Validation using walker and single visitor class

Author: darrelmiller

src/Microsoft.OpenApi/Services/OpenApiValidator.cs

@@ -2,8 +2,10 @@
 // Licensed under the MIT license. 
 
 using System.Collections.Generic;
+using System.Linq;
 using Microsoft.OpenApi.Exceptions;
 using Microsoft.OpenApi.Models;
+using Microsoft.OpenApi.Validations;
 
 namespace Microsoft.OpenApi.Services
 {
@@ -12,20 +14,34 @@ namespace Microsoft.OpenApi.Services
     /// </summary>
     public class OpenApiValidator : OpenApiVisitorBase
     {
-        /// <summary>
-        /// Exceptions related to this validation.
-        /// </summary>
-        public List<OpenApiException> Exceptions { get; } = new List<OpenApiException>();
+        readonly ValidationRuleSet _ruleSet;
+        readonly ValidationContext _context;
 
         /// <summary>
-        /// Visit Open API Response element.
+        /// Create a vistor that will validate an OpenAPIDocument
         /// </summary>
-        /// <param name="response">Response element.</param>
-        public override void Visit(OpenApiResponse response)
+        /// <param name="ruleSet"></param>
+        public OpenApiValidator(ValidationRuleSet ruleSet = null)
+        {
+            _ruleSet = ruleSet ?? ValidationRuleSet.DefaultRuleSet;
+            _context = new ValidationContext(_ruleSet);
+        }
+
+        public override void Visit(OpenApiDocument item) => Validate(item);
+        public override void Visit(OpenApiInfo item) => Validate(item);
+        public override void Visit(OpenApiContact item) => Validate(item);
+        public override void Visit(OpenApiResponse item) => Validate(item);
+
+
+        public IEnumerable<ValidationError> Errors => _context.Errors;
+
+        private void Validate<T>(T item)
         {
-            if (string.IsNullOrEmpty(response.Description))
+            if (item == null) return;  // Required fields should be checked by higher level objects
+            var rules = _ruleSet.Where(r => r.ElementType == typeof(T));
+            foreach (var rule in rules)
             {
-                Exceptions.Add(new OpenApiException("Response must have a description"));
+                rule.Evaluate(_context, item);
             }
         }
     }

src/Microsoft.OpenApi/Services/OpenApiVisitorBase.cs

@@ -13,140 +13,147 @@ namespace Microsoft.OpenApi.Services
     public abstract class OpenApiVisitorBase
     {
         /// <summary>
-        /// Validates <see cref="OpenApiDocument"/>
+        /// Visits <see cref="OpenApiDocument"/>
         /// </summary>
         public virtual void Visit(OpenApiDocument doc)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiInfo"/>
+        /// Visits <see cref="OpenApiInfo"/>
         /// </summary>
         public virtual void Visit(OpenApiInfo info)
         {
         }
 
         /// <summary>
-        /// Validates list of <see cref="OpenApiServer"/>
+        /// Visits <see cref="OpenApiContact"/>
+        /// </summary>
+        public virtual void Visit(OpenApiContact contact)
+        {
+        }
+
+        /// <summary>
+        /// Visits list of <see cref="OpenApiServer"/>
         /// </summary>
         public virtual void Visit(IList<OpenApiServer> servers)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiServer"/>
+        /// Visits <see cref="OpenApiServer"/>
         /// </summary>
         public virtual void Visit(OpenApiServer server)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiPaths"/>
+        /// Visits <see cref="OpenApiPaths"/>
         /// </summary>
         public virtual void Visit(OpenApiPaths paths)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiPathItem"/>
+        /// Visits <see cref="OpenApiPathItem"/>
         /// </summary>
         public virtual void Visit(OpenApiPathItem pathItem)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiServerVariable"/>
+        /// Visits <see cref="OpenApiServerVariable"/>
         /// </summary>
         public virtual void Visit(OpenApiServerVariable serverVariable)
         {
         }
 
