Use ActiveSupport.on_load to hook into Active Record and Mongoid.

CHANGELOG.md

@@ -12,6 +12,8 @@
   * Remove the `Devise::Models::Recoverable#after_password_reset` method.
 * bug fixes
   * Fix an `ActionDispatch::IllegalStateError` when testing controllers with Rails 5 rc 2(by @hamadata).
+  * Use `ActiveSupport.on_load` hooks to include Devise on `ActiveRecord` and `Mongoid`,
+    avoiding autoloading these constants too soon (by @lucasmazza, @rafaelfranca).
 * enhancements
   * Display the minimum password length on `registrations/edit` view (by @Yanchek99).
   * You can disable Devise's routes reloading on boot by through the `reload_routes = false` config.

lib/devise/orm/active_record.rb

@@ -1,3 +1,5 @@
 require 'orm_adapter/adapters/active_record'
 
-ActiveRecord::Base.extend Devise::Models
+ActiveSupport.on_load(:active_record) do
+  extend Devise::Models
+end

lib/devise/orm/mongoid.rb

@@ -1,3 +1,5 @@
-require 'orm_adapter/adapters/mongoid'
+ActiveSupport.on_load(:mongoid) do
+  require 'orm_adapter/adapters/mongoid'
 
-Mongoid::Document::ClassMethods.send :include, Devise::Models
+  Mongoid::Document::ClassMethods.send :include, Devise::Models
+end