Removing MvcViewEngineDescriptor and switching to use OptionsSetup to

setup RazorViewEngine.

Fixes #2269

src/Microsoft.AspNet.Mvc.Razor/MvcRazorMvcViewOptionsSetup.cs

@@ -1,21 +1,39 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System;
+using Microsoft.Framework.DependencyInjection;
+using Microsoft.Framework.Internal;
 using Microsoft.Framework.OptionsModel;
 
 namespace Microsoft.AspNet.Mvc.Razor
 {
+    /// <summary>
+    /// Configures <see cref="MvcViewOptions"/> to use <see cref="RazorViewEngine"/>.
+    /// </summary>
     public class MvcRazorMvcViewOptionsSetup : ConfigureOptions<MvcViewOptions>
     {
-        public MvcRazorMvcViewOptionsSetup()
-            : base(ConfigureMvc)
+        /// <summary>
+        /// Initializes a new instance of <see cref="MvcRazorMvcViewOptionsSetup"/>.
+        /// </summary>
+        /// <param name="serviceProvider">The application's <see cref="IServiceProvider"/>.</param>
+        public MvcRazorMvcViewOptionsSetup(IServiceProvider serviceProvider)
+            : base(options => ConfigureMvc(serviceProvider, options))
         {
             Order = DefaultOrder.DefaultFrameworkSortOrder;
         }
 
-        public static void ConfigureMvc(MvcViewOptions options)
+        /// <summary>
+        /// Configures <paramref name="options"/> to use <see cref="RazorViewEngine"/>.
+        /// </summary>
+        /// <param name="serviceProvider">The application's <see cref="IServiceProvider"/>.</param>
+        /// <param name="options">The <see cref="MvcViewOptions"/> to configure.</param>
+        public static void ConfigureMvc(
+            [NotNull] IServiceProvider serviceProvider,
+            [NotNull] MvcViewOptions options)
         {
-            options.ViewEngines.Add(typeof(RazorViewEngine));
+            var razorViewEngine = ActivatorUtilities.CreateInstance<RazorViewEngine>(serviceProvider);
+            options.ViewEngines.Add(razorViewEngine);
         }
     }
 }

src/Microsoft.AspNet.Mvc.ViewFeatures/DependencyInjection/MvcViewFeaturesMvcBuilderExtensions.cs

@@ -55,9 +55,7 @@ internal static void AddViewServices(IServiceCollection services)
             //
             // View Engine and related infrastructure
             //
-            // The provider is inexpensive to initialize and provides ViewEngines that may require request
-            // specific services.
-            services.TryAddScoped<ICompositeViewEngine, CompositeViewEngine>();
+            services.TryAddSingleton<ICompositeViewEngine, CompositeViewEngine>();
 
             // Support for activating ViewDataDictionary
             services.TryAddEnumerable(

src/Microsoft.AspNet.Mvc.ViewFeatures/MvcViewOptions.cs

@@ -19,10 +19,9 @@ public class MvcViewOptions
         public HtmlHelperOptions HtmlHelperOptions { get;[param: NotNull] set; } = new HtmlHelperOptions();
 
         /// <summary>
-        /// Gets a list of descriptors that represent <see cref="Rendering.IViewEngine"/> used
-        /// by this application.
+        /// Gets a list <see cref="IViewEngine"/>s used by this application.
         /// </summary>
-        public IList<ViewEngineDescriptor> ViewEngines { get; } = new List<ViewEngineDescriptor>();
+        public IList<IViewEngine> ViewEngines { get; } = new List<IViewEngine>();
 
         /// <summary>
         /// Gets a list of <see cref="IClientModelValidatorProvider"/> instances.

src/Microsoft.AspNet.Mvc.ViewFeatures/MvcViewOptionsSetup.cs

@@ -7,10 +7,13 @@
 namespace Microsoft.AspNet.Mvc
 {
     /// <summary>
-    /// Sets up default options for <see cref="MvcOptions"/>.
+    /// Sets up default options for <see cref="MvcViewOptions"/>.
     /// </summary>
     public class MvcViewOptionsSetup : ConfigureOptions<MvcViewOptions>
     {
+        /// <summary>
+        /// Initializes a new instance of <see cref="MvcRazorMvcViewOptionsSetup"/>.
+        /// </summary>
         public MvcViewOptionsSetup()
             : base(ConfigureMvc)
         {

