Parsing of extension's .info.yml files is cached in the FileCache

The results of parsing an extension's info.yml file are stored in FileCache. This will result in new entries in the APCu cache. The file cache is not cleared when a cache clear is performed. The cache uses Drupal's deployment identifier and checks the file's modification time.

If a module has a test that makes rapid changes to info.yml files, the test can use \Drupal\TestTools\Extension\InfoWriterTrait to safely makes changes to info.yml files. If the test uses this trait, then it can call $this->writeInfoFile() to change or create a new .info.yml file.