Add helper for loading seed data for engine and application

Signed-off-by: José Valim <jose.valim@gmail.com>

activerecord/lib/active_record/railties/databases.rake

@@ -299,8 +299,7 @@ namespace :db do
 
   desc 'Load the seed data from db/seeds.rb'
   task :seed => 'db:abort_if_pending_migrations' do
-    seed_file = File.join(Rails.root, 'db', 'seeds.rb')
+    Rails.application.load_seed
-    load(seed_file) if File.exist?(seed_file)
   end
 
   namespace :fixtures do

railties/lib/rails/engine.rb

@@ -380,6 +380,15 @@ module Rails
       @config ||= Engine::Configuration.new(find_root_with_flag("lib"))
     end
 
+    # Load data from db/seeds.rb file. It can be used in to load engines'
+    # seeds, e.g.:
+    #
+    # Blog::Engine.load_seed
+    def load_seed
+      seed_file = config.paths.db.seeds.to_a.first
+      load(seed_file) if File.exist?(seed_file)
+    end
+
     # Add configured load paths to ruby load paths and remove duplicates.
     initializer :set_load_path, :before => :bootstrap_hook do
       _all_load_paths.reverse_each do |path|

railties/lib/rails/engine/configuration.rb

@@ -37,6 +37,7 @@ module Rails
           paths.vendor.plugins      "vendor/plugins"
           paths.db                  "db"
           paths.db.migrate          "db/migrate"
+          paths.db.seeds            "db/seeds.rb"
           paths
         end
       end

railties/test/railties/engine_test.rb

@@ -624,5 +624,24 @@ module RailtiesTest
         assert !File.exist?(File.join(app_path, 'public/bukkits'))
       end
     end
+
+    test "loading seed data" do
+      @plugin.write "db/seeds.rb", <<-RUBY
+        Bukkits::Engine.config.bukkits_seeds_loaded = true
+      RUBY
+
+      app_file "db/seeds.rb", <<-RUBY
+        Rails.application.config.app_seeds_loaded = true
+      RUBY
+
+      boot_rails
+
+      Rails.application.load_seed
+      assert Rails.application.config.app_seeds_loaded
+      assert_raise(NoMethodError) do  Bukkits::Engine.config.bukkits_seeds_loaded end
+
+      Bukkits::Engine.load_seed
+      assert Bukkits::Engine.config.bukkits_seeds_loaded
+    end
   end
 end