Add Rails.groups to encapsulate available groups for require.

2 files changed, 38 insertions, 0 deletions

diff --git a/railties/lib/rails.rb b/railties/lib/rails.rb
index cca0891835..df92934457 100644
--- a/railties/lib/rails.rb
+++ b/railties/lib/rails.rb
@@ -87,6 +87,29 @@ module Rails
       RAILS_CACHE
     end
 
+    # Returns all rails groups for loading based on:
+    #
+    # * The Rails environment;
+    # * The environment variable RAILS_GROUPS;
+    # * The optional hash given as argument with group dependencies;
+    #
+    # == Examples
+    #
+    #   groups :assets => [:development, :test]
+    #
+    #   # Returns
+    #   # => [:default, :development, :assets] for Rails.env == "development"
+    #   # => [:default, :production]           for Rails.env == "production"
+    #
+    def groups(hash={})
+      env = Rails.env
+      groups = [:default, env]
+      groups.concat ENV["RAILS_GROUPS"].to_s.split(",")
+      groups.concat hash.map { |k,v| k if v.map(&:to_s).include?(env) }
+      groups.compact!
+      groups
+    end
+
     def version
       VERSION::STRING
     end
diff --git a/railties/test/application/configuration_test.rb b/railties/test/application/configuration_test.rb
index 477dada820..2547863d12 100644
--- a/railties/test/application/configuration_test.rb
+++ b/railties/test/application/configuration_test.rb
@@ -39,6 +39,21 @@ module ApplicationTests
       FileUtils.rm_rf(new_app) if File.directory?(new_app)
     end
 
+    test "Rails.groups returns available groups" do
+      require "rails"
+
+      Rails.env = "development"
+      assert_equal [:default, "development"], Rails.groups
+      assert_equal [:default, "development", :assets], Rails.groups(:assets => [:development])
+      assert_equal [:default, "development", :assets], Rails.groups(:assets => %w(development))
+
+      Rails.env = "test"
+      assert_equal [:default, "test"], Rails.groups(:assets => [:development])
+
+      ENV["RAILS_GROUPS"] = "javascripts,stylesheets"
+      assert_equal [:default, "test", "javascripts", "stylesheets"], Rails.groups
+    end
+
     test "Rails.application is nil until app is initialized" do
       require 'rails'
       assert_nil Rails.application