Add mailers to paths in case someone wants to access it directly and ensures deep nesting works in controllers.

railties/lib/rails/engine.rb

@@ -82,7 +82,7 @@ def load_tasks
     initializer :add_routing_namespaces do |app|
       paths.app.controllers.to_a.each do |load_path|
         load_path = File.expand_path(load_path)
-        Dir["#{load_path}/*/*_controller.rb"].collect do |path|
+        Dir["#{load_path}/*/**/*_controller.rb"].collect do |path|
           namespace = File.dirname(path).sub(/#{load_path}\/?/, '')
           app.routes.controller_namespaces << namespace unless namespace.empty?
         end

railties/lib/rails/engine/configuration.rb

@@ -18,8 +18,9 @@ def paths
           paths.app.controllers     "app/controllers",     :eager_load => true
           paths.app.helpers         "app/helpers",         :eager_load => true
           paths.app.models          "app/models",          :eager_load => true
-          paths.app.metals          "app/metal"
-          paths.app.views           "app/views"
+          paths.app.mailers         "app/mailers",         :eager_load => true
+          paths.app.metals          "app/metal",           :eager_load => true
+          paths.app.views           "app/views",           :eager_load => true
           paths.lib                 "lib",                 :load_path => true
           paths.lib.tasks           "lib/tasks",           :glob => "**/*.rake"
           paths.lib.templates       "lib/templates"

railties/test/application/paths_test.rb

@@ -56,9 +56,10 @@ def assert_not_in_load_path(*path)
     end
 
     test "booting up Rails yields a list of paths that are eager" do
-      assert @paths.app.eager_load?
-      assert @paths.app.controllers.eager_load?
-      assert @paths.app.helpers.eager_load?
+      eager_load = @paths.eager_load
+      assert eager_load.include?(root("app/controllers"))
+      assert eager_load.include?(root("app/helpers"))
+      assert eager_load.include?(root("app/models"))
     end
 
     test "environments has a glob equal to the current environment" do

railties/test/railties/shared_tests.rb

@@ -263,13 +263,15 @@ def test_namespaced_controllers_with_namespaced_routes
       @plugin.write "config/routes.rb", <<-RUBY
         Rails.application.routes.draw do
           namespace :admin do
-            match "index", :to => "admin/foo#index"
+            namespace :foo do
+              match "bar", :to => "admin/foo/bar#index"
+            end
           end
         end
       RUBY
 
-      @plugin.write "app/controllers/admin/foo_controller.rb", <<-RUBY
-        class Admin::FooController < ApplicationController
+      @plugin.write "app/controllers/admin/foo/bar_controller.rb", <<-RUBY
+        class Admin::Foo::BarController < ApplicationController
           def index
             render :text => "Rendered from namespace"
           end
@@ -280,7 +282,7 @@ def index
       require 'rack/test'
       extend Rack::Test::Methods
 
-      get "/admin/index"
+      get "/admin/foo/bar"
       assert_equal 200, last_response.status
       assert_equal "Rendered from namespace", last_response.body
     end