[Design] Split up MvcRouteHandler

This change splits up the conventional routing path from the attribute
routing path *inside* routing, instead of inside `MvcRouteHandler`. Each
attribute route group now gets its own instance of
`MvcAttributeRouteHandler` which just knows about the actions it can
reach.

This removes the concept of a route-group-token and removes the lookup
table entirely for attribute routing. This also means that the
`DefaultHandler` on `IRouteBuilder` will not be used for attribute routes,
which we are OK with for 1.0.0.

The action selector's functionality is now split into two methods. We
think this is OK for 1.0.0 because any customization of `IActionSelector`
up to now had to implement virtually the same policy as ours in order to
work with attribute routing. It should now be possible to customize the
selector in a meaningful way without interfering with attribute routing.

src/Microsoft.AspNetCore.Mvc.Abstractions/Abstractions/ActionDescriptor.cs

@@ -16,7 +16,6 @@ namespace Microsoft.AspNetCore.Mvc.Abstractions
             Id = Guid.NewGuid().ToString();
             Properties = new Dictionary<object, object>();
             RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
-            RouteValueDefaults = new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase);
         }
 
         /// <summary>
@@ -32,8 +31,6 @@ namespace Microsoft.AspNetCore.Mvc.Abstractions
 
         public AttributeRouteInfo AttributeRouteInfo { get; set; }
 
-        public IDictionary<string, object> RouteValueDefaults { get; set; }
-
         /// <summary>
         /// The set of constraints for this action. Must all be satisfied for the action to be selected.
         /// </summary>

src/Microsoft.AspNetCore.Mvc.Abstractions/ActionConstraints/ActionSelectorCandidate.cs

@@ -10,7 +10,7 @@ namespace Microsoft.AspNetCore.Mvc.ActionConstraints
     /// <summary>
     /// A candidate action for action selection.
     /// </summary>
-    public class ActionSelectorCandidate
+    public struct ActionSelectorCandidate
     {
         /// <summary>
         /// Creates a new <see cref="ActionSelectorCandidate"/>.
@@ -33,11 +33,11 @@ namespace Microsoft.AspNetCore.Mvc.ActionConstraints
         /// <summary>
         /// The <see cref="ActionDescriptor"/> representing a candiate for selection.
         /// </summary>
-        public ActionDescriptor Action { get; private set; }
+        public ActionDescriptor Action { get; }
 
         /// <summary>
         /// The list of <see cref="IActionConstraint"/> instances associated with <see name="Action"/>.
         /// </summary>
-        public IReadOnlyList<IActionConstraint> Constraints { get; private set; }
+        public IReadOnlyList<IActionConstraint> Constraints { get; }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/ApplicationModels/AttributeRouteModel.cs

@@ -198,7 +198,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
             return result.Substring(startIndex, subStringLength);
         }
 
-        public static string ReplaceTokens(string template, IDictionary<string, object> values)
+        public static string ReplaceTokens(string template, IDictionary<string, string> values)
         {
             var builder = new StringBuilder();
             var state = TemplateParserState.Plaintext;
@@ -340,7 +340,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
                                 .Replace("[[", "[")
                                 .Replace("]]", "]");
 
-                            object value;
+                            string value;
                             if (!values.TryGetValue(token, out value))
                             {
                                 // Value not found

src/Microsoft.AspNetCore.Mvc.Core/Builder/MvcApplicationBuilderExtensions.cs

@@ -3,9 +3,7 @@
 
 using System;
 using Microsoft.AspNetCore.Mvc.Core;
-using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.Internal;
-using Microsoft.AspNetCore.Mvc.Routing;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.Extensions.DependencyInjection;
 
@@ -94,11 +92,7 @@ namespace Microsoft.AspNetCore.Builder
 
             configureRoutes(routes);
 
-            // Adding the attribute route comes after running the user-code because
+            routes.Routes.Insert(0, AttributeRouting.CreateAttributeMegaRoute(app.ApplicationServices));
-            // we want to respect any changes to the DefaultHandler.
-            routes.Routes.Insert(0, AttributeRouting.CreateAttributeMegaRoute(
-                routes.DefaultHandler,
-                app.ApplicationServices));
 
             return app.UseRouter(routes.Build());
         }

src/Microsoft.AspNetCore.Mvc.Core/ConsumesAttribute.cs

@@ -142,7 +142,7 @@ namespace Microsoft.AspNetCore.Mvc
             }
 
             var firstCandidate = context.Candidates[0];
-            if (firstCandidate != context.CurrentCandidate)
+            if (firstCandidate.Action != context.CurrentCandidate.Action)
             {
                 // If the current candidate is not same as the first candidate,
                 // we need not probe other candidates to see if they apply.
@@ -157,7 +157,7 @@ namespace Microsoft.AspNetCore.Mvc
             // 3). If we have no matches, then we choose the first constraint to return true.It will later return a 415
             foreach (var candidate in context.Candidates)
             {
-                if (candidate == firstCandidate)
+                if (candidate.Action == firstCandidate.Action)
                 {
                     continue;
                 }

src/Microsoft.AspNetCore.Mvc.Core/DependencyInjection/MvcCoreServiceCollectionExtensions.cs

@@ -217,9 +217,10 @@ namespace Microsoft.Extensions.DependencyInjection
             services.TryAddSingleton<RedirectToRouteResultExecutor>();
 
             //
-            // Setup default handler
+            // Route Handlers
             //
-            services.TryAddSingleton<MvcRouteHandler>();
+            services.TryAddSingleton<MvcRouteHandler>(); // Only one per app
+            services.TryAddTransient<MvcAttributeRouteHandler>(); // Many per app
         }
 
         private static void ConfigureDefaultServices(IServiceCollection services)

src/Microsoft.AspNetCore.Mvc.Core/Infrastructure/IActionSelector.cs

@@ -1,6 +1,7 @@
 // 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;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Routing;
 
@@ -12,13 +13,44 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
     public interface IActionSelector
     {
         /// <summary>
-        /// Selects an <see cref="ActionDescriptor"/> for the request associated with <paramref name="context"/>.
+        /// Selects a set of <see cref="ActionDescriptor"/> candidates for the current request associated with
+        /// <paramref name="context"/>.
         /// </summary>
-        /// <param name="context">The <see cref="RouteContext"/> for the current request.</param>
+        /// <param name="context">The <see cref="RouteContext"/> associated with the current request.</param>
-        /// <returns>An <see cref="ActionDescriptor"/> or <c>null</c> if no action can be selected.</returns>
+        /// <returns>A set of <see cref="ActionDescriptor"/> candidates or <c>null</c>.</returns>
+        /// <remarks>
+        /// <para>
+        /// Used by conventional routing to select the set of actions that match the route values for the
+        /// current request. Action constraints associated with the candidates are not invoked by this method
+        /// </para>
+        /// <para>
+        /// Attribute routing does not call this method.
+        /// </para>
+        /// </remarks>
+        IReadOnlyList<ActionDescriptor> SelectCandidates(RouteContext context);
+
+        /// <summary>
+        /// Selects the best <see cref="ActionDescriptor"/> candidate from <paramref name="candidates"/> for the 
+        /// current request associated with <paramref name="context"/>.
+        /// </summary>
+        /// <param name="context">The <see cref="RouteContext"/> associated with the current request.</param>
+        /// <param name="candidates">The set of <see cref="ActionDescriptor"/> candidates.</param>
+        /// <returns>The best <see cref="ActionDescriptor"/> candidate for the current request or <c>null</c>.</returns>
         /// <exception cref="Internal.AmbiguousActionException">
         /// Thrown when action selection results in an ambiguity.
         /// </exception>
-        ActionDescriptor Select(RouteContext context);
+        /// <remarks>
+        /// <para>
+        /// Invokes action constraints associated with the candidates.
+        /// </para>
+        /// <para>
+        /// Used by conventional routing after calling <see cref="SelectCandidates"/> to apply action constraints and
+        /// disambiguate between multiple candidates.
+        /// </para>
+        /// <para>
+        /// Used by attribute routing to apply action constraints and disambiguate between multiple candidates.
+        /// </para>
+        /// </remarks>
+        ActionDescriptor SelectBestCandidate(RouteContext context, IReadOnlyList<ActionDescriptor> candidates);
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/Internal/ActionSelectionDecisionTree.cs

@@ -6,9 +6,9 @@ using System.Collections.Generic;
 #if NET451
 using System.ComponentModel;
 #endif
+using System.Linq;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
-using Microsoft.AspNetCore.Mvc.Routing;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Routing.DecisionTree;
 
@@ -27,8 +27,9 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         {
             Version = actions.Version;
 
+            var conventionalRoutedActions = actions.Items.Where(a => a.AttributeRouteInfo?.Template == null).ToArray();
             _root = DecisionTreeBuilder<ActionDescriptor>.GenerateTree(
-                actions.Items,
+                conventionalRoutedActions,
                 new ActionDescriptorClassifier());
         }
 

src/Microsoft.AspNetCore.Mvc.Core/Internal/ActionSelector.cs

@@ -39,8 +39,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             _actionConstraintCache = actionConstraintCache;
         }
 
-        /// <inheritdoc />
+        public IReadOnlyList<ActionDescriptor> SelectCandidates(RouteContext context)
-        public ActionDescriptor Select(RouteContext context)
         {
             if (context == null)
             {
@@ -48,35 +47,24 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             }
 
             var tree = _decisionTreeProvider.DecisionTree;
-            var matchingRouteValues = tree.Select(context.RouteData.Values);
+            return tree.Select(context.RouteData.Values);
+        }
 
-            var candidates = new List<ActionSelectorCandidate>();
+        public ActionDescriptor SelectBestCandidate(RouteContext context, IReadOnlyList<ActionDescriptor> candidates)
-
+        {
-            // Perf: Avoid allocations
+            if (context == null)
-            for (var i = 0; i < matchingRouteValues.Count; i++)
             {
-                var action = matchingRouteValues[i];
+                throw new ArgumentNullException(nameof(context));
-                var constraints = _actionConstraintCache.GetActionConstraints(context.HttpContext, action);
-                candidates.Add(new ActionSelectorCandidate(action, constraints));
             }
 
-            var matchingActionConstraints =
+            if (candidates == null)
-                EvaluateActionConstraints(context, candidates, startingOrder: null);
-
-            List<ActionDescriptor> matchingActions = null;
-            if (matchingActionConstraints != null)
             {
-                matchingActions = new List<ActionDescriptor>(matchingActionConstraints.Count);
+                throw new ArgumentNullException(nameof(candidates));
-                // Perf: Avoid allocations
-                for (var i = 0; i < matchingActionConstraints.Count; i++)
-                {
-                    var candidate = matchingActionConstraints[i];
-                    matchingActions.Add(candidate.Action);
-                }
             }
 
-            var finalMatches = SelectBestActions(matchingActions);
+            var matches = EvaluateActionConstraints(context, candidates);
 
+            var finalMatches = SelectBestActions(matches);
             if (finalMatches == null || finalMatches.Count == 0)
             {
                 return null;
@@ -113,7 +101,38 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             return actions;
         }
 