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/ViewEngine/CompositeViewEngine.cs

@@ -1,7 +1,6 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
-using System;
 using System.Collections.Generic;
 using System.Linq;
 using Microsoft.Framework.Internal;
@@ -15,41 +14,14 @@ public class CompositeViewEngine : ICompositeViewEngine
         /// <summary>
         /// Initializes a new instance of <see cref="CompositeViewEngine"/>.
         /// </summary>
-        /// <param name="optionsAccessor">The options accessor for <see cref="MvcOptions"/>.</param>
-        /// <param name="typeActivatorCache">As <see cref="ITypeActivatorCache"/> instance that creates
-        /// an instance of type <see cref="IViewEngine"/>.</param>
-        /// <param name="serviceProvider">A <see cref="IServiceProvider"/> instance that retrieves services from the
-        /// service collection.</param>
-        public CompositeViewEngine(
-            IOptions<MvcViewOptions> optionsAccessor,
-            ITypeActivatorCache typeActivatorCache,
-            IServiceProvider serviceProvider)
+        /// <param name="optionsAccessor">The options accessor for <see cref="MvcViewOptions"/>.</param>
+        public CompositeViewEngine(IOptions<MvcViewOptions> optionsAccessor)
         {
-            var viewEngines = new List<IViewEngine>();
-            foreach (var descriptor in optionsAccessor.Options.ViewEngines)
-            {
-                IViewEngine viewEngine;
-                if (descriptor.ViewEngine != null)
-                {
-                    viewEngine = descriptor.ViewEngine;
-                }
-                else
-                {
-                    viewEngine = typeActivatorCache.CreateInstance<IViewEngine>(
-                        serviceProvider, 
-                        descriptor.ViewEngineType);
-                }
-
-                viewEngines.Add(viewEngine);
-            }
-
-            ViewEngines = viewEngines;
+            ViewEngines = optionsAccessor.Options.ViewEngines.ToArray();
         }
 
-        /// <summary>
-        /// Gets the list of <see cref="IViewEngine"/> this instance of <see cref="CompositeViewEngine"/> delegates to.
-        /// </summary>
-        public IReadOnlyList<IViewEngine> ViewEngines { get;  }
+        /// <inheritdoc />
+        public IReadOnlyList<IViewEngine> ViewEngines { get; }
 
         /// <inheritdoc />
         public ViewEngineResult FindPartialView([NotNull] ActionContext context,

src/Microsoft.AspNet.Mvc.ViewFeatures/Rendering/ViewEngine/ICompositeViewEngine.cs

@@ -1,12 +1,19 @@
 // Copyright (c) .NET Foundation. All rights reserved.
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
+using System.Collections.Generic;
+
 namespace Microsoft.AspNet.Mvc.Rendering
 {
     /// <summary>
     /// Represents an <see cref="IViewEngine"/> that delegates to one of a collection of view engines.
     /// </summary>
     public interface ICompositeViewEngine : IViewEngine
     {
+        /// <summary>
+        /// Gets the list of <see cref="IViewEngine"/> this instance of <see cref="ICompositeViewEngine"/> delegates
+        /// to.
+        /// </summary>
+        IReadOnlyList<IViewEngine> ViewEngines { get; }
     }
 }

test/Microsoft.AspNet.Mvc.Test/MvcOptionsSetupTest.cs

@@ -23,8 +23,8 @@ public void Setup_SetsUpViewEngines()
             var options = GetOptions<MvcViewOptions>();
 
             // Assert
-            Assert.Equal(1, options.ViewEngines.Count);
-            Assert.Equal(typeof(RazorViewEngine), options.ViewEngines[0].ViewEngineType);
+            var viewEngine = Assert.Single(options.ViewEngines);
+            Assert.IsType<RazorViewEngine>(viewEngine);
         }
 
         [Fact]