         /// <summary>
-        /// Validates the operations.
+        /// Visits the operations.
         /// </summary>
         public virtual void Visit(IDictionary<OperationType, OpenApiOperation> operations)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiOperation"/>
+        /// Visits <see cref="OpenApiOperation"/>
         /// </summary>
         public virtual void Visit(OpenApiOperation operation)
         {
         }
 
         /// <summary>
-        /// Validates list of <see cref="OpenApiParameter"/>
+        /// Visits list of <see cref="OpenApiParameter"/>
         /// </summary>
         public virtual void Visit(IList<OpenApiParameter> parameters)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiParameter"/>
+        /// Visits <see cref="OpenApiParameter"/>
         /// </summary>
         public virtual void Visit(OpenApiParameter parameter)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiRequestBody"/>
+        /// Visits <see cref="OpenApiRequestBody"/>
         /// </summary>
         public virtual void Visit(OpenApiRequestBody requestBody)
         {
         }
 
         /// <summary>
-        /// Validates responses.
+        /// Visits responses.
         /// </summary>
         public virtual void Visit(IDictionary<string, OpenApiResponse> responses)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiResponse"/>
+        /// Visits <see cref="OpenApiResponse"/>
         /// </summary>
         public virtual void Visit(OpenApiResponse response)
         {
         }
 
         /// <summary>
-        /// Validates media type content.
+        /// Visits media type content.
         /// </summary>
         public virtual void Visit(IDictionary<string, OpenApiMediaType> content)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiMediaType"/>
+        /// Visits <see cref="OpenApiMediaType"/>
         /// </summary>
         public virtual void Visit(OpenApiMediaType mediaType)
         {
         }
 
         /// <summary>
-        /// Validates the examples.
+        /// Visits the examples.
         /// </summary>
         public virtual void Visit(IDictionary<string, OpenApiExample> examples)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiSchema"/>
+        /// Visits <see cref="OpenApiSchema"/>
         /// </summary>
         public virtual void Visit(OpenApiSchema schema)
         {
         }
 
         /// <summary>
-        /// Validates the links.
+        /// Visits the links.
         /// </summary>
         public virtual void Visit(IDictionary<string, OpenApiLink> links)
         {
         }
 
         /// <summary>
-        /// Validates <see cref="OpenApiLink"/>
+        /// Visits <see cref="OpenApiLink"/>
         /// </summary>
         public virtual void Visit(OpenApiLink link)
         {

test/Microsoft.OpenApi.Tests/Services/OpenApiValidatorTests.cs

@@ -1,11 +1,14 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license. 
 
+using System;
 using System.Collections.Generic;
 using FluentAssertions;
 using Microsoft.OpenApi.Exceptions;
 using Microsoft.OpenApi.Models;
+using Microsoft.OpenApi.Properties;
 using Microsoft.OpenApi.Services;
+using Microsoft.OpenApi.Validations;
 using Xunit;
 
 namespace Microsoft.OpenApi.Tests.Services
@@ -17,7 +20,11 @@ public class OpenApiValidatorTests
         public void ResponseMustHaveADescription()
         {
             var openApiDocument = new OpenApiDocument();
-
+            openApiDocument.Info = new OpenApiInfo()
+            {
+                Title = "foo",
+                Version = "1.2.2"
+            };
             openApiDocument.Paths.Add(
                 "/test",
                 new OpenApiPathItem
@@ -38,11 +45,12 @@ public void ResponseMustHaveADescription()
             var walker = new OpenApiWalker(validator);
             walker.Walk(openApiDocument);
 
-            validator.Exceptions.ShouldBeEquivalentTo(
-                    new List<OpenApiException>
-                    { 
-                        new OpenApiException("Response must have a description")
-                    });
+            validator.Errors.ShouldBeEquivalentTo(
+                    new List<ValidationError>
+                    {
+                        new ValidationError(ErrorReason.Required, "#/description",
+                            String.Format(SRResource.Validation_FieldIsRequired, "description", "response"))
+        });
         }
     }
 }