-        private IReadOnlyList<ActionSelectorCandidate> EvaluateActionConstraints(
+        private IReadOnlyList<ActionDescriptor> EvaluateActionConstraints(
+            RouteContext context,
+            IReadOnlyList<ActionDescriptor> actions)
+        {
+            var candidates = new List<ActionSelectorCandidate>();
+
+            // Perf: Avoid allocations
+            for (var i = 0; i < actions.Count; i++)
+            {
+                var action = actions[i];
+                var constraints = _actionConstraintCache.GetActionConstraints(context.HttpContext, action);
+                candidates.Add(new ActionSelectorCandidate(action, constraints));
+            }
+
+            var matches = EvaluateActionConstraintsCore(context, candidates, startingOrder: null);
+
+            List<ActionDescriptor> results = null;
+            if (matches != null)
+            {
+                results = new List<ActionDescriptor>(matches.Count);
+                // Perf: Avoid allocations
+                for (var i = 0; i < matches.Count; i++)
+                {
+                    var candidate = matches[i];
+                    results.Add(candidate.Action);
+                }
+            }
+
+            return results;
+        }
+
+        private IReadOnlyList<ActionSelectorCandidate> EvaluateActionConstraintsCore(
             RouteContext context,
             IReadOnlyList<ActionSelectorCandidate> candidates,
             int? startingOrder)
@@ -198,7 +217,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             // If we have matches with constraints, those are 'better' so try to keep processing those
             if (actionsWithConstraint.Count > 0)
             {
-                var matches = EvaluateActionConstraints(context, actionsWithConstraint, order);
+                var matches = EvaluateActionConstraintsCore(context, actionsWithConstraint, order);
                 if (matches?.Count > 0)
                 {
                     return matches;
@@ -212,7 +231,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             }
             else
             {
-                return EvaluateActionConstraints(context, actionsWithoutConstraint, order);
+                return EvaluateActionConstraintsCore(context, actionsWithoutConstraint, order);
             }
         }
     }

src/Microsoft.AspNetCore.Mvc.Core/Internal/AttributeRoute.cs

@@ -8,32 +8,27 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.Core;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
-using Microsoft.AspNetCore.Mvc.Routing;
 using Microsoft.AspNetCore.Routing;
 using Microsoft.AspNetCore.Routing.Template;
 using Microsoft.AspNetCore.Routing.Tree;
 using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Internal;
 
 namespace Microsoft.AspNetCore.Mvc.Internal
 {
     public class AttributeRoute : IRouter
     {
-        private readonly IRouter _handler;
         private readonly IActionDescriptorCollectionProvider _actionDescriptorCollectionProvider;
         private readonly IServiceProvider _services;
+        private readonly Func<ActionDescriptor[], IRouter> _handlerFactory;
 
         private TreeRouter _router;
 
         public AttributeRoute(
-            IRouter handler,
             IActionDescriptorCollectionProvider actionDescriptorCollectionProvider,
-            IServiceProvider services)
+            IServiceProvider services,
+            Func<ActionDescriptor[], IRouter> handlerFactory)
         {
-            if (handler == null)
-            {
-                throw new ArgumentNullException(nameof(handler));
-            }
-
             if (actionDescriptorCollectionProvider == null)
             {
                 throw new ArgumentNullException(nameof(actionDescriptorCollectionProvider));
@@ -44,9 +39,14 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 throw new ArgumentNullException(nameof(services));
             }
 
-            _handler = handler;
+            if (handlerFactory == null)
+            {
+                _handlerFactory = handlerFactory;
+            }
+
             _actionDescriptorCollectionProvider = actionDescriptorCollectionProvider;
             _services = services;
+            _handlerFactory = handlerFactory;
         }
 
         /// <inheritdoc />
@@ -88,10 +88,18 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             // action by expected route values, and then use the TemplateBinder to generate the link.
             foreach (var routeInfo in routeInfos)
             {
+                var defaults = new RouteValueDictionary();
+                foreach (var kvp in routeInfo.ActionDescriptor.RouteValues)
+                {
+                    defaults.Add(kvp.Key, kvp.Value);
+                }
+
+                // We use the `NullRouter` as the route handler because we don't need to do anything for link
+                // generations. The TreeRouter does it all for us.
                 builder.MapOutbound(
-                    _handler,
+                    NullRouter.Instance,
                     routeInfo.RouteTemplate, 
-                    new RouteValueDictionary(routeInfo.ActionDescriptor.RouteValueDefaults),
+                    defaults,
                     routeInfo.RouteName, 
                     routeInfo.Order);
             }
@@ -99,37 +107,27 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             // We're creating one AttributeRouteMatchingEntry per group, so we need to identify the distinct set of
             // groups. It's guaranteed that all members of the group have the same template and precedence,
             // so we only need to hang on to a single instance of the RouteInfo for each group.
-            var distinctRouteInfosByGroup = GroupRouteInfosByGroupId(routeInfos);
+            var groups = GroupRouteInfos(routeInfos);
-            foreach (var routeInfo in distinctRouteInfosByGroup)
+            foreach (var group in groups)
             {
+                var handler = _handlerFactory(group.ToArray());
+
                 // Note that because we only support 'inline' defaults, each routeInfo group also has the same
                 // set of defaults. 
                 //
                 // We then inject the route group as a default for the matcher so it gets passed back to MVC
                 // for use in action selection.
-                var entry = builder.MapInbound(
+                builder.MapInbound(
-                    _handler,
+                    handler,
-                    routeInfo.RouteTemplate,
+                    group.Key.RouteTemplate,
-                    routeInfo.RouteName,
+                    group.Key.RouteName,
-                    routeInfo.Order);
+                    group.Key.Order);
-
-                entry.Defaults[TreeRouter.RouteGroupKey] = routeInfo.RouteGroup;
             }
         }
 
-        private static IEnumerable<RouteInfo> GroupRouteInfosByGroupId(List<RouteInfo> routeInfos)
+        private static IEnumerable<IGrouping<RouteInfo, ActionDescriptor>> GroupRouteInfos(List<RouteInfo> routeInfos)
         {
-            var routeInfosByGroupId = new Dictionary<string, RouteInfo>(StringComparer.OrdinalIgnoreCase);
+            return routeInfos.GroupBy(r => r, r => r.ActionDescriptor, RouteInfoEqualityComparer.Instance);
-
-            foreach (var routeInfo in routeInfos)
-            {
-                if (!routeInfosByGroupId.ContainsKey(routeInfo.RouteGroup))
-                {
-                    routeInfosByGroupId.Add(routeInfo.RouteGroup, routeInfo);
-                }
-            }
-
-            return routeInfosByGroupId.Values;
         }
 
         private static List<RouteInfo> GetRouteInfos(IReadOnlyList<ActionDescriptor> actions)
@@ -179,23 +177,9 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             Dictionary<string, RouteTemplate> templateCache,
             ActionDescriptor action)
         {
-            string value;
-            action.RouteValues.TryGetValue(TreeRouter.RouteGroupKey, out value);
-
-            if (string.IsNullOrEmpty(value))
-            {
-                // This can happen if an ActionDescriptor has a route template, but doesn't have one of our
-                // special route group constraints. This is a good indication that the user is using a 3rd party
-                // routing system, or has customized their ADs in a way that we can no longer understand them.
-                //
-                // We just treat this case as an 'opt-out' of our attribute routing system.
-                return null;
-            }
-
             var routeInfo = new RouteInfo()
             {
                 ActionDescriptor = action,
-                RouteGroup = value,
             };
 
             try
@@ -216,7 +200,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 return routeInfo;
             }
 
-            foreach (var kvp in action.RouteValueDefaults)
+            foreach (var kvp in action.RouteValues)
             {
                 foreach (var parameter in routeInfo.RouteTemplate.Parameters)
                 {
@@ -246,11 +230,66 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             
             public int Order { get; set; }
 
-            public string RouteGroup { get; set; }
-
             public string RouteName { get; set; }
 
             public RouteTemplate RouteTemplate { get; set; }
         }
+
+        private class RouteInfoEqualityComparer : IEqualityComparer<RouteInfo>
+        {
+            public static readonly RouteInfoEqualityComparer Instance = new RouteInfoEqualityComparer();
+
+            public bool Equals(RouteInfo x, RouteInfo y)
+            {
+                if (x == null && y == null)
+                {
+                    return true;
+                }
+                else if (x == null ^ y == null)
+                {
+                    return false;
+                }
+                else if (x.Order != y.Order)
+                {
+                    return false;
+                }
+                else
+                {
+                    return string.Equals(
+                        x.RouteTemplate.TemplateText,
+                        y.RouteTemplate.TemplateText,
+                        StringComparison.OrdinalIgnoreCase);
+                }
+            }
+
+            public int GetHashCode(RouteInfo obj)
+            {
+                if (obj == null)
+                {
+                    return 0;
+                }
+
+                var hash = new HashCodeCombiner();
+                hash.Add(obj.Order);
+                hash.Add(obj.RouteTemplate.TemplateText, StringComparer.OrdinalIgnoreCase);
+                return hash;
+            }
+        }
+
+        // Used only to hook up link generation, and it doesn't need to do anything.
+        private class NullRouter : IRouter
+        {
+            public static readonly NullRouter Instance = new NullRouter();
+
+            public VirtualPathData GetVirtualPath(VirtualPathContext context)
+            {
+                return null;
+            }
+
+            public Task RouteAsync(RouteContext context)
+            {
+                throw new NotImplementedException();
+            }
+        }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/Internal/AttributeRouting.cs

@@ -13,25 +13,24 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         /// <summary>
         /// Creates an attribute route using the provided services and provided target router.
         /// </summary>
-        /// <param name="target">The router to invoke when a route entry matches.</param>
         /// <param name="services">The application services.</param>
         /// <returns>An attribute route.</returns>
-        public static IRouter CreateAttributeMegaRoute(IRouter target, IServiceProvider services)
+        public static IRouter CreateAttributeMegaRoute(IServiceProvider services)
         {
-            if (target == null)
-            {
-                throw new ArgumentNullException(nameof(target));
-            }
-
             if (services == null)
             {
                 throw new ArgumentNullException(nameof(services));
             }
 
             return new AttributeRoute(
-                target,
                 services.GetRequiredService<IActionDescriptorCollectionProvider>(),
-                services);
+                services,
+                actions => 
+                {
+                    var handler = services.GetRequiredService<MvcAttributeRouteHandler>();
+                    handler.Actions = actions;
+                    return handler;
+                });
         }
     }
 }

src/Microsoft.AspNetCore.Mvc.Core/Internal/ControllerActionDescriptorBuilder.cs

@@ -36,7 +36,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         {
             var actions = new List<ControllerActionDescriptor>();
 
-            var hasAttributeRoutes = false;
             var routeValueKeys = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
 
             var methodInfoMap = new MethodToActionMap();
@@ -71,21 +70,12 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         AddProperties(actionDescriptor, action, controller, application);
 
