Don't include the same module several times, closes #765.

lib/devise/models.rb

@@ -51,12 +51,12 @@ module Devise
       include Devise::Models::Authenticatable
       options = modules.extract_options!.dup
 
-      self.devise_modules += modules.map(&:to_sym).uniq.sort_by { |s|
+      selected_modules = modules.map(&:to_sym).uniq.sort_by do |s|
         Devise::ALL.index(s) || -1  # follow Devise::ALL order
-      }
+      end
 
       devise_modules_hook! do
-        devise_modules.each do |m|
+        selected_modules.each do |m|
           mod = Devise::Models.const_get(m.to_s.classify)
 
           if mod.const_defined?("ClassMethods")
@@ -75,6 +75,7 @@ module Devise
           include mod
         end
 
+        self.devise_modules |= selected_modules
         options.each { |key, value| send(:"#{key}=", value) }
       end
     end

test/models_test.rb

@@ -10,6 +10,11 @@ class WithValidation < Admin
   devise :database_authenticatable, :validatable, :password_length => 2..6
 end
 
+class Several < Admin
+  devise :validatable
+  devise :lockable
+end
+
 class Inheritable < Admin
 end
 
@@ -33,11 +38,18 @@ class ActiveRecordTest < ActiveSupport::TestCase
     assert_include_modules Admin, :database_authenticatable, :registerable, :timeoutable, :recoverable, :lockable, :rememberable, :encryptable
   end
 
-  test 'validations options are not applied to late' do
-    validators = WithValidation.validators_on :password
-    length = validators.find { |v| v.kind == :length }
-    assert_equal 2, length.options[:minimum]
-    assert_equal 6, length.options[:maximum]
+  if DEVISE_ORM == :active_record
+    test 'validations options are not applied to late' do
+      validators = WithValidation.validators_on :password
+      length = validators.find { |v| v.kind == :length }
+      assert_equal 2, length.options[:minimum]
+      assert_equal 6, length.options[:maximum]
+    end
+
+    test 'validations are applied just once' do
+      validators = Several.validators_on :password
+      assert_equal 1, validators.select{ |v| v.kind == :length }.length
+    end
   end
 
   test 'chosen modules are inheritable' do