1 files changed, 25 insertions, 23 deletions
diff --git a/actionpack/lib/action_dispatch/routing/route_set.rb b/actionpack/lib/action_dispatch/routing/route_set.rb
index f3d7a234d7..2fe61c7aa6 100644
--- a/actionpack/lib/action_dispatch/routing/route_set.rb
+++ b/actionpack/lib/action_dispatch/routing/route_set.rb
@@ -21,8 +21,8 @@ module ActionDispatch
       alias inspect to_s
 
       class Dispatcher < Routing::Endpoint
-        def initialize(defaults)
-          @defaults = defaults
+        def initialize(raise_on_name_error)
+          @raise_on_name_error = raise_on_name_error
           @controller_class_names = ThreadSafe::Cache.new
         end
 
@@ -34,12 +34,11 @@ module ActionDispatch
 
           prepare_params!(params)
 
-          # Just raise undefined constant errors if a controller was specified as default.
-          unless controller = controller(params, @defaults.key?(:controller))
+          controller = controller(params, @raise_on_name_error) do
             return [404, {'X-Cascade' => 'pass'}, []]
           end
 
-          dispatch(controller, params[:action], req.env)
+          dispatch(controller, params[:action], req)
         end
 
         def prepare_params!(params)
@@ -53,24 +52,26 @@ module ActionDispatch
         # segment, as in :controller(/:action), we should simply return nil and
         # delegate the control back to Rack cascade. Besides, if this is not a default
         # controller, it means we should respect the @scope[:module] parameter.
-        def controller(params, default_controller=true)
-          if params && params.key?(:controller)
-            controller_param = params[:controller]
-            controller_reference(controller_param)
-          end
+        def controller(params, raise_on_name_error=true)
+          controller_reference params.fetch(:controller) { yield }
         rescue NameError => e
-          raise ActionController::RoutingError, e.message, e.backtrace if default_controller
+          raise ActionController::RoutingError, e.message, e.backtrace if raise_on_name_error
+          yield
         end
 
-      private
+      protected
+
+        attr_reader :controller_class_names
 
         def controller_reference(controller_param)
-          const_name = @controller_class_names[controller_param] ||= "#{controller_param.camelize}Controller"
+          const_name = controller_class_names[controller_param] ||= "#{controller_param.camelize}Controller"
           ActiveSupport::Dependencies.constantize(const_name)
         end
 
-        def dispatch(controller, action, env)
-          controller.action(action).call(env)
+      private
+
+        def dispatch(controller, action, req)
+          controller.action(action).call(req.env)
         end
 
         def normalize_controller!(params)
@@ -267,7 +268,7 @@ module ActionDispatch
                 path_params -= controller_options.keys
                 path_params -= result.keys
               end
-              inner_options.each do |key, _|
+              inner_options.each_key do |key|
                 path_params.delete(key)
               end
 
@@ -313,7 +314,7 @@ module ActionDispatch
 
       attr_accessor :formatter, :set, :named_routes, :default_scope, :router
       attr_accessor :disable_clear_and_finalize, :resources_path_names
-      attr_accessor :default_url_options
+      attr_accessor :default_url_options, :dispatcher_class
       attr_reader :env_key
 
       alias :routes :set
@@ -356,6 +357,7 @@ module ActionDispatch
         @set    = Journey::Routes.new
         @router = Journey::Router.new @set
         @formatter = Journey::Formatter.new @set
+        @dispatcher_class = Routing::RouteSet::Dispatcher
       end
 
       def relative_url_root
@@ -413,8 +415,8 @@ module ActionDispatch
         @prepend.each { |blk| eval_block(blk) }
       end
 
-      def dispatcher(defaults)
-        Routing::RouteSet::Dispatcher.new(defaults)
+      def dispatcher(raise_on_name_error)
+        dispatcher_class.new(raise_on_name_error)
       end
 
       module MountedHelpers
@@ -813,12 +815,12 @@ module ActionDispatch
           if app.matches?(req) && app.dispatcher?
             dispatcher = app.app
 
-            if dispatcher.controller(params, false)
-              dispatcher.prepare_params!(params)
-              return params
-            else
+            dispatcher.controller(params, false) do
               raise ActionController::RoutingError, "A route matches #{path.inspect}, but references missing controller: #{params[:controller].camelize}Controller"
             end
+
+            dispatcher.prepare_params!(params)
+            return params
           end
         end