                         actionDescriptor.BoundProperties = controllerPropertyDescriptors;
+
                         if (IsAttributeRoutedAction(actionDescriptor))
                         {
-                            hasAttributeRoutes = true;
-
-                            // An attribute routed action will ignore conventional routed constraints. We still
-                            // want to provide these values as ambient values for link generation.
-                            AddRouteValuesAsDefaultRouteValues(actionDescriptor);
-
                             // Replaces tokens like [controller]/[action] in the route template with the actual values
                             // for this action.
                             ReplaceAttributeRouteTokens(actionDescriptor, routeTemplateErrors);
-
-                            // Attribute routed actions will ignore conventional routed values. Instead they have
-                            // a single route value "RouteGroup" associated with it.
-                            ReplaceRouteValues(actionDescriptor);
                         }
                     }
 
@@ -113,44 +103,19 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     validatedMethods.Add(actionDescriptor.MethodInfo);
                 }
 
-                if (!IsAttributeRoutedAction(actionDescriptor))
+                var attributeRouteInfo = actionDescriptor.AttributeRouteInfo;
+                if (attributeRouteInfo?.Name != null)
                 {
-                    // Any attribute routes are in use, then non-attribute-routed action descriptors can't be
+                    // Build a map of attribute route name to action descriptors to ensure that all
-                    // selected when a route group returned by the route.
+                    // attribute routes with a given name have the same template.
-                    if (hasAttributeRoutes)
+                    AddActionToNamedGroup(actionsByRouteName, attributeRouteInfo.Name, actionDescriptor);
-                    {
-                        actionDescriptor.RouteValues.Add(TreeRouter.RouteGroupKey, string.Empty);
-                    }
-
-                    // Add a route value with 'null' for each user-defined route value in the set to all the
-                    // actions that don't have that value. For example, if a controller defines
-                    // an area, all actions that don't belong to an area must have a route
-                    // value that prevents them from matching an incoming request when area is specified.
-                    AddGlobalRouteValues(actionDescriptor, routeValueKeys);
                 }
-                else
-                {
-                    var attributeRouteInfo = actionDescriptor.AttributeRouteInfo;
-                    if (attributeRouteInfo.Name != null)
-                    {
-                        // Build a map of attribute route name to action descriptors to ensure that all
-                        // attribute routes with a given name have the same template.
-                        AddActionToNamedGroup(actionsByRouteName, attributeRouteInfo.Name, actionDescriptor);
-                    }
 
-                    // We still want to add a 'null' for any constraint with DenyKey so that link generation
+                // Add a route value with 'null' for each user-defined route value in the set to all the
-                    // works properly.
+                // actions that don't have that value. For example, if a controller defines
-                    //
+                // an area, all actions that don't belong to an area must have a route
-                    // Consider an action like { area = "", controller = "Home", action = "Index" }. Even if
+                // value that prevents them from matching an incoming request when area is specified.
-                    // it's attribute routed, it needs to know that area must be null to generate a link.
+                AddGlobalRouteValues(actionDescriptor, routeValueKeys);
-                    foreach (var key in routeValueKeys)
-                    {
-                        if (!actionDescriptor.RouteValueDefaults.ContainsKey(key))
-                        {
-                            actionDescriptor.RouteValueDefaults.Add(key, value: null);
-                        }
-                    }
-                }
             }
 
             if (attributeRoutingConfigurationErrors.Any())
@@ -459,7 +424,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             foreach (var kvp in action.RouteValues)
             {
                 keys.Add(kvp.Key);
-                
+
                 // Skip duplicates
                 if (!actionDescriptor.RouteValues.ContainsKey(kvp.Key))
                 {
@@ -490,16 +455,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             }
         }
 
-        private static void ReplaceRouteValues(ControllerActionDescriptor actionDescriptor)
-        {
-            var routeGroupValue = GetRouteGroupValue(
-                actionDescriptor.AttributeRouteInfo.Order,
-                actionDescriptor.AttributeRouteInfo.Template);
-
-            actionDescriptor.RouteValues.Clear();
-            actionDescriptor.RouteValues.Add(TreeRouter.RouteGroupKey, routeGroupValue);
-        }
-
         private static void ReplaceAttributeRouteTokens(
             ControllerActionDescriptor actionDescriptor,
             IList<string> routeTemplateErrors)
@@ -508,13 +463,13 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             {
                 actionDescriptor.AttributeRouteInfo.Template = AttributeRouteModel.ReplaceTokens(
                     actionDescriptor.AttributeRouteInfo.Template,
-                    actionDescriptor.RouteValueDefaults);
+                    actionDescriptor.RouteValues);
 
                 if (actionDescriptor.AttributeRouteInfo.Name != null)
                 {
                     actionDescriptor.AttributeRouteInfo.Name = AttributeRouteModel.ReplaceTokens(
                         actionDescriptor.AttributeRouteInfo.Name,
-                        actionDescriptor.RouteValueDefaults);
+                        actionDescriptor.RouteValues);
                 }
             }
             catch (InvalidOperationException ex)
@@ -530,14 +485,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             }
         }
 
-        private static void AddRouteValuesAsDefaultRouteValues(ControllerActionDescriptor actionDescriptor)
-        {
-            foreach (var kvp in actionDescriptor.RouteValues)
-            {
-                actionDescriptor.RouteValueDefaults.Add(kvp.Key, kvp.Value);
-            }
-        }
-
         private static void AddGlobalRouteValues(
             ControllerActionDescriptor actionDescriptor,
             ISet<string> removalConstraints)
@@ -731,12 +678,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             return message;
         }
 
-        private static string GetRouteGroupValue(int order, string template)
-        {
-            var group = string.Format(CultureInfo.InvariantCulture, "{0}-{1}", order, template);
-            return ("__route__" + group).ToUpperInvariant();
-        }
-
         // We need to build a map of methods to reflected actions and reflected actions to
         // action descriptors so that we can validate later that no method produced attribute
         // and non attributed actions at the same time, and that no method that produced attribute

src/Microsoft.AspNetCore.Mvc.Core/Internal/MvcAttributeRouteHandler.cs

@@ -0,0 +1,117 @@
+// 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.Diagnostics;
+using System.Threading.Tasks;
+using Microsoft.AspNetCore.Http;
+using Microsoft.AspNetCore.Mvc.Abstractions;
+using Microsoft.AspNetCore.Mvc.Core;
+using Microsoft.AspNetCore.Mvc.Infrastructure;
+using Microsoft.AspNetCore.Routing;
+using Microsoft.Extensions.Logging;
+
+namespace Microsoft.AspNetCore.Mvc.Internal
+{
+    public class MvcAttributeRouteHandler : IRouter
+    {
+        private IActionContextAccessor _actionContextAccessor;
+        private IActionInvokerFactory _actionInvokerFactory;
+        private IActionSelector _actionSelector;
+        private ILogger _logger;
+        private DiagnosticSource _diagnosticSource;
+
+        public MvcAttributeRouteHandler(
+            IActionInvokerFactory actionInvokerFactory,
+            IActionSelector actionSelector,
+            DiagnosticSource diagnosticSource,
+            ILoggerFactory loggerFactory)
+            : this(actionInvokerFactory, actionSelector, diagnosticSource, loggerFactory, actionContextAccessor: null)
+        {
+        }
+
+        public MvcAttributeRouteHandler(
+            IActionInvokerFactory actionInvokerFactory,
+            IActionSelector actionSelector,
+            DiagnosticSource diagnosticSource,
+            ILoggerFactory loggerFactory,
+            IActionContextAccessor actionContextAccessor)
+        {
+            // The IActionContextAccessor is optional. We want to avoid the overhead of using CallContext
+            // if possible.
+            _actionContextAccessor = actionContextAccessor;
+
+            _actionInvokerFactory = actionInvokerFactory;
+            _actionSelector = actionSelector;
+            _diagnosticSource = diagnosticSource;
+            _logger = loggerFactory.CreateLogger<MvcAttributeRouteHandler>();
+        }
+
+        public ActionDescriptor[] Actions { get; set; }
+
+        public VirtualPathData GetVirtualPath(VirtualPathContext context)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            // We return null here because we're not responsible for generating the url, the route is.
+            return null;
+        }
+
+        public Task RouteAsync(RouteContext context)
+        {
+            if (context == null)
+            {
+                throw new ArgumentNullException(nameof(context));
+            }
+
+            if (Actions == null)
+            {
+                var message = Resources.FormatPropertyOfTypeCannotBeNull(
+                    nameof(Actions), 
+                    nameof(MvcAttributeRouteHandler));
+                throw new InvalidOperationException(message);
+            }
+
+            var actionDescriptor = _actionSelector.SelectBestCandidate(context, Actions);
+            if (actionDescriptor == null)
+            {
+                _logger.NoActionsMatched();
+                return TaskCache.CompletedTask;
+            }
+
+            foreach (var kvp in actionDescriptor.RouteValues)
+            {
+                if (!string.IsNullOrEmpty(kvp.Value))
+                {
+                    context.RouteData.Values[kvp.Key] = kvp.Value;
+                }
+            }
+
+            context.Handler = (c) =>
+            {
+                var routeData = c.GetRouteData();
+
+                var actionContext = new ActionContext(context.HttpContext, routeData, actionDescriptor);
+                if (_actionContextAccessor != null)
+                {
+                    _actionContextAccessor.ActionContext = actionContext;
+                }
+
+                var invoker = _actionInvokerFactory.CreateInvoker(actionContext);
+                if (invoker == null)
+                {
+                    throw new InvalidOperationException(
+                        Resources.FormatActionInvokerFactory_CouldNotCreateInvoker(
+                            actionDescriptor.DisplayName));
+                }
+
+                return invoker.InvokeAsync();
+            };
+
+            return TaskCache.CompletedTask;
+        }
+    }
+}

src/Microsoft.AspNetCore.Mvc.Core/Internal/MvcRouteHandler.cs

@@ -7,7 +7,6 @@ using System.Threading.Tasks;
 using Microsoft.AspNetCore.Mvc.Core;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Routing;
-using Microsoft.AspNetCore.Routing.Tree;
 using Microsoft.Extensions.Logging;
 
 namespace Microsoft.AspNetCore.Mvc.Internal
@@ -64,28 +63,21 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 throw new ArgumentNullException(nameof(context));
             }
 
-            var actionDescriptor = _actionSelector.Select(context);
+            var candidates = _actionSelector.SelectCandidates(context);
+            if (candidates == null || candidates.Count == 0)
+            {
+                _logger.NoActionsMatched();
+                return TaskCache.CompletedTask;
+            }
+
+            var actionDescriptor = _actionSelector.SelectBestCandidate(context, candidates);
             if (actionDescriptor == null)
             {
                 _logger.NoActionsMatched();
                 return TaskCache.CompletedTask;
             }
 
-            if (actionDescriptor.RouteValueDefaults != null)
+            context.Handler = (c) =>
-            {
-                foreach (var kvp in actionDescriptor.RouteValueDefaults)
-                {
-                    if (!context.RouteData.Values.ContainsKey(kvp.Key))
-                    {
-                        context.RouteData.Values.Add(kvp.Key, kvp.Value);
-                    }
-                }
-
-                // Removing RouteGroup from RouteValues to simulate the result of conventional routing
-                context.RouteData.Values.Remove(TreeRouter.RouteGroupKey);
-            }
-
-            context.Handler = async (c) =>
             {
                 var routeData = c.GetRouteData();
 
