Add `app:update` task to engines

Occasionally we update the file generated by engine.
Therefore, I think that there is a task for updating as well as
application in the engine, it is convenient for updating.

1 files changed, 19 insertions, 0 deletions

diff --git a/railties/lib/rails/engine/updater.rb b/railties/lib/rails/engine/updater.rb
new file mode 100644
index 0000000000..2ecf994a5c
--- /dev/null
+++ b/railties/lib/rails/engine/updater.rb
@@ -0,0 +1,19 @@
+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