Addressed code review comments.

Author: NTaylorMullen

src/Microsoft.AspNet.Mvc.TagHelpers/FormTagHelper.cs

@@ -5,6 +5,7 @@
 using System.Collections.Generic;
 using System.Linq;
 using Microsoft.AspNet.Mvc.Rendering;
+using Microsoft.AspNet.Mvc.TagHelpers.Internal;
 using Microsoft.AspNet.Razor.Runtime.TagHelpers;
 using Microsoft.AspNet.Razor.TagHelpers;
 
@@ -16,11 +17,10 @@ namespace Microsoft.AspNet.Mvc.TagHelpers
     [ContentBehavior(ContentBehavior.Append)]
     public class FormTagHelper : TagHelper
     {
-        [Activate]
-        private ViewContext ViewContext { get; set; }
+        private const string RouteAttributePrefix = "route-";
 
         [Activate]
-        private AntiForgery AntiForgery { get; set; }
+        private ViewContext ViewContext { get; set; }
 
         [Activate]
         private IHtmlGenerator Generator { get; set; }
@@ -54,72 +54,68 @@ public override void Process(TagHelperContext context, TagHelperOutput output)
             }
             else
             {
-                // TODO: Make this behavior optional once https://github.com/aspnet/Razor/issues/121 is completed.
-                output.Content = AntiForgery.GetHtml(ViewContext.HttpContext).ToString();
-
                 var routeValues = PullRouteValues(output.Attributes);
                 var tagBuilder = Generator.GenerateForm(ViewContext,
                                                         Action,
                                                         Controller,
                                                         routeValues,
                                                         Method,
-                                                        htmlAttributes: new Dictionary<string, object>());
+                                                        htmlAttributes: null);
+
+                TagHelperOutputHelper.Merge(tagBuilder, output);
 
-                TagHelperOutputHelper.MergeAttributes(output, tagBuilder);
+                // TODO: Make this behavior optional once https://github.com/aspnet/Razor/issues/121 is completed.
+                var antiForgeryTag = Generator.GenerateAntiForgery(ViewContext);
+                output.Content += antiForgeryTag.ToString(TagRenderMode.SelfClosing);
             }
         }
 
         // TODO: We will not need this method once https://github.com/aspnet/Razor/issues/89 is completed.
         private static Dictionary<string, object> PullRouteValues(IDictionary<string, string> htmlAttributes)
         {
-            var routeAttributePrefix = "route-";
-
             // We're only interested in HTML attributes that have the desired routeAttributePrefix.
             var routeAttributes = htmlAttributes.Where(attribute =>
-                attribute.Key.StartsWith(routeAttributePrefix, StringComparison.OrdinalIgnoreCase));
+                attribute.Key.StartsWith(RouteAttributePrefix, StringComparison.OrdinalIgnoreCase));
 
-            // We need to remove any route based HTML attributes from the HTML attributes dictionary because
-            // they shouldn't be treated as HTML attributes, they're route values.
+            // Route based HTML attributes shouldn't be treated as HTML attributes, they're only route values.
             foreach (var attribute in routeAttributes)
             {
                 htmlAttributes.Remove(attribute.Key);
             }
 
-            // We build a Dictionary<string, object> because Generator.GenerateForm does not accept a 
-            // Dictionary <string, string>.
-            return routeAttributes.ToDictionary(attribute => attribute.Key.Substring(routeAttributePrefix.Length),
+            // Generator.GenerateForm does not accept a Dictionary<string, string> for routeValues.
+            return routeAttributes.ToDictionary(attribute => attribute.Key.Substring(RouteAttributePrefix.Length),
                                                 attribute => (object)attribute.Value);
         }
 
         private void RestoreBoundHtmlAttributes(TagHelperContext context, TagHelperOutput output)
         {
-            var attributesToRestore = new List<string>();
-
             if (Action != null)
             {
-                attributesToRestore.Add(nameof(Action));
+                RestoreBoundHtmlAttribute(nameof(Action), context, output);
             }
 
             if (Controller != null)
             {
-                attributesToRestore.Add(nameof(Controller));
+                RestoreBoundHtmlAttribute(nameof(Controller), context, output);
             }
 
             if (Method != null)
             {
-                attributesToRestore.Add(nameof(Method));
+                RestoreBoundHtmlAttribute(nameof(Method), context, output);
             }
+        }
 
-            foreach (var attributeName in attributesToRestore)
-            {
-                // We need to look for the KeyValuePair<string, object> attribute so we can ensure that the attribute
-                // that we re-add to the output object has the same attribute name as the one the user typed.
-                var entry = context.AllAttributes.Single(attribute =>
-                    attribute.Key.Equals(attributeName, StringComparison.OrdinalIgnoreCase));
-                var originalAttribute = new KeyValuePair<string, string>(entry.Key, entry.Value.ToString());
+        private static void RestoreBoundHtmlAttribute(string boundAttributeName, 
+                                                      TagHelperContext context, 
+                                                      TagHelperOutput output)
+        {
+            // We look for the original attribute so we can then retrieve the exact attribute name the user typed.
+            var entry = context.AllAttributes.Single(attribute =>
+                attribute.Key.Equals(boundAttributeName, StringComparison.OrdinalIgnoreCase));
+            var originalAttribute = new KeyValuePair<string, string>(entry.Key, entry.Value.ToString());
 
-                output.Attributes.Add(originalAttribute);
-            }
+            output.Attributes.Add(originalAttribute);
         }
     }
 }