; set; }
-
-        /// <summary>
-        /// Reference object.
-        /// </summary>
-        public OpenApiReference Reference { get; set; }
+        /// <inheritdoc/>
+        public IDictionary<string, IOpenApiExtension> Extensions { get; set; } = new Dictionary<string, IOpenApiExtension>();
 
         /// <summary>
         /// Add one operation into this path item.
@@ -75,30 +52,29 @@ public OpenApiPathItem() { }
         /// <summary>
         /// Initializes a clone of an <see cref="OpenApiPathItem"/> object
         /// </summary>
-        public OpenApiPathItem(OpenApiPathItem pathItem)
+        public OpenApiPathItem(IOpenApiPathItem pathItem)
         {
+            Utils.CheckArgumentNull(pathItem);
             Summary = pathItem?.Summary ?? Summary;
             Description = pathItem?.Description ?? Description;
             Operations = pathItem?.Operations != null ? new Dictionary<OperationType, OpenApiOperation>(pathItem.Operations) : null;
             Servers = pathItem?.Servers != null ? new List<OpenApiServer>(pathItem.Servers) : null;
             Parameters = pathItem?.Parameters != null ? new List<IOpenApiParameter>(pathItem.Parameters) : null;
             Extensions = pathItem?.Extensions != null ? new Dictionary<string, IOpenApiExtension>(pathItem.Extensions) : null;
-            UnresolvedReference = pathItem?.UnresolvedReference ?? UnresolvedReference;
-            Reference = pathItem?.Reference != null ? new(pathItem?.Reference) : null;
         }
 
         /// <summary>
         /// Serialize <see cref="OpenApiPathItem"/> to Open Api v3.1
         /// </summary>
-        public virtual void SerializeAsV31(IOpenApiWriter writer)
+        public void SerializeAsV31(IOpenApiWriter writer)
         {
             SerializeInternal(writer, OpenApiSpecVersion.OpenApi3_1, (writer, element) => element.SerializeAsV31(writer));
         }
 
         /// <summary>
         /// Serialize <see cref="OpenApiPathItem"/> to Open Api v3.0
         /// </summary>
-        public virtual void SerializeAsV3(IOpenApiWriter writer)
+        public void SerializeAsV3(IOpenApiWriter writer)
         {
             SerializeInternal(writer, OpenApiSpecVersion.OpenApi3_0, (writer, element) => element.SerializeAsV3(writer));
         }

src/Microsoft.OpenApi/Models/OpenApiPaths.cs

@@ -1,12 +1,14 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license.
 
+using Microsoft.OpenApi.Models.Interfaces;
+
 namespace Microsoft.OpenApi.Models
 {
     /// <summary>
     /// Paths object.
     /// </summary>
-    public class OpenApiPaths : OpenApiExtensibleDictionary<OpenApiPathItem>
+    public class OpenApiPaths : OpenApiExtensibleDictionary<IOpenApiPathItem>
     {
         /// <summary>
         /// Parameterless constructor

src/Microsoft.OpenApi/Models/References/OpenApiCallbackReference.cs

@@ -42,7 +42,7 @@ internal OpenApiCallbackReference(OpenApiCallback target, string referenceId):ba
         }
 
         /// <inheritdoc/>
-        public Dictionary<RuntimeExpression, OpenApiPathItem> PathItems { get => Target?.PathItems; }
+        public Dictionary<RuntimeExpression, IOpenApiPathItem> PathItems { get => Target?.PathItems; }
 
         /// <inheritdoc/>
         public IDictionary<string, IOpenApiExtension> Extensions { get => Target?.Extensions; }