4 files changed, 143 insertions, 0 deletions
diff --git a/railties/lib/rails/engine/commands.rb b/railties/lib/rails/engine/commands.rb
new file mode 100644
index 0000000000..05218640c6
--- /dev/null
+++ b/railties/lib/rails/engine/commands.rb
@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+unless defined?(APP_PATH)
+  if File.exist?(File.expand_path("test/dummy/config/application.rb", ENGINE_ROOT))
+    APP_PATH = File.expand_path("test/dummy/config/application", ENGINE_ROOT)
+  end
+end
+
+require "rails/commands"
diff --git a/railties/lib/rails/engine/configuration.rb b/railties/lib/rails/engine/configuration.rb
new file mode 100644
index 0000000000..4143b3c881
--- /dev/null
+++ b/railties/lib/rails/engine/configuration.rb
@@ -0,0 +1,90 @@
+# frozen_string_literal: true
+
+require "rails/railtie/configuration"
+
+module Rails
+  class Engine
+    class Configuration < ::Rails::Railtie::Configuration
+      attr_reader :root
+      attr_accessor :middleware
+      attr_writer :eager_load_paths, :autoload_once_paths, :autoload_paths
+
+      def initialize(root = nil)
+        super()
+        @root = root
+        @generators = app_generators.dup
+        @middleware = Rails::Configuration::MiddlewareStackProxy.new
+      end
+
+      # Holds generators configuration:
+      #
+      #   config.generators do |g|
+      #     g.orm             :data_mapper, migration: true
+      #     g.template_engine :haml
+      #     g.test_framework  :rspec
+      #   end
+      #
+      # If you want to disable color in console, do:
+      #
+      #   config.generators.colorize_logging = false
+      #
+      def generators
+        @generators ||= Rails::Configuration::Generators.new
+        yield(@generators) if block_given?
+        @generators
+      end
+
+      def paths
+        @paths ||= begin
+          paths = Rails::Paths::Root.new(@root)
+
+          paths.add "app",                 eager_load: true,
+                                           glob: "{*,*/concerns}",
+                                           exclude: %w(assets javascript)
+          paths.add "app/assets",          glob: "*"
+          paths.add "app/controllers",     eager_load: true
+          paths.add "app/channels",        eager_load: true, glob: "**/*_channel.rb"
+          paths.add "app/helpers",         eager_load: true
+          paths.add "app/models",          eager_load: true
+          paths.add "app/mailers",         eager_load: true
+          paths.add "app/views"
+
+          paths.add "lib",                 load_path: true
+          paths.add "lib/assets",          glob: "*"
+          paths.add "lib/tasks",           glob: "**/*.rake"
+
+          paths.add "config"
+          paths.add "config/environments", glob: "#{Rails.env}.rb"
+          paths.add "config/initializers", glob: "**/*.rb"
+          paths.add "config/locales",      glob: "*.{rb,yml}"
+          paths.add "config/routes.rb"
+
+          paths.add "db"
+          paths.add "db/migrate"
+          paths.add "db/seeds.rb"
+
+          paths.add "vendor",              load_path: true
+          paths.add "vendor/assets",       glob: "*"
+
+          paths
+        end
+      end
+
+      def root=(value)
+        @root = paths.path = Pathname.new(value).expand_path
+      end
+
+      def eager_load_paths
+        @eager_load_paths ||= paths.eager_load
+      end
+
+      def autoload_once_paths
+        @autoload_once_paths ||= paths.autoload_once
+      end
+
+      def autoload_paths
+        @autoload_paths ||= paths.autoload_paths
+      end
+    end
+  end
+end
diff --git a/railties/lib/rails/engine/railties.rb b/railties/lib/rails/engine/railties.rb
new file mode 100644
index 0000000000..052b74c880
--- /dev/null
+++ b/railties/lib/rails/engine/railties.rb
@@ -0,0 +1,23 @@
+# frozen_string_literal: true
+
+module Rails
+  class Engine < Railtie
+    class Railties
+      include Enumerable
+      attr_reader :_all
+
+      def initialize
+        @_all ||= ::Rails::Railtie.subclasses.map(&:instance) +
+          ::Rails::Engine.subclasses.map(&:instance)
+      end
+
+      def each(*args, &block)
+        _all.each(*args, &block)
+      end
+
+      def -(others)
+        _all - others
+      end
+    end
+  end
+end
diff --git a/railties/lib/rails/engine/updater.rb b/railties/lib/rails/engine/updater.rb
new file mode 100644
index 0000000000..be7a47124a
--- /dev/null
+++ b/railties/lib/rails/engine/updater.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require "rails/generators"
+require "rails/generators/rails/plugin/plugin_generator"
+
+module Rails
+  class Engine
+    class Updater
+      class << self
+        def generator
+          @generator ||= Rails::Generators::PluginGenerator.new ["plugin"],
+            { engine: true }, { destination_root: ENGINE_ROOT }
+        end
+
+        def run(action)
+          generator.send(action)
+        end
+      end
+    end
+  end
+end