@@ -103,10 +95,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                             actionDescriptor.DisplayName));
                 }
 
-                await invoker.InvokeAsync();
+                return invoker.InvokeAsync();
             };
 
             return TaskCache.CompletedTask;
         }
     }
-}
+}

src/Microsoft.AspNetCore.Mvc.Razor/RazorViewEngine.cs

@@ -91,8 +91,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor
         /// <remarks>
         /// The casing of a route value in <see cref="ActionContext.RouteData"/> is determined by the client.
         /// This making constructing paths for view locations in a case sensitive file system unreliable. Using the
-        /// <see cref="Abstractions.ActionDescriptor.RouteValueDefaults"/> for attribute routes and
+        /// <see cref="Abstractions.ActionDescriptor.RouteValues"/> to get route values
-        /// <see cref="Abstractions.ActionDescriptor.RouteValues"/> for traditional routes to get route values
         /// produces consistently cased results.
         /// </remarks>
         public static string GetNormalizedRouteValue(ActionContext context, string key)
@@ -115,22 +114,12 @@ namespace Microsoft.AspNetCore.Mvc.Razor
 
             var actionDescriptor = context.ActionDescriptor;
             string normalizedValue = null;
-            if (actionDescriptor.AttributeRouteInfo != null)
+
+            string value;
+            if (actionDescriptor.RouteValues.TryGetValue(key, out value) &&
+                !string.IsNullOrEmpty(value))
             {
-                object match;
+                normalizedValue = value;
-                if (actionDescriptor.RouteValueDefaults.TryGetValue(key, out match))
-                {
-                    normalizedValue = match?.ToString();
-                }
-            }
-            else
-            {
-                string value;
-                if (actionDescriptor.RouteValues.TryGetValue(key, out value) &&
-                    !string.IsNullOrEmpty(value))
-                {
-                    normalizedValue = value;
-                }
             }
 
             var stringRouteValue = routeValue?.ToString();

src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/PartialViewResultExecutor.cs

@@ -179,22 +179,11 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
 
             var actionDescriptor = context.ActionDescriptor;
             string normalizedValue = null;
-            if (actionDescriptor.AttributeRouteInfo != null)
+            string value;
+            if (actionDescriptor.RouteValues.TryGetValue(ActionNameKey, out value) &&
+                !string.IsNullOrEmpty(value))
             {
-                object match;
+                normalizedValue = value;
-                if (actionDescriptor.RouteValueDefaults.TryGetValue(ActionNameKey, out match))
-                {
-                    normalizedValue = match?.ToString();
-                }
-            }
-            else
-            {
-                string value;
-                if (actionDescriptor.RouteValues.TryGetValue(ActionNameKey, out value) &&
-                    !string.IsNullOrEmpty(value))
-                {
-                    normalizedValue = value;
-                }
             }
 
             var stringRouteValue = routeValue?.ToString();

src/Microsoft.AspNetCore.Mvc.ViewFeatures/Internal/ViewResultExecutor.cs

@@ -193,22 +193,11 @@ namespace Microsoft.AspNetCore.Mvc.ViewFeatures.Internal
 
             var actionDescriptor = context.ActionDescriptor;
             string normalizedValue = null;
-            if (actionDescriptor.AttributeRouteInfo != null)
+            string value;
+            if (actionDescriptor.RouteValues.TryGetValue(ActionNameKey, out value) &&
+                !string.IsNullOrEmpty(value))
             {
-                object match;
+                normalizedValue = value;
-                if (actionDescriptor.RouteValueDefaults.TryGetValue(ActionNameKey, out match))
-                {
-                    normalizedValue = match?.ToString();
-                }
-            }
-            else
-            {
-                string value;
-                if (actionDescriptor.RouteValues.TryGetValue(ActionNameKey, out value) &&
-                    !string.IsNullOrEmpty(value))
-                {
-                    normalizedValue = value;
-                }
             }
 
             var stringRouteValue = routeValue?.ToString();

test/Microsoft.AspNetCore.Mvc.Core.Test/ApplicationModel/AttributeRouteModelTests.cs

@@ -146,17 +146,11 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
 
         [Theory]
         [MemberData(nameof(ReplaceTokens_ValueValuesData))]
-        public void ReplaceTokens_ValidValues(string template, object values, string expected)
+        public void ReplaceTokens_ValidValues(string template, Dictionary<string, string> values, string expected)
         {
             // Arrange
-            var valuesDictionary = values as IDictionary<string, object>;
-            if (valuesDictionary == null)
-            {
-                valuesDictionary = new RouteValueDictionary(values);
-            }
-
             // Act
-            var result = AttributeRouteModel.ReplaceTokens(template, valuesDictionary);
+            var result = AttributeRouteModel.ReplaceTokens(template, values);
 
             // Assert
             Assert.Equal(expected, result);
@@ -164,15 +158,9 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
 
         [Theory]
         [MemberData(nameof(ReplaceTokens_InvalidFormatValuesData))]
-        public void ReplaceTokens_InvalidFormat(string template, object values, string reason)
+        public void ReplaceTokens_InvalidFormat(string template, Dictionary<string, string> values, string reason)
         {
             // Arrange
-            var valuesDictionary = values as IDictionary<string, object>;
-            if (valuesDictionary == null)
-            {
-                valuesDictionary = new RouteValueDictionary(values);
-            }
-
             var expected = string.Format(
                 "The route template '{0}' has invalid syntax. {1}",
                 template,
@@ -180,7 +168,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
 
             // Act
             var ex = Assert.Throws<InvalidOperationException>(
-                () => { AttributeRouteModel.ReplaceTokens(template, valuesDictionary); });
+                () => { AttributeRouteModel.ReplaceTokens(template, values); });
 
             // Assert
             Assert.Equal(expected, ex.Message);
@@ -191,7 +179,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
         {
             // Arrange
             var template = "[area]/[controller]/[action2]";
-            var values = new RouteValueDictionary()
+            var values = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
             {
                 { "area", "Help" },
                 { "controller", "Admin" },
@@ -428,49 +416,73 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
                 yield return new object[]
                 {
                     "[controller]/[action]",
-                    new { controller = "Home", action = "Index" },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
                     "Home/Index"
                 };
 
                 yield return new object[]
                 {
                     "[controller]",
-                    new { controller = "Home", action = "Index" },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
                     "Home"
                 };
 
                 yield return new object[]
                 {
                     "[controller][[",
-                    new { controller = "Home", action = "Index" },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
                     "Home["
                 };
 
                 yield return new object[]
                 {
                     "[coNTroller]",
-                    new { contrOLler = "Home", action = "Index" },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
                     "Home"
                 };
 
                 yield return new object[]
                 {
                     "thisisSomeText[action]",
-                    new { controller = "Home", action = "Index" },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
                     "thisisSomeTextIndex"
                 };
 
                 yield return new object[]
                 {
                     "[[-]][[/[[controller]]",
-                    new { controller = "Home", action = "Index" },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
                     "[-][/[controller]"
                 };
 
                 yield return new object[]
                 {
                     "[contr[[oller]/[act]]ion]",
-                    new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase)
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
                     {
                         { "contr[oller", "Home" },
                         { "act]ion", "Index" }
@@ -481,7 +493,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
                 yield return new object[]
                 {
                     "[controller][action]",
-                    new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase)
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
                     {
                         { "controller", "Home" },
                         { "action", "Index" }
@@ -492,7 +504,7 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
                 yield return new object[]
                 {
                     "[contr}oller]/[act{ion]/{id}",
-                    new Dictionary<string, object>(StringComparer.OrdinalIgnoreCase)
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
                     {
                         { "contr}oller", "Home" },
                         { "act{ion", "Index" }
@@ -509,35 +521,35 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
                 yield return new object[]
                 {
                     "[",
-                    new { },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
                     "A replacement token is not closed."
                 };
 
                 yield return new object[]
                 {
                     "text]",
-                    new { },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
                     "Token delimiters ('[', ']') are imbalanced.",
                 };
 
                 yield return new object[]
                 {
                     "text]morecooltext",
-                    new { },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
                     "Token delimiters ('[', ']') are imbalanced.",
                 };
 
                 yield return new object[]
                 {
                     "[action",
-                    new { },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
                     "A replacement token is not closed.",
                 };
 
                 yield return new object[]
                 {
                     "[action]]][",
-                    new RouteValueDictionary()
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
                     {
                         { "action]", "Index" }
                     },
@@ -547,21 +559,21 @@ namespace Microsoft.AspNetCore.Mvc.ApplicationModels
                 yield return new object[]
                 {
                     "[action]]",
-                    new { },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
                     "A replacement token is not closed."
                 };
 
                 yield return new object[]
                 {
                     "[ac[tion]",
-                    new { },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
                     "An unescaped '[' token is not allowed inside of a replacement token. Use '[[' to escape."
                 };
 
                 yield return new object[]
                 {
                     "[]",
-                    new { },
+                    new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
                     "An empty replacement token ('[]') is not allowed.",
                 };
             }

test/Microsoft.AspNetCore.Mvc.Core.Test/Infrastructure/DefaultActionSelectorTests.cs

@@ -8,7 +8,6 @@ using System.Reflection;
 using Microsoft.AspNetCore.Http;
 using Microsoft.AspNetCore.Mvc.Abstractions;
 using Microsoft.AspNetCore.Mvc.ActionConstraints;
-using Microsoft.AspNetCore.Mvc.ApplicationModels;
 using Microsoft.AspNetCore.Mvc.ApplicationParts;
 using Microsoft.AspNetCore.Mvc.Controllers;
 using Microsoft.AspNetCore.Mvc.Internal;
@@ -22,10 +21,159 @@ using Xunit;
 
