Warn if acts_as_paranoid is called more than once on the same model

which will breaks the method aliasing of `#destroy` and makes them lost
access to the original one defined by ActiveRecord

CHANGELOG.md

@@ -1,5 +1,11 @@
 # paranoia Changelog
 
+## 2.5.2
+
+* [#492](https://github.com/rubysherpas/paranoia/pull/492) Warn if acts_as_paranoid is called more than once on the same model
+
+ [Ignatius Reza](https://github.com/ignatiusreza)
+
 ## 2.5.1
 
 * [#481](https://github.com/rubysherpas/paranoia/pull/481) Replaces hard coded `deleted_at` with `paranoia_column`.

lib/paranoia.rb

@@ -242,6 +242,12 @@ def restore_associated_records(recovery_window_range = nil)
 ActiveSupport.on_load(:active_record) do
   class ActiveRecord::Base
     def self.acts_as_paranoid(options={})
+      if included_modules.include?(Paranoia)
+        puts "[WARN] #{self.name} is calling acts_as_paranoid more than once!"
+
+        return
+      end
+
       define_model_callbacks :restore, :real_destroy
 
       alias_method :really_destroyed?, :destroyed?

test/paranoia_test.rb

@@ -83,6 +83,17 @@ def test_paranoid_model_class_is_paranoid
     assert_equal true, ParanoidModel.paranoid?
   end
 
+  def test_doubly_paranoid_model_class_is_warned
+    assert_output(/DoublyParanoidModel is calling acts_as_paranoid more than once!/) do
+      DoublyParanoidModel.acts_as_paranoid
+    end
+
+    refute_equal(
+      DoublyParanoidModel.instance_method(:destroy).source_location,
+      DoublyParanoidModel.instance_method(:destroy_without_paranoia).source_location
+    )
+  end
+
   def test_plain_models_are_not_paranoid
     assert_equal false, PlainModel.new.paranoid?
   end
@@ -1099,6 +1110,11 @@ class ParanoidModel < ActiveRecord::Base
   acts_as_paranoid
 end
 
+class DoublyParanoidModel < ActiveRecord::Base
+  self.table_name = 'plain_models'
+  acts_as_paranoid
+end
+
 class ParanoidWithUnparanoids < ActiveRecord::Base
   self.table_name = 'plain_models'
   has_many :unparanoid_unique_models