Extract routes.rb to engine location for auto configuration

config/routes.rb

+Rails.application.routes.draw do
+  get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
+  get  "/rails/active_storage/variants/:encoded_blob_key/:encoded_variant_key/*filename" => "active_storage/variants#show", as: :rails_blob_variant
+  post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads
+
+  resolve 'ActiveStorage::Variant' do |variant|
+    encoded_blob_key    = ActiveStorage::VerifiedKeyWithExpiration.encode(variant.blob.key)
+    encoded_variant_key = ActiveStorage::Variant.encode_key(variant.variation)
+    filename            = variant.blob.filename
+
+    route_for(:rails_blob_variant, encoded_blob_key, encoded_variant_key, filename)
+  end
+end

lib/active_storage/engine.rb

@@ -14,17 +14,6 @@ class Engine < Rails::Engine # :nodoc:
       end
     end
 
-    initializer "active_storage.routes" do
-      require "active_storage/disk_controller"
-      require "active_storage/direct_uploads_controller"
-
-      config.after_initialize do |app|
-        app.routes.prepend do
-          eval(File.read(File.expand_path("../routes.rb", __FILE__)))
-        end
-      end
-    end
-
     initializer "active_storage.attached" do
       require "active_storage/attached"
 

lib/active_storage/routes.rb

-get  "/rails/active_storage/disk/:encoded_key/*filename" => "active_storage/disk#show", as: :rails_disk_blob
-get  "/rails/active_storage/variants/:encoded_key/:encoded_transformation/*filename" => "active_storage/controllers/variants#show", as: :rails_blob_variant
-post "/rails/active_storage/direct_uploads" => "active_storage/direct_uploads#create", as: :rails_direct_uploads

test/test_helper.rb

@@ -34,17 +34,6 @@ def create_blob(data: "Hello world!", filename: "hello.txt", content_type: "text
     end
 end
 
-require "action_controller"
-require "action_controller/test_case"
-
-class ActionController::TestCase
-  Routes = ActionDispatch::Routing::RouteSet.new.tap do |routes|
-    routes.draw do
-      eval(File.read(File.expand_path("../../lib/active_storage/routes.rb", __FILE__)))
-    end
-  end
-end
-
 require "active_storage/attached"
 ActiveRecord::Base.send :extend, ActiveStorage::Attached::Macros