 namespace Microsoft.AspNetCore.Mvc.Infrastructure
 {
+    // Most of the in-depth testing for SelectCandidates is part of the descision tree tests.
+    // This is just basic coverage of the API in common scenarios.
     public class DefaultActionSelectorTests
     {
         [Fact]
-        public void Select_AmbiguousActions_LogIsCorrect()
+        public void SelectCandidates_SingleMatch()
+        {
+            var actions = new ActionDescriptor[]
+            {
+                new ActionDescriptor()
+                {
+                    DisplayName = "A1",
+                    RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
+                },
+                new ActionDescriptor()
+                {
+                    DisplayName = "A2",
+                    RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "About" }
+                    },
+                },
+            };
+
+            var selector = CreateSelector(actions);
+
+            var routeContext = CreateRouteContext("GET");
+            routeContext.RouteData.Values.Add("controller", "Home");
+            routeContext.RouteData.Values.Add("action", "Index");
+
+            // Act
+            var candidates = selector.SelectCandidates(routeContext);
+
+            // Assert
+            Assert.Collection(candidates, (a) => Assert.Same(actions[0], a));
+        }
+
+        [Fact]
+        public void SelectCandidates_MultipleMatches()
+        {
+            var actions = new ActionDescriptor[]
+            {
+                new ActionDescriptor()
+                {
+                    DisplayName = "A1",
+                    RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
+                },
+                new ActionDescriptor()
+                {
+                    DisplayName = "A2",
+                    RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
+                },
+            };
+
+            var selector = CreateSelector(actions);
+
+            var routeContext = CreateRouteContext("GET");
+            routeContext.RouteData.Values.Add("controller", "Home");
+            routeContext.RouteData.Values.Add("action", "Index");
+
+            // Act
+            var candidates = selector.SelectCandidates(routeContext);
+
+            // Assert
+            Assert.Equal(actions.ToArray(), candidates.ToArray());
+        }
+
+        [Fact]
+        public void SelectCandidates_NoMatch()
+        {
+            var actions = new ActionDescriptor[]
+            {
+                new ActionDescriptor()
+                {
+                    DisplayName = "A1",
+                    RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
+                },
+                new ActionDescriptor()
+                {
+                    DisplayName = "A2",
+                    RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "About" }
+                    },
+                },
+            };
+
+            var selector = CreateSelector(actions);
+
+            var routeContext = CreateRouteContext("GET");
+            routeContext.RouteData.Values.Add("controller", "Foo");
+            routeContext.RouteData.Values.Add("action", "Index");
+
+            // Act
+            var candidates = selector.SelectCandidates(routeContext);
+
+            // Assert
+            Assert.Empty(candidates);
+        }
+
+        [Fact]
+        public void SelectCandidates_NoMatch_ExcludesAttributeRoutedActions()
+        {
+            var actions = new ActionDescriptor[]
+            {
+                new ActionDescriptor()
+                {
+                    DisplayName = "A1",
+                    RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                    {
+                        { "controller", "Home" },
+                        { "action", "Index" }
+                    },
+                    AttributeRouteInfo = new AttributeRouteInfo()
+                    {
+                        Template = "/Home",
+                    }
+                },
+            };
+
+            var selector = CreateSelector(actions);
+
+            var routeContext = CreateRouteContext("GET");
+            routeContext.RouteData.Values.Add("controller", "Home");
+            routeContext.RouteData.Values.Add("action", "Index");
+
+            // Act
+            var candidates = selector.SelectCandidates(routeContext);
+
+            // Assert
+            Assert.Empty(candidates);
+        }
+
+        [Fact]
+        public void SelectBestCandidate_AmbiguousActions_LogIsCorrect()
         {
             // Arrange
             var sink = new TestSink();
@@ -44,7 +192,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
                 $"ambiguity. Matching actions: {actionNames}";
 
             // Act
-            Assert.Throws<AmbiguousActionException>(() => { selector.Select(routeContext); });
+            Assert.Throws<AmbiguousActionException>(() => { selector.SelectBestCandidate(routeContext, actions); });
 
             // Assert
             Assert.Empty(sink.Scopes);
@@ -53,7 +201,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
         }
 
         [Fact]
-        public void Select_PrefersActionWithConstraints()
+        public void SelectBestCandidate_PrefersActionWithConstraints()
         {
             // Arrange
             var actionWithConstraints = new ActionDescriptor()
@@ -76,14 +224,14 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             var context = CreateRouteContext("POST");
 
             // Act
-            var action = selector.Select(context);
+            var action = selector.SelectBestCandidate(context, actions);
 
             // Assert
             Assert.Same(action, actionWithConstraints);
         }
 
         [Fact]
-        public void Select_ConstraintsRejectAll()
+        public void SelectBestCandidate_ConstraintsRejectAll()
         {
             // Arrange
             var action1 = new ActionDescriptor()
@@ -108,14 +256,14 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             var context = CreateRouteContext("POST");
 
             // Act
-            var action = selector.Select(context);
+            var action = selector.SelectBestCandidate(context, actions);
 
             // Assert
             Assert.Null(action);
         }
 
         [Fact]
-        public void Select_ConstraintsRejectAll_DifferentStages()
+        public void SelectBestCandidate_ConstraintsRejectAll_DifferentStages()
         {
             // Arrange
             var action1 = new ActionDescriptor()
@@ -142,14 +290,14 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             var context = CreateRouteContext("POST");
 
             // Act
-            var action = selector.Select(context);
+            var action = selector.SelectBestCandidate(context, actions);
 
             // Assert
             Assert.Null(action);
         }
 
         [Fact]
-        public void Select_ActionConstraintFactory()
+        public void SelectBestCandidate_ActionConstraintFactory()
         {
             // Arrange
             var actionWithConstraints = new ActionDescriptor()
@@ -174,14 +322,14 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             var context = CreateRouteContext("POST");
 
             // Act
-            var action = selector.Select(context);
+            var action = selector.SelectBestCandidate(context, actions);
 
             // Assert
             Assert.Same(action, actionWithConstraints);
         }
 
         [Fact]
-        public void Select_ActionConstraintFactory_ReturnsNull()
+        public void SelectBestCandidate_ActionConstraintFactory_ReturnsNull()
         {
             // Arrange
             var nullConstraint = new ActionDescriptor()
@@ -200,7 +348,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             var context = CreateRouteContext("POST");
 
             // Act
-            var action = selector.Select(context);
+            var action = selector.SelectBestCandidate(context, actions);
 
             // Assert
             Assert.Same(action, nullConstraint);
@@ -208,7 +356,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
 
         // There's a custom constraint provider registered that only understands BooleanConstraintMarker
         [Fact]
-        public void Select_CustomProvider()
+        public void SelectBestCandidate_CustomProvider()
         {
             // Arrange
             var actionWithConstraints = new ActionDescriptor()
@@ -230,7 +378,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             var context = CreateRouteContext("POST");
 
             // Act
-            var action = selector.Select(context);
+            var action = selector.SelectBestCandidate(context, actions);
 
             // Assert
             Assert.Same(action, actionWithConstraints);
@@ -238,7 +386,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
 
         // Due to ordering of stages, the first action will be better.
         [Fact]
-        public void Select_ConstraintsInOrder()
+        public void SelectBestCandidate_ConstraintsInOrder()
         {
             // Arrange
             var best = new ActionDescriptor()
@@ -263,7 +411,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             var context = CreateRouteContext("POST");
 
             // Act
-            var action = selector.Select(context);
+            var action = selector.SelectBestCandidate(context, actions);
 
             // Assert
             Assert.Same(action, best);
@@ -271,7 +419,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
 
         // Due to ordering of stages, the first action will be better.
         [Fact]
-        public void Select_ConstraintsInOrder_MultipleStages()
+        public void SelectBestCandidate_ConstraintsInOrder_MultipleStages()
         {
             // Arrange
             var best = new ActionDescriptor()
@@ -300,14 +448,14 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             var context = CreateRouteContext("POST");
 
             // Act
-            var action = selector.Select(context);
+            var action = selector.SelectBestCandidate(context, actions);
 
             // Assert
             Assert.Same(action, best);
         }
 
         [Fact]
-        public void Select_Fallback_ToActionWithoutConstraints()
+        public void SelectBestCandidate_Fallback_ToActionWithoutConstraints()
         {
             // Arrange
             var nomatch1 = new ActionDescriptor()
@@ -338,14 +486,14 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             var context = CreateRouteContext("POST");
 
             // Act
-            var action = selector.Select(context);
+            var action = selector.SelectBestCandidate(context, actions);
 
             // Assert
             Assert.Same(action, best);
         }
 
         [Fact]
-        public void Select_Ambiguous()
+        public void SelectBestCandidate_Ambiguous()
         {
             // Arrange
             var expectedMessage =
@@ -359,7 +507,6 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             {
                 CreateAction(area: null, controller: "Store", action: "Buy"),
                 CreateAction(area: null, controller: "Store", action: "Buy"),
-                CreateAction(area: null, controller: "Store", action: "Cart"),
             };
 
             actions[0].DisplayName = "Ambiguous1";
@@ -374,7 +521,7 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             // Act
             var ex = Assert.Throws<AmbiguousActionException>(() =>
             {
-                selector.Select(context);
+                selector.SelectBestCandidate(context, actions);
             });
 
             // Assert
@@ -528,12 +675,13 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
                 new DefaultActionConstraintProvider(),
             };
 
-            var defaultActionSelector = new ActionSelector(
+            var actionSelector = new ActionSelector(
                 decisionTreeProvider,
                 GetActionConstraintCache(actionConstraintProviders),
                 NullLoggerFactory.Instance);
 
-            return (ControllerActionDescriptor)defaultActionSelector.Select(context);
+            var candidates = actionSelector.SelectCandidates(context);
+            return (ControllerActionDescriptor)actionSelector.SelectBestCandidate(context, candidates);
         }
 
         private ControllerActionDescriptorProvider GetActionDescriptorProvider()

test/Microsoft.AspNetCore.Mvc.Core.Test/Infrastructure/MvcRouteHandlerTests.cs

@@ -2,6 +2,7 @@
 // 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.Diagnostics;
 using System.Threading.Tasks;
 using Microsoft.AspNetCore.Http;
@@ -28,8 +29,8 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
 
             var mockActionSelector = new Mock<IActionSelector>();
             mockActionSelector
-                .Setup(a => a.Select(It.IsAny<RouteContext>()))
+                .Setup(a => a.SelectCandidates(It.IsAny<RouteContext>()))
-                .Returns<ActionDescriptor>(null);
+                .Returns(new ActionDescriptor[0]);
 
             var context = CreateRouteContext();
 
@@ -48,39 +49,6 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             Assert.Equal(expectedMessage, sink.Writes[0].State?.ToString());
         }
 
-        [Fact]
-        public async Task RouteHandler_RemovesRouteGroupFromRouteValues()
-        {
-            // Arrange
-            var invoker = new Mock<IActionInvoker>();
-            invoker
-                .Setup(i => i.InvokeAsync())
-                .Returns(Task.FromResult(true));
-
-            var invokerFactory = new Mock<IActionInvokerFactory>();
-            invokerFactory
-                .Setup(f => f.CreateInvoker(It.IsAny<ActionContext>()))
-                .Returns<ActionContext>((c) =>
-                {
-                    return invoker.Object;
-                });
-
-            var context = CreateRouteContext();
-            var handler = CreateMvcRouteHandler(invokerFactory: invokerFactory.Object);
-
-            var originalRouteData = context.RouteData;
-            originalRouteData.Values.Add(TreeRouter.RouteGroupKey, "/Home/Test");
-
-            // Act
-            await handler.RouteAsync(context);
-
-            // Assert
-            Assert.Same(originalRouteData, context.RouteData);
-
-
-            Assert.False(context.RouteData.Values.ContainsKey(TreeRouter.RouteGroupKey));
-        }
-
         private MvcRouteHandler CreateMvcRouteHandler(
             ActionDescriptor actionDescriptor = null,
             IActionSelector actionSelector = null,
@@ -99,7 +67,12 @@ namespace Microsoft.AspNetCore.Mvc.Infrastructure
             if (actionSelector == null)
             {
                 var mockActionSelector = new Mock<IActionSelector>();
-                mockActionSelector.Setup(a => a.Select(It.IsAny<RouteContext>()))
+                mockActionSelector
+                    .Setup(a => a.SelectCandidates(It.IsAny<RouteContext>()))
+                    .Returns(new ActionDescriptor[] { actionDescriptor });
+
+                mockActionSelector
+                    .Setup(a => a.SelectBestCandidate(It.IsAny<RouteContext>(), It.IsAny<IReadOnlyList<ActionDescriptor>>()))
                     .Returns(actionDescriptor);
                 actionSelector = mockActionSelector.Object;
             }

