Routes reloader knows how to reload external files

railties/lib/rails/application/routes_reloader.rb

@@ -3,12 +3,13 @@ require "active_support/core_ext/module/delegation"
 module Rails
   class Application
     class RoutesReloader
-      attr_reader :route_sets, :paths
+      attr_reader :route_sets, :paths, :external_routes
       delegate :execute_if_updated, :execute, :updated?, :to => :updater
 
       def initialize
-        @paths      = []
-        @route_sets = []
+        @paths           = []
+        @route_sets      = []
+        @external_routes = []
       end
 
       def reload!
@@ -23,7 +24,12 @@ module Rails
 
       def updater
         @updater ||= begin
-          updater = ActiveSupport::FileUpdateChecker.new(paths) { reload! }
+          dirs = @external_routes.inject({}) do |hash, dir|
+            hash.merge(dir.to_s => ["rb"])
+          end
+
+          updater = ActiveSupport::FileUpdateChecker.new(paths, dirs) { reload! }
+
           updater.execute
           updater
         end

railties/lib/rails/engine.rb

@@ -546,10 +546,12 @@ module Rails
 
     initializer :add_routing_paths do |app|
       paths = self.paths["config/routes.rb"].existent
+      external_paths = self.paths["config/routes"].paths
 
       if routes? || paths.any?
         app.routes_reloader.paths.unshift(*paths)
         app.routes_reloader.route_sets << routes
+        app.routes_reloader.external_routes.unshift(*external_paths)
       end
     end
 

railties/test/application/routing_test.rb

@@ -190,6 +190,67 @@ module ApplicationTests
       assert_equal 'success!', last_response.body
     end
 
+    {"development" => "baz", "production" => "bar"}.each do |mode, expected|
+      test "reloads routes when external configuration is changed in #{mode}" do
+        controller :foo, <<-RUBY
+          class FooController < ApplicationController
+            def bar
+              render :text => "bar"
+            end
+
+            def baz
+              render :text => "baz"
+            end
+          end
+        RUBY
+
+        app_file 'config/routes.rb', <<-RUBY
+          AppTemplate::Application.routes.draw do
+            draw :external
+          end
+        RUBY
+
+        app_file 'config/routes/external.rb', <<-RUBY
+          get 'foo', :to => 'foo#bar'
+        RUBY
+
+        app(mode)
+
+        get '/foo'
+        assert_equal 'bar', last_response.body
+
+        app_file 'config/routes/external.rb', <<-RUBY
+          get 'foo', :to => 'foo#baz'
+        RUBY
+
+        sleep 0.1
+
+        get '/foo'
+        assert_equal expected, last_response.body
+
+        app_file 'config/routes.rb', <<-RUBY
+          AppTemplate::Application.routes.draw do
+            draw :external
+            draw :other_external
+          end
+        RUBY
+
+        app_file 'config/routes/other_external.rb', <<-RUBY
+          get 'win', :to => 'foo#baz'
+        RUBY
+
+        sleep 0.1
+
+        get '/win'
+
+        if mode == "development"
+          assert_equal expected, last_response.body
+        else
+          assert_equal 404, last_response.status
+        end
+      end
+    end
+
     {"development" => "baz", "production" => "bar"}.each do |mode, expected|
       test "reloads routes when configuration is changed in #{mode}" do
         controller :foo, <<-RUBY