Expanded class hierarchy of TestMemoryBackend in Drupal 9
- class \Drupal\Core\Cache\MemoryBackend implements CacheBackendInterface, CacheTagsInvalidatorInterface
- class \Drupal\Core\Cache\MemoryCache\MemoryCache implements MemoryCacheInterface
- class \Drupal\Core\Cache\MemoryCounterBackend
- class \Drupal\Tests\Core\Asset\TestMemoryBackend