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/AttributeRouteTest.cs

@@ -32,7 +32,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         public async Task AttributeRoute_UsesUpdatedActionDescriptors()
         {
             // Arrange
-            var handler = CreateHandler();
+            ActionDescriptor selected = null;
 
             var actions = new List<ActionDescriptor>()
             {
@@ -40,28 +40,45 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 {
                     AttributeRouteInfo = new AttributeRouteInfo()
                     {
-                        Template = "api/Blog/{id}"
+                        Template = "api/Blog/{key1}"
-                    },
-                    RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
                     },
                 },
                 new ActionDescriptor()
                 {
                     AttributeRouteInfo = new AttributeRouteInfo()
                     {
-                        Template = "api/Store/Buy/{id}"
+                        Template = "api/Store/Buy/{key2}"
-                    },
-                    RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "2" }
                     },
                 },
             };
 
+
+            Func<ActionDescriptor[], IRouter> handlerFactory = (_) =>
+            {
+                var handler = new Mock<IRouter>();
+                handler
+                    .Setup(r => r.RouteAsync(It.IsAny<RouteContext>()))
+                    .Returns<RouteContext>(routeContext =>
+                    {
+                        if (routeContext.RouteData.Values.ContainsKey("key1"))
+                        {
+                            selected = actions[0];
+                        }
+                        else if (routeContext.RouteData.Values.ContainsKey("key2"))
+                        {
+                            selected = actions[1];
+                        }
+
+                        routeContext.Handler = (c) => TaskCache.CompletedTask;
+
+                        return TaskCache.CompletedTask;
+
+                    });
+                return handler.Object;
+            };
+
             var actionDescriptorProvider = CreateActionDescriptorProvider(actions);
-            var route = CreateRoute(handler.Object, actionDescriptorProvider.Object);
+            var route = CreateRoute(handlerFactory, actionDescriptorProvider.Object);
 
             var requestServices = new Mock<IServiceProvider>(MockBehavior.Strict);
             requestServices
@@ -79,12 +96,11 @@ namespace Microsoft.AspNetCore.Mvc.Internal
 
             // Assert 1
             Assert.NotNull(context.Handler);
-            Assert.Equal("5", context.RouteData.Values["id"]);
+            Assert.Equal("5", context.RouteData.Values["key2"]);
-            Assert.Equal("2", context.RouteData.Values[TreeRouter.RouteGroupKey]);
+            Assert.Same(actions[1], selected);
-
+            
-            handler.Verify(h => h.RouteAsync(It.IsAny<RouteContext>()), Times.Once());
-
             // Arrange 2 - remove the action and update the collection
+            selected = null;
             actions.RemoveAt(1);
             actionDescriptorProvider
                 .SetupGet(ad => ad.ActionDescriptors)
@@ -98,8 +114,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             // Assert 2
             Assert.Null(context.Handler);
             Assert.Empty(context.RouteData.Values);
-
+            Assert.Null(selected);
-            handler.Verify(h => h.RouteAsync(It.IsAny<RouteContext>()), Times.Once());
         }
 
         [Fact]
@@ -117,10 +132,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index" },
@@ -145,7 +156,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     Assert.Equal(RoutePrecedence.ComputeOutbound(e.RouteTemplate), e.Precedence);
                     Assert.Equal("BLOG_INDEX", e.RouteName);
                     Assert.Equal(17, e.Order);
-                    Assert.Equal(actions[0].RouteValueDefaults.ToArray(), e.RequiredLinkValues.ToArray());
+                    Assert.Equal(ToRouteValueDictionary(actions[0].RouteValues), e.RequiredLinkValues);
                     Assert.Equal("api/Blog/{id}", e.RouteTemplate.TemplateText);
                 });
         }
@@ -165,10 +176,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index" },
@@ -193,7 +200,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     Assert.Equal(RoutePrecedence.ComputeOutbound(e.RouteTemplate), e.Precedence);
                     Assert.Equal("BLOG_INDEX", e.RouteName);
                     Assert.Equal(17, e.Order);
-                    Assert.Equal(actions[0].RouteValueDefaults.ToArray(), e.RequiredLinkValues.ToArray());
+                    Assert.Equal(ToRouteValueDictionary(actions[0].RouteValues), e.RequiredLinkValues);
                     Assert.Equal("api/Blog/{id:int}", e.RouteTemplate.TemplateText);
                 });
         }
@@ -213,10 +220,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index" },
@@ -241,7 +244,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     Assert.Equal(RoutePrecedence.ComputeOutbound(e.RouteTemplate), e.Precedence);
                     Assert.Equal("BLOG_INDEX", e.RouteName);
                     Assert.Equal(17, e.Order);
-                    Assert.Equal(actions[0].RouteValueDefaults.ToArray(), e.RequiredLinkValues.ToArray());
+                    Assert.Equal(ToRouteValueDictionary(actions[0].RouteValues), e.RequiredLinkValues);
                     Assert.Equal("api/Blog/{*slug=hello}", e.RouteTemplate.TemplateText);
                 });
         }
@@ -264,10 +267,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index" },
@@ -282,10 +281,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index2" },
@@ -310,7 +305,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     Assert.Equal(RoutePrecedence.ComputeOutbound(e.RouteTemplate), e.Precedence);
                     Assert.Equal("BLOG_INDEX", e.RouteName);
                     Assert.Equal(17, e.Order);
-                    Assert.Equal(actions[0].RouteValueDefaults.ToArray(), e.RequiredLinkValues.ToArray());
+                    Assert.Equal(ToRouteValueDictionary(actions[0].RouteValues), e.RequiredLinkValues);
                     Assert.Equal("api/Blog/{id}", e.RouteTemplate.TemplateText);
                 },
                 e =>
@@ -320,7 +315,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     Assert.Equal(RoutePrecedence.ComputeOutbound(e.RouteTemplate), e.Precedence);
                     Assert.Equal("BLOG_INDEX", e.RouteName);
                     Assert.Equal(17, e.Order);
-                    Assert.Equal(actions[1].RouteValueDefaults.ToArray(), e.RequiredLinkValues.ToArray());
+                    Assert.Equal(ToRouteValueDictionary(actions[1].RouteValues), e.RequiredLinkValues);
                     Assert.Equal("api/Blog/{id}", e.RouteTemplate.TemplateText);
                 });
         }
@@ -340,10 +335,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index" },
@@ -368,9 +359,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     Assert.Equal(RoutePrecedence.ComputeInbound(e.RouteTemplate), e.Precedence);
                     Assert.Equal("BLOG_INDEX", e.RouteName);
                     Assert.Equal("api/Blog/{id}", e.RouteTemplate.TemplateText);
-                    Assert.Collection(
+                    Assert.Empty(e.Defaults);
-                        e.Defaults.OrderBy(kvp => kvp.Key),
-                        kvp => Assert.Equal(new KeyValuePair<string, object>(TreeRouter.RouteGroupKey, "1"), kvp));
                 });
         }
 
@@ -389,10 +378,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index" },
@@ -417,9 +402,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     Assert.Equal(RoutePrecedence.ComputeInbound(e.RouteTemplate), e.Precedence);
                     Assert.Equal("BLOG_INDEX", e.RouteName);
                     Assert.Equal("api/Blog/{id:int}", e.RouteTemplate.TemplateText);
-                    Assert.Collection(
+                    Assert.Empty(e.Defaults);
-                        e.Defaults.OrderBy(kvp => kvp.Key),
-                        kvp => Assert.Equal(new KeyValuePair<string, object>(TreeRouter.RouteGroupKey, "1"), kvp));
                 });
         }
 
@@ -438,10 +421,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index" },
@@ -468,7 +447,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     Assert.Equal("api/Blog/{*slug=hello}", e.RouteTemplate.TemplateText);
                     Assert.Collection(
                         e.Defaults.OrderBy(kvp => kvp.Key),
-                        kvp => Assert.Equal(new KeyValuePair<string, object>(TreeRouter.RouteGroupKey, "1"), kvp),
                         kvp => Assert.Equal(new KeyValuePair<string, object>("slug", "hello"), kvp));
                 });
         }
@@ -491,10 +469,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index" },
@@ -509,10 +483,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                         Order = 17,
                     },
                     RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
-                    {
-                        { TreeRouter.RouteGroupKey, "1" }
-                    },
-                    RouteValueDefaults = new Dictionary<string, object>()
                     {
                         { "controller", "Blog" },
                         { "action", "Index2" },
@@ -537,9 +507,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                     Assert.Equal(RoutePrecedence.ComputeInbound(e.RouteTemplate), e.Precedence);
                     Assert.Equal("BLOG_INDEX", e.RouteName);
                     Assert.Equal("api/Blog/{id}", e.RouteTemplate.TemplateText);
-                    Assert.Collection(
+                    Assert.Empty(e.Defaults);
-                        e.Defaults.OrderBy(kvp => kvp.Key),
-                        kvp => Assert.Equal(new KeyValuePair<string, object>(TreeRouter.RouteGroupKey, "1"), kvp));
                 });
         }
 
@@ -580,6 +548,13 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         private static AttributeRoute CreateRoute(
             IRouter handler, 
             IActionDescriptorCollectionProvider actionDescriptorProvider)
+        {
+            return CreateRoute((_) => handler, actionDescriptorProvider);
+        }
+
+        private static AttributeRoute CreateRoute(
+            Func<ActionDescriptor[], IRouter> handlerFactory,
+            IActionDescriptorCollectionProvider actionDescriptorProvider)
         {
             var services = new ServiceCollection()
                 .AddSingleton<ObjectPoolProvider, DefaultObjectPoolProvider>()
@@ -588,7 +563,20 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 .AddRouting()
                 .AddOptions()
                 .BuildServiceProvider();
-            return new AttributeRoute(handler, actionDescriptorProvider, services);
+            return new AttributeRoute(actionDescriptorProvider, services, handlerFactory);
+        }
+
+        // Needed because new RouteValueDictionary(values) would give us all the properties of
+        // the Dictionary class.
+        private static RouteValueDictionary ToRouteValueDictionary(IDictionary<string, string> values)
+        {
+            var result = new RouteValueDictionary();
+            foreach (var kvp in values)
+            {
+                result.Add(kvp.Key, kvp.Value);
+            }
+
+            return result;
         }
     }
 }

