Cache failure_app action builder and pipe call through delegator.

lib/devise.rb

@@ -6,10 +6,11 @@ require 'set'
 require 'securerandom'
 
 module Devise
-  autoload :FailureApp, 'devise/failure_app'
-  autoload :OmniAuth, 'devise/omniauth'
+  autoload :Delegator,   'devise/delegator'
+  autoload :FailureApp,  'devise/failure_app'
+  autoload :OmniAuth,    'devise/omniauth'
   autoload :PathChecker, 'devise/path_checker'
-  autoload :Schema, 'devise/schema'
+  autoload :Schema,      'devise/schema'
   autoload :TestHelpers, 'devise/test_helpers'
 
   module Controllers
@@ -407,7 +408,7 @@ module Devise
   # block.
   def self.configure_warden! #:nodoc:
     @@warden_configured ||= begin
-      warden_config.failure_app   = Devise::FailureApp
+      warden_config.failure_app   = Devise::Delegator.new
       warden_config.default_scope = Devise.default_scope
       warden_config.intercept_401 = false
 

lib/devise/delegator.rb

@@ -0,0 +1,7 @@
+module Devise
+  class Delegator
+    def call(env)
+      Devise::FailureApp.call(env)
+    end
+  end
+end

lib/devise/failure_app.rb

@@ -15,7 +15,8 @@ module Devise
     delegate :flash, :to => :request
 
     def self.call(env)
-      action(:respond).call(env)
+      @respond ||= action(:respond)
+      @respond.call(env)
     end
 
     def self.default_url_options(*args)

test/devise_test.rb

@@ -25,7 +25,7 @@ class DeviseTest < ActiveSupport::TestCase
   end
 
   test 'stores warden configuration' do
-    assert_equal Devise::FailureApp, Devise.warden_config.failure_app
+    assert_kind_of Devise::Delegator, Devise.warden_config.failure_app
     assert_equal :user, Devise.warden_config.default_scope
   end