Use lazy load hooks to set parameter wrapping configuration. This means that...

Use lazy load hooks to set parameter wrapping configuration. This means that it doesn't force Action Controller / Active Record to load, but it doesn't fail if they have already loaded. Thanks @josevalim for the hint.

actionpack/lib/action_controller/metal/params_wrapper.rb

@@ -121,8 +121,6 @@ def wrap_parameters(name_or_model_or_options, options = {})
         _set_wrapper_defaults(_wrapper_options.slice(:format).merge(options), model)
       end
 
-      alias :wrap_parameters= :wrap_parameters
-
       # Sets the default wrapper key or model which will be used to determine
       # wrapper key and attribute names. Will be called automatically when the
       # module is inherited.

actionpack/test/controller/params_wrapper_test.rb

@@ -180,13 +180,6 @@ def test_not_wrapping_abstract_model
       assert_parameters({ 'username' => 'sikachu', 'title' => 'Developer', 'user' => { 'username' => 'sikachu', 'title' => 'Developer' }})
     end
   end
-
-  def test_assignment_alias
-    with_default_wrapper_options do
-      UsersController.wrap_parameters = { :format => [:foo] }
-      assert_equal({ :format => [:foo], :name => "user" }, UsersController._wrapper_options)
-    end
-  end
 end
 
 class NamespacedParamsWrapperTest < ActionController::TestCase

railties/lib/rails/generators/rails/app/templates/config/initializers/wrap_parameters.rb.tt

@@ -3,12 +3,14 @@
 # This file contains settings for ActionController::ParamsWrapper which
 # is enabled by default.
 
-<%= app_const %>.configure do
-  # Enable parameter wrapping for JSON. You can disable this by setting :format to an empty array.
-  config.action_controller.wrap_parameters = { <%= key_value :format, "[:json]" %> }
+# Enable parameter wrapping for JSON. You can disable this by setting :format to an empty array.
+ActiveSupport.on_load(:action_controller) do
+  wrap_parameters <%= key_value :format, "[:json]" %>
+end
 
-  <%- unless options.skip_active_record? -%>
-  # Disable root element in JSON by default.
-  config.active_record.include_root_in_json = false
-  <%- end -%>
+<%- unless options.skip_active_record? -%>
+# Disable root element in JSON by default.
+ActiveSupport.on_load(:active_record) do
+  self.include_root_in_json = false
 end
+<%- end -%>