rake db:copy_migrations task, which copies railties migrations into...

rake db:copy_migrations task, which copies railties migrations into application's db/migrate directory

activerecord/lib/active_record/railties/databases.rake

@@ -5,6 +5,28 @@ namespace :db do
     ActiveRecord::Migrator.migrations_path = Rails.application.config.paths.db.migrate.to_a.first
   end
 
+  desc "Copies missing migrations from Railties (e.g. plugins, engines). You can specify Railties to use with FROM=railtie1,railtie2"
+  task :copy_migrations => :load_config do
+    to_load = ENV["FROM"].blank? ? :all : ENV["FROM"].split(",").map {|n| n.strip }
+    railties = {}
+    Rails.application.railties.all do |railtie|
+      next unless to_load == :all || to_load.include?(railtie.railtie_name)
+
+      if railtie.config.respond_to?(:paths) && railtie.config.paths.db
+        railties[railtie.railtie_name] = railtie.config.paths.db.migrate.to_a.first
+      end
+    end
+
+    copied = ActiveRecord::Migration.copy(ActiveRecord::Migrator.migrations_path, railties)
+
+    if copied.blank?
+      puts "No migrations were copied, project is up to date."
+    else
+      puts "The following migrations were copied:"
+      puts copied.map{ |path| File.basename(path) }.join("\n")
+    end
+  end
+
   namespace :create do
     # desc 'Create all the local databases defined in config/database.yml'
     task :all => :load_config do

railties/test/railties/shared_tests.rb

@@ -10,6 +10,55 @@ def app
       @app ||= Rails.application
     end
 
+    def test_copying_migrations
+      @plugin.write "db/migrate/1_create_users.rb", <<-RUBY
+        class CreateUsers < ActiveRecord::Migration
+        end
+      RUBY
+
+      @plugin.write "db/migrate/2_add_last_name_to_users.rb", <<-RUBY
+        class AddLastNameToUsers < ActiveRecord::Migration
+        end
+      RUBY
+
+      app_file "db/migrate/1_create_sessions.rb", <<-RUBY
+        class CreateSessions < ActiveRecord::Migration
+        end
+      RUBY
+
+      yaffle = plugin "acts_as_yaffle", "::LEVEL = config.log_level" do |plugin|
+        plugin.write "lib/acts_as_yaffle.rb", "class ActsAsYaffle; end"
+      end
+
+      yaffle.write "db/migrate/1_create_yaffles.rb", <<-RUBY
+        class CreateYaffles < ActiveRecord::Migration
+        end
+      RUBY
+
+      add_to_config "ActiveRecord::Base.timestamped_migrations = false"
+
+      Dir.chdir(app_path) do
+        output = `rake db:copy_migrations FROM=bukkits`
+
+        assert File.exists?("#{app_path}/db/migrate/2_create_users.bukkits.rb")
+        assert File.exists?("#{app_path}/db/migrate/3_add_last_name_to_users.bukkits.rb")
+        assert_match /2_create_users/, output
+        assert_match /3_add_last_name_to_users/, output
+        assert_equal 3, Dir["#{app_path}/db/migrate/*.rb"].length
+
+        output = `rake db:copy_migrations`
+
+        assert File.exists?("#{app_path}/db/migrate/4_create_yaffles.acts_as_yaffle.rb")
+        assert_match /4_create_yaffles/, output
+
+        migrations_count = Dir["#{app_path}/db/migrate/*.rb"].length
+        output = `rake db:copy_migrations`
+
+        assert_equal migrations_count, Dir["#{app_path}/db/migrate/*.rb"].length
+        assert_match /No migrations were copied/, output
+      end
+    end
+
     def test_puts_its_lib_directory_on_load_path
       boot_rails
       require "another"