Remove respond_to/respond_with placeholder methods

This functionality has been extracted to the responders gem.

actionpack/CHANGELOG.md

+*   Remove `respond_to`/`respond_with` placeholder methods, this functionality
+    has been extracted to the `responders` gem.
+
+    *Carlos Antonio da Silva*
+
 *   Remove deprecated assertion files.
 
     *Rafael Mendonça França*

actionpack/lib/action_controller/metal/mime_responds.rb

@@ -3,26 +3,6 @@
 
 module ActionController #:nodoc:
   module MimeResponds
-    extend ActiveSupport::Concern
-
-    module ClassMethods
-      def respond_to(*)
-        raise NoMethodError, "The controller-level `respond_to' feature has " \
-          "been extracted to the `responders` gem. Add it to your Gemfile to " \
-          "continue using this feature:\n" \
-          "  gem 'responders', '~> 2.0'\n" \
-          "Consult the Rails upgrade guide for details."
-      end
-    end
-
-    def respond_with(*)
-      raise NoMethodError, "The `respond_with' feature has been extracted " \
-        "to the `responders` gem. Add it to your Gemfile to continue using " \
-        "this feature:\n" \
-        "  gem 'responders', '~> 2.0'\n" \
-        "Consult the Rails upgrade guide for details."
-    end
-
     # Without web-service support, an action which collects the data for displaying a list of people
     # might look something like this:
     #

actionpack/test/controller/mime/responders_test.rb

-require 'abstract_unit'
-require 'controller/fake_models'
-
-class ResponderTest < ActionController::TestCase
-  def test_class_level_respond_to
-    e = assert_raises(NoMethodError) do
-      Class.new(ActionController::Base) do
-        respond_to :json
-      end
-    end
-
-    assert_includes e.message, '`responders` gem'
-    assert_includes e.message, '~> 2.0'
-  end
-
-  def test_respond_with
-    klass = Class.new(ActionController::Base) do
-      def index
-        respond_with Customer.new("david", 13)
-      end
-    end
-
-    @controller = klass.new
-
-    e = assert_raises(NoMethodError) do
-      get :index
-    end
-
-    assert_includes e.message, '`responders` gem'
-    assert_includes e.message, '~> 2.0'
-  end
-end