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/AttributeRoutingTest.cs

@@ -14,7 +14,6 @@ using Microsoft.AspNetCore.Mvc.Controllers;
 using Microsoft.AspNetCore.Mvc.Infrastructure;
 using Microsoft.AspNetCore.Mvc.Routing;
 using Microsoft.AspNetCore.Routing;
-using Microsoft.AspNetCore.Routing.Tree;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Logging;
 using Microsoft.Extensions.Logging.Testing;
@@ -43,11 +42,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 "and can occur only at the end of the parameter. The '*' character marks a parameter as catch-all, " +
                 "and can occur only at the start of the parameter." + Environment.NewLine +
                 "Parameter name: routeTemplate";
-
+            
-            var handler = CreateRouter();
             var services = CreateServices(action);
 
-            var route = AttributeRouting.CreateAttributeMegaRoute(handler, services);
+            var route = AttributeRouting.CreateAttributeMegaRoute(services);
 
             // Act & Assert
             var ex = await Assert.ThrowsAsync<InvalidOperationException>(async () =>
@@ -63,7 +61,7 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         {
             // Arrange
             var action = CreateAction("DisallowedParameter", "{foo}/{action}");
-            action.RouteValueDefaults.Add("foo", "bleh");
+            action.RouteValues.Add("foo", "bleh");
 
             var expectedMessage =
                 "The following errors occurred with attribute routing information:" + Environment.NewLine +
@@ -71,11 +69,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 "For action: 'DisallowedParameter'" + Environment.NewLine +
                 "Error: The attribute route '{foo}/{action}' cannot contain a parameter named '{foo}'. " +
                 "Use '[foo]' in the route template to insert the value 'bleh'.";
-
+            
-            var handler = CreateRouter();
             var services = CreateServices(action);
 
-            var route = AttributeRouting.CreateAttributeMegaRoute(handler, services);
+            var route = AttributeRouting.CreateAttributeMegaRoute(services);
 
             // Act & Assert
             var ex = await Assert.ThrowsAsync<InvalidOperationException>(async () =>
@@ -91,10 +88,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
         {
             // Arrange
             var action1 = CreateAction("DisallowedParameter1", "{foo}/{action}");
-            action1.RouteValueDefaults.Add("foo", "bleh");
+            action1.RouteValues.Add("foo", "bleh");
 
             var action2 = CreateAction("DisallowedParameter2", "cool/{action}");
-            action2.RouteValueDefaults.Add("action", "hey");
+            action2.RouteValues.Add("action", "hey");
 
             var expectedMessage =
                 "The following errors occurred with attribute routing information:" + Environment.NewLine +
@@ -106,11 +103,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 "For action: 'DisallowedParameter2'" + Environment.NewLine +
                 "Error: The attribute route 'cool/{action}' cannot contain a parameter named '{action}'. " +
                 "Use '[action]' in the route template to insert the value 'hey'.";
-
+            
-            var handler = CreateRouter();
             var services = CreateServices(action1, action2);
 
-            var route = AttributeRouting.CreateAttributeMegaRoute(handler, services);
+            var route = AttributeRouting.CreateAttributeMegaRoute(services);
 
             // Act & Assert
             var ex = await Assert.ThrowsAsync<InvalidOperationException>(async () =>
@@ -133,14 +129,12 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             action.MethodInfo = actionMethod;
             action.RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
             {
-                { TreeRouter.RouteGroupKey, "group" }
+                { "controller", "Home" },
+                { "action", "Index" },
             };
             action.AttributeRouteInfo = new AttributeRouteInfo();
             action.AttributeRouteInfo.Template = "{controller}/{action}";
 
-            action.RouteValueDefaults.Add("controller", "Home");
-            action.RouteValueDefaults.Add("action", "Index");
-
             var expectedMessage =
                 "The following errors occurred with attribute routing information:" + Environment.NewLine +
                 Environment.NewLine +
@@ -148,10 +142,9 @@ namespace Microsoft.AspNetCore.Mvc.Internal
                 "Error: The attribute route '{controller}/{action}' cannot contain a parameter named '{controller}'. " +
                 "Use '[controller]' in the route template to insert the value 'Home'.";
 
-            var handler = CreateRouter();
             var services = CreateServices(action);
 
-            var route = AttributeRouting.CreateAttributeMegaRoute(handler, services);
+            var route = AttributeRouting.CreateAttributeMegaRoute(services);
 
             // Act & Assert
             var ex = await Assert.ThrowsAsync<InvalidOperationException>(async () =>
@@ -167,19 +160,11 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             return new DisplayNameActionDescriptor()
             {
                 DisplayName = displayName,
-                RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase)
+                RouteValues = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase),
-                {
-                    { TreeRouter.RouteGroupKey, "whatever" }
-                },
                 AttributeRouteInfo = new AttributeRouteInfo { Template = template },
             };
         }
 
-        private static IRouter CreateRouter()
-        {
-            return Mock.Of<IRouter>();
-        }
-
         private static IServiceProvider CreateServices(params ActionDescriptor[] actions)
         {
             var collection = new ActionDescriptorCollection(actions, version: 0);

test/Microsoft.AspNetCore.Mvc.Core.Test/Internal/ControllerActionDescriptorProviderTests.cs

@@ -261,12 +261,10 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             // Assert
             var action = Assert.Single(descriptors);
 
-            Assert.Equal(TreeRouter.RouteGroupKey, Assert.Single(action.RouteValues).Key);
+            var controller = Assert.Single(action.RouteValues, kvp => kvp.Key.Equals("controller"));
-
-            var controller = Assert.Single(action.RouteValueDefaults, kvp => kvp.Key.Equals("controller"));
             Assert.Equal("AttributeRouted", controller.Value);
 
-            var actionConstraint = Assert.Single(action.RouteValueDefaults, kvp => kvp.Key.Equals("action"));
+            var actionConstraint = Assert.Single(action.RouteValues, kvp => kvp.Key.Equals("action"));
             Assert.Equal(nameof(AttributeRoutedController.AttributeRoutedAction), actionConstraint.Value);
         }
 
@@ -916,30 +914,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             Assert.Equal(expectedMessage, ex.Message);
         }
 
-        [Fact]
-        public void AttributeRouting_RouteGroupConstraint_IsAddedOnceForNonAttributeRoutes()
-        {
-            // Arrange
-            var provider = GetProvider(
-                typeof(ConventionalAndAttributeRoutedActionsWithAreaController).GetTypeInfo(),
-                typeof(ConstrainedController).GetTypeInfo());
-
-            // Act
-            var actionDescriptors = provider.GetDescriptors();
-
-            // Assert
-            Assert.NotNull(actionDescriptors);
-            Assert.Equal(4, actionDescriptors.Count());
-
-            foreach (var actionDescriptor in actionDescriptors.Where(ad => ad.AttributeRouteInfo == null))
-            {
-                Assert.Equal(6, actionDescriptor.RouteValues.Count);
-                Assert.Single(
-                    actionDescriptor.RouteValues,
-                    kvp => kvp.Key.Equals(TreeRouter.RouteGroupKey) && string.IsNullOrEmpty(kvp.Value));
-            }
-        }
-
         [Fact]
         public void AttributeRouting_AddsDefaultRouteValues_ForAttributeRoutedActions()
         {
@@ -957,27 +931,22 @@ namespace Microsoft.AspNetCore.Mvc.Internal
 
             var indexAction = Assert.Single(actionDescriptors, ad => ad.ActionName.Equals("Index"));
 
-            Assert.Equal(1, indexAction.RouteValues.Count);
+            Assert.Equal(5, indexAction.RouteValues.Count);
 
-            var routeGroup = Assert.Single(indexAction.RouteValues, kvp => kvp.Key.Equals(TreeRouter.RouteGroupKey));
+            var controllerDefault = Assert.Single(indexAction.RouteValues, rd => rd.Key.Equals("controller", StringComparison.OrdinalIgnoreCase));
-            Assert.NotNull(routeGroup.Value);
-
-            Assert.Equal(5, indexAction.RouteValueDefaults.Count);
-
-            var controllerDefault = Assert.Single(indexAction.RouteValueDefaults, rd => rd.Key.Equals("controller", StringComparison.OrdinalIgnoreCase));
             Assert.Equal("ConventionalAndAttributeRoutedActionsWithArea", controllerDefault.Value);
 
-            var actionDefault = Assert.Single(indexAction.RouteValueDefaults, rd => rd.Key.Equals("action", StringComparison.OrdinalIgnoreCase));
+            var actionDefault = Assert.Single(indexAction.RouteValues, rd => rd.Key.Equals("action", StringComparison.OrdinalIgnoreCase));
             Assert.Equal("Index", actionDefault.Value);
 
-            var areaDefault = Assert.Single(indexAction.RouteValueDefaults, rd => rd.Key.Equals("area", StringComparison.OrdinalIgnoreCase));
+            var areaDefault = Assert.Single(indexAction.RouteValues, rd => rd.Key.Equals("area", StringComparison.OrdinalIgnoreCase));
             Assert.Equal("Home", areaDefault.Value);
 
-            var mvRouteValueDefault = Assert.Single(indexAction.RouteValueDefaults, rd => rd.Key.Equals("key", StringComparison.OrdinalIgnoreCase));
+            var mvRouteValueDefault = Assert.Single(indexAction.RouteValues, rd => rd.Key.Equals("key", StringComparison.OrdinalIgnoreCase));
-            Assert.Null(mvRouteValueDefault.Value);
+            Assert.Equal(string.Empty, mvRouteValueDefault.Value);
 
-            var anotherRouteValue = Assert.Single(indexAction.RouteValueDefaults, rd => rd.Key.Equals("second", StringComparison.OrdinalIgnoreCase));
+            var anotherRouteValue = Assert.Single(indexAction.RouteValues, rd => rd.Key.Equals("second", StringComparison.OrdinalIgnoreCase));
-            Assert.Null(anotherRouteValue.Value);
+            Assert.Equal(string.Empty, anotherRouteValue.Value);
         }
 
         [Fact]
@@ -994,29 +963,6 @@ namespace Microsoft.AspNetCore.Mvc.Internal
             Assert.Equal("stub/ThisIsAnAction", action.AttributeRouteInfo.Template);
         }
 
-        // Token replacement happens before we 'group' routes. So two route templates
-        // that are equivalent after token replacement go to the same 'group'.
-        [Fact]
-        public void AttributeRouting_TokenReplacement_BeforeGroupId()
-        {
-            // Arrange
-            var provider = GetProvider(typeof(SameGroupIdController).GetTypeInfo());
-
-            // Act
-            var actions = provider.GetDescriptors().ToArray();
-
-            var groupIds = actions.Select(
-                a => a.RouteValues
-                    .Where(kvp => kvp.Key == TreeRouter.RouteGroupKey)
-                    .Select(kvp => kvp.Value)
-                    .Single())
-                .ToArray();
-
-            // Assert
-            Assert.Equal(2, groupIds.Length);
-            Assert.Equal(groupIds[0], groupIds[1]);
-        }
-
         // Parameters are validated later. This action uses the forbidden {action} and {controller}
         [Fact]
         public void AttributeRouting_DoesNotValidateParameters()

test/Microsoft.AspNetCore.Mvc.FunctionalTests/RouteDataTest.cs

@@ -59,7 +59,7 @@ namespace Microsoft.AspNetCore.Mvc.FunctionalTests
                 {
                     typeof(RouteCollection).FullName,
                     typeof(AttributeRoute).FullName,
-                    typeof(MvcRouteHandler).FullName,
+                    typeof(MvcAttributeRouteHandler).FullName,
                 },
                 result.Routers);
         }

test/Microsoft.AspNetCore.Mvc.Razor.Test/RazorViewEngineTest.cs

@@ -1148,12 +1148,8 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             Assert.Equal(expected, result.SearchedLocations);
         }
 
