Configure Rails.root to be test app dir

Author: umeda-rizap

test/fake_app.rb

@@ -11,6 +11,7 @@ class Application < Rails::Application
     config.session_store :cookie_store, :key => '_myapp_session'
     config.active_support.deprecation = :log
     config.eager_load = false
+    config.root = __dir__
   end
 end
 ActionArgsTestApp::Application.initialize!