Add deprecation for the change to the active_record load hook

2 files changed, 38 insertions, 1 deletions

diff --git a/activerecord/lib/active_record/model.rb b/activerecord/lib/active_record/model.rb
index 4e8ed14fb7..025f40359a 100644
--- a/activerecord/lib/active_record/model.rb
+++ b/activerecord/lib/active_record/model.rb
@@ -1,3 +1,5 @@
+require 'active_support/deprecation'
+
 module ActiveRecord
   module Model
     # So we can recognise an AR class even while self.included is being
@@ -50,8 +52,29 @@ module ActiveRecord
         self.connection_handler = Base.connection_handler
       end
     end
+
+    module DeprecationProxy #:nodoc:
+      class << self
+        instance_methods.each { |m| undef_method m unless m =~ /^__|^object_id$|^instance_eval$/ }
+
+        def method_missing(name, *args, &block)
+          if Model.respond_to?(name)
+            Model.send(name, *args, &block)
+          else
+            ActiveSupport::Deprecation.warn(
+              "The object passed to the active_record load hook was previously ActiveRecord::Base " \
+              "(a Class). Now it is ActiveRecord::Model (a Module). You have called `#{name}' which " \
+              "is only defined on ActiveRecord::Base. Please change your code so that it works with " \
+              "a module rather than a class. (Model is included in Base, so anything added to Model " \
+              "will be available on Base as well.)"
+            )
+            Base.send(name, *args, &block)
+          end
+        end
+      end
+    end
   end
 end
 
 require 'active_record/connection_adapters/abstract/connection_specification'
-ActiveSupport.run_load_hooks(:active_record, ActiveRecord::Model)
+ActiveSupport.run_load_hooks(:active_record, ActiveRecord::Model::DeprecationProxy)
diff --git a/activerecord/test/cases/inclusion_test.rb b/activerecord/test/cases/inclusion_test.rb
index 4b3320cf04..374e4e01d3 100644
--- a/activerecord/test/cases/inclusion_test.rb
+++ b/activerecord/test/cases/inclusion_test.rb
@@ -74,6 +74,20 @@ class InclusionUnitTest < ActiveRecord::TestCase
   def test_included_twice
     @klass.send :include, ActiveRecord::Model
   end
+
+  def test_deprecation_proxy
+    assert_equal ActiveRecord::Model.name, ActiveRecord::Model::DeprecationProxy.name
+    assert_equal ActiveRecord::Base.superclass, assert_deprecated { ActiveRecord::Model::DeprecationProxy.superclass }
+
+    sup = nil
+    ActiveSupport.on_load(:__test_active_record_model_deprecation) do
+      sup = superclass
+    end
+    assert_deprecated do
+      ActiveSupport.run_load_hooks(:__test_active_record_model_deprecation, ActiveRecord::Model::DeprecationProxy)
+    end
+    assert_equal ActiveRecord::Base.superclass, sup
+  end
 end
 
 class InclusionFixturesTest < ActiveRecord::TestCase