-        [Theory]
+        [Fact]
-        // Looks in RouteValueDefaults
+        public void FindPage_SelectsActionCaseInsensitively()
-        [InlineData(true)]
-        // Looks in RouteValues
-        [InlineData(false)]
-        public void FindPage_SelectsActionCaseInsensitively(bool isAttributeRouted)
         {
             // The ActionDescriptor contains "Foo" and the RouteData contains "foo"
             // which matches the case of the constructor thus searching in the appropriate location.
@@ -1177,8 +1173,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
 
             var context = GetActionContextWithActionDescriptor(
                 routeValues,
-                routesInActionDescriptor,
+                routesInActionDescriptor);
-                isAttributeRouted);
 
             // Act
             var result = viewEngine.FindPage(context, "details");
@@ -1190,12 +1185,8 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             pageFactory.Verify();
         }
 
-        [Theory]
+        [Fact]
-        // Looks in RouteValueDefaults
+        public void FindPage_LooksForPages_UsingActionDescriptor_Controller()
-        [InlineData(true)]
-        // Looks in RouteValues
-        [InlineData(false)]
-        public void FindPage_LooksForPages_UsingActionDescriptor_Controller(bool isAttributeRouted)
         {
             // Arrange
             var expected = new[]
@@ -1216,8 +1207,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var viewEngine = CreateViewEngine();
             var context = GetActionContextWithActionDescriptor(
                 routeValues,
-                routesInActionDescriptor,
+                routesInActionDescriptor);
-                isAttributeRouted);
 
             // Act
             var result = viewEngine.FindPage(context, "foo");
@@ -1228,12 +1218,8 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             Assert.Equal(expected, result.SearchedLocations);
         }
 
-        [Theory]
+        [Fact]
-        // Looks in RouteValueDefaults
+        public void FindPage_LooksForPages_UsingActionDescriptor_Areas()
-        [InlineData(true)]
-        // Looks in RouteValues
-        [InlineData(false)]
-        public void FindPage_LooksForPages_UsingActionDescriptor_Areas(bool isAttributeRouted)
         {
             // Arrange
             var expected = new[]
@@ -1257,8 +1243,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var viewEngine = CreateViewEngine();
             var context = GetActionContextWithActionDescriptor(
                 routeValues,
-                routesInActionDescriptor,
+                routesInActionDescriptor);
-                isAttributeRouted);
 
             // Act
             var result = viewEngine.FindPage(context, "foo");
@@ -1269,10 +1254,8 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             Assert.Equal(expected, result.SearchedLocations);
         }
 
-        [Theory]
+        [Fact]
-        [InlineData(true)]
+        public void FindPage_LooksForPages_UsesRouteValuesAsFallback()
-        [InlineData(false)]
-        public void FindPage_LooksForPages_UsesRouteValuesAsFallback(bool isAttributeRouted)
         {
             // Arrange
             var expected = new[]
@@ -1289,8 +1272,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             var viewEngine = CreateViewEngine();
             var context = GetActionContextWithActionDescriptor(
                 routeValues,
-                new Dictionary<string, string>(),
+                new Dictionary<string, string>());
-                isAttributeRouted);
 
             // Act
             var result = viewEngine.FindPage(context, "bar");
@@ -1462,7 +1444,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
         }
 
         [Fact]
-        public void GetNormalizedRouteValue_ReturnsValueFromRouteValues_IfKeyHandlingIsRequired()
+        public void GetNormalizedRouteValue_ReturnsValueFromRouteValues()
         {
             // Arrange
             var key = "some-key";
@@ -1530,112 +1512,6 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             Assert.Equal("route-value", result);
         }
 
-        [Fact]
-        public void GetNormalizedRouteValue_UsesRouteValueDefaults_IfAttributeRouted()
-        {
-            // Arrange
-            var key = "some-key";
-            var actionDescriptor = new ActionDescriptor
-            {
-                AttributeRouteInfo = new AttributeRouteInfo(),
-            };
-            actionDescriptor.RouteValueDefaults[key] = "Route-Value";
-
-            var actionContext = new ActionContext
-            {
-                ActionDescriptor = actionDescriptor,
-                RouteData = new RouteData()
-            };
-
-            actionContext.RouteData.Values[key] = "route-value";
-
-            // Act
-            var result = RazorViewEngine.GetNormalizedRouteValue(actionContext, key);
-
-            // Assert
-            Assert.Equal("Route-Value", result);
-        }
-
-        [Fact]
-        public void GetNormalizedRouteValue_UsesRouteValue_IfRouteValueDefaultsDoesNotMatchRouteValue()
-        {
-            // Arrange
-            var key = "some-key";
-            var actionDescriptor = new ActionDescriptor
-            {
-                AttributeRouteInfo = new AttributeRouteInfo(),
-            };
-            actionDescriptor.RouteValueDefaults[key] = "different-value";
-
-            var actionContext = new ActionContext
-            {
-                ActionDescriptor = actionDescriptor,
-                RouteData = new RouteData()
-            };
-
-            actionContext.RouteData.Values[key] = "route-value";
-
-            // Act
-            var result = RazorViewEngine.GetNormalizedRouteValue(actionContext, key);
-
-            // Assert
-            Assert.Equal("route-value", result);
-        }
-
-        [Fact]
-        public void GetNormalizedRouteValue_ConvertsRouteDefaultToStringValue_IfAttributeRouted()
-        {
-            using (new CultureReplacer())
-            {
-                // Arrange
-                var key = "some-key";
-                var actionDescriptor = new ActionDescriptor
-                {
-                    AttributeRouteInfo = new AttributeRouteInfo(),
-                };
-                actionDescriptor.RouteValueDefaults[key] = 32;
-
-                var actionContext = new ActionContext
-                {
-                    ActionDescriptor = actionDescriptor,
-                    RouteData = new RouteData()
-                };
-
-                actionContext.RouteData.Values[key] = 32;
-
-                // Act
-                var result = RazorViewEngine.GetNormalizedRouteValue(actionContext, key);
-
-                // Assert
-                Assert.Equal("32", result);
-            }
-        }
-
-        [Fact]
-        public void GetNormalizedRouteValue_UsesRouteDataValue_IfKeyDoesNotExistInRouteDefaultValues()
-        {
-            // Arrange
-            var key = "some-key";
-            var actionDescriptor = new ActionDescriptor
-            {
-                AttributeRouteInfo = new AttributeRouteInfo(),
-            };
-
-            var actionContext = new ActionContext
-            {
-                ActionDescriptor = actionDescriptor,
-                RouteData = new RouteData()
-            };
-
-            actionContext.RouteData.Values[key] = "route-value";
-
-            // Act
-            var result = RazorViewEngine.GetNormalizedRouteValue(actionContext, key);
-
-            // Assert
-            Assert.Equal("route-value", result);
-        }
-
         [Fact]
         public void GetNormalizedRouteValue_ConvertsRouteValueToString()
         {
@@ -1743,8 +1619,7 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
 
         private static ActionContext GetActionContextWithActionDescriptor(
             IDictionary<string, object> routeValues,
-            IDictionary<string, string> actionRouteValues,
+            IDictionary<string, string> actionRouteValues)
-            bool isAttributeRouted)
         {
             var httpContext = new DefaultHttpContext();
             var routeData = new RouteData();
@@ -1754,20 +1629,10 @@ namespace Microsoft.AspNetCore.Mvc.Razor.Test
             }
 
             var actionDescriptor = new ActionDescriptor();
-            if (isAttributeRouted)
+
+            foreach (var kvp in actionRouteValues)
             {
-                actionDescriptor.AttributeRouteInfo = new AttributeRouteInfo();
+                actionDescriptor.RouteValues.Add(kvp.Key, kvp.Value);
-                foreach (var kvp in actionRouteValues)
-                {
-                    actionDescriptor.RouteValueDefaults.Add(kvp.Key, kvp.Value);
-                }
-            }
-            else
-            {
-                foreach (var kvp in actionRouteValues)
-                {
-                    actionDescriptor.RouteValues.Add(kvp.Key, kvp.Value);
-                }
             }
 
             return new ActionContext(httpContext, routeData, actionDescriptor);

test/WebSites/BasicWebSite/Areas/Area1/Views/RemoteAttribute_Home/Create.cshtml

@@ -1,9 +1,9 @@
 @model BasicWebSite.Models.RemoteAttributeUser
 @{
     Layout = "_Layout.cshtml";
-    object areaObject;
+    object areaName;
-    ViewContext.ActionDescriptor.RouteValueDefaults.TryGetValue("area", out areaObject);
+    ViewContext.RouteData.Values.TryGetValue("area", out areaName);
-    var areaName = (areaObject as string) ?? "root";
+    areaName = areaName ?? "root";
     ViewBag.Title = "Create in " + areaName + " area.";
 }
 

test/WebSites/BasicWebSite/Areas/Area1/Views/RemoteAttribute_Home/Details.cshtml

@@ -1,9 +1,9 @@
 @model BasicWebSite.Models.RemoteAttributeUser
 @{
     Layout = "_Layout.cshtml";
-    object areaObject;
+    object areaName;
-    ViewContext.ActionDescriptor.RouteValueDefaults.TryGetValue("area", out areaObject);
+    ViewContext.RouteData.Values.TryGetValue("area", out areaName);
-    var areaName = (areaObject as string) ?? "root";
+    areaName = areaName ?? "root";
     ViewBag.Title = "Details in " + areaName + " area.";
 }
 

test/WebSites/BasicWebSite/Views/RemoteAttribute_Home/Create.cshtml

@@ -1,9 +1,9 @@
 @model BasicWebSite.Models.RemoteAttributeUser
 @{
     Layout = "_Layout.cshtml";
-    object areaObject;
+    object areaName;
-    ViewContext.ActionDescriptor.RouteValueDefaults.TryGetValue("area", out areaObject);
+    ViewContext.RouteData.Values.TryGetValue("area", out areaName);
-    var areaName = (areaObject as string) ?? "root";
+    areaName = areaName ?? "root";
     ViewBag.Title = "Create in " + areaName + " area.";
 }
 

test/WebSites/BasicWebSite/Views/RemoteAttribute_Home/Details.cshtml

@@ -1,9 +1,9 @@
 @model BasicWebSite.Models.RemoteAttributeUser
 @{
     Layout = "_Layout.cshtml";
-    object areaObject;
+    string areaName;
-    ViewContext.ActionDescriptor.RouteValueDefaults.TryGetValue("area", out areaObject);
+    ViewContext.RouteData.Values.TryGetValue("area", out areaName);
-    var areaName = (areaObject as string) ?? "root";
+    areaName = areaName ?? "root";
     ViewBag.Title = "Details in " + areaName + " area.";
 }