Add command recorder for our migrations

This is for Rails 3.1+

features/migration.feature

@@ -68,3 +68,27 @@ Feature: Migration
 
     When I rollback a migration
     Then I should not have attachment columns for "avatar"
+
+  Scenario: Rails 3.2 change method
+    Given I am using Rails newer than 3.1
+    When I write to "db/migrate/01_create_users.rb" with:
+      """
+      class CreateUsers < ActiveRecord::Migration
+        def self.up
+          create_table :users
+        end
+      end
+      """
+    When I write to "db/migrate/02_add_attachment_to_users.rb" with:
+      """
+      class AddAttachmentToUsers < ActiveRecord::Migration
+        def change
+          add_attachment :users, :avatar
+        end
+      end
+      """
+    And I run a migration
+    Then I should have attachment columns for "avatar"
+
+    When I rollback a migration
+    Then I should not have attachment columns for "avatar"

features/step_definitions/rails_steps.rb

@@ -130,3 +130,9 @@ end
 When /^I comment out the gem "([^"]*)" from the Gemfile$/ do |gemname|
   comment_out_gem_in_gemfile gemname
 end
+
+Given /^I am using Rails newer than ([\d\.]+)$/ do |version|
+  if framework_version < version
+    pending "Not supported in Rails < #{version}"
+  end
+end

lib/paperclip/schema.rb

@@ -12,6 +12,10 @@ module Paperclip
       ActiveRecord::ConnectionAdapters::Table.send :include, TableDefinition
       ActiveRecord::ConnectionAdapters::TableDefinition.send :include, TableDefinition
       ActiveRecord::ConnectionAdapters::AbstractAdapter.send :include, Statements
+
+      if defined?(ActiveRecord::Migration::CommandRecorder) # Rails 3.1+
+        ActiveRecord::Migration::CommandRecorder.send :include, CommandRecorder
+      end
     end
 
     module Statements
@@ -55,5 +59,17 @@ module Paperclip
         attachment(*attachment_names)
       end
     end
+
+    module CommandRecorder
+      def add_attachment(*args)
+        record(:add_attachment, args)
+      end
+
+      private
+
+      def invert_add_attachment(args)
+        [:remove_attachment, args]
+      end
+    end
   end
 end