Rails::Engine.find(path) - method to find engine by path

railties/lib/rails/application/railties.rb

@@ -8,14 +8,6 @@ module Rails
         @all.each(&block) if block
         @all
       end
-
-      def railties
-        @railties ||= ::Rails::Railtie.subclasses.map(&:instance)
-      end
-
-      def engines
-        @engines ||= ::Rails::Engine.subclasses.map(&:instance)
-      end
     end
   end
 end

railties/lib/rails/engine.rb

@@ -371,6 +371,11 @@ module Rails
          end
         end
       end
+
+      # Finds engine with given path
+      def find(path)
+        Rails::Engine::Railties.engines.find { |r| File.expand_path(r.root.to_s) == File.expand_path(path.to_s) }
+      end
     end
 
     delegate :middleware, :root, :paths, :to => :config

railties/lib/rails/engine/railties.rb

@@ -18,6 +18,16 @@ module Rails
           Plugin.all(plugin_names, @config.paths["vendor/plugins"].existent)
         end
       end
+
+      def self.railties
+        @railties ||= ::Rails::Railtie.subclasses.map(&:instance)
+      end
+
+      def self.engines
+        @engines ||= ::Rails::Engine.subclasses.map(&:instance)
+      end
+
+      delegate :railties, :engines, :to => "self.class"
     end
   end
 end

railties/test/railties/engine_test.rb

@@ -702,5 +702,24 @@ module RailtiesTest
 
       assert_equal "foo", Bukkits.table_name_prefix
     end
+
+    test "fetching engine by path" do
+      @plugin.write "lib/bukkits.rb", <<-RUBY
+        module Bukkits
+          class Engine < ::Rails::Engine
+          end
+        end
+      RUBY
+
+      boot_rails
+      require "#{rails_root}/config/environment"
+
+      assert_equal Bukkits::Engine.instance, Rails::Engine.find(@plugin.path)
+
+      # check expanding paths
+      engine_dir = @plugin.path.chomp("/").split("/").last
+      engine_path = File.join(@plugin.path, '..', engine_dir)
+      assert_equal Bukkits::Engine.instance, Rails::Engine.find(engine_path)
+    end
   end
 end