Do not execute rails app:update in railties/test/generators/app_generator_test.rb

[ryohashimoto]

Summary

In railties/test/generators/app_generator_test.rb test file, system("bin/rails app:update") is called several times.
Like other test cases in the test file, it is enough to call Rails::AppGenerator#update_config_files .

[ryohashimoto]

In this test case, still rails app:update need to be executed because Rails.application.config.loaded_config_version need to be obtained from loaded rails application.

[y-yagi]

Thanks!