Expanded class hierarchy of TestFileUsage in Drupal 8
- class \Drupal\file\FileUsage\FileUsageBase implements FileUsageInterface
- class \Drupal\file\FileUsage\DatabaseFileUsageBackend
- class \Drupal\mongodb\MongodbFileUsage
- class \Drupal\service_provider_test\TestFileUsage
- class \Drupal\Tests\file\Unit\TestFileUsage