Problem/Motivation
Please refer the problem/motivation section of #2737719: EntityResource: Provide comprehensive test coverage: for every entity type, every format, every method
Proposed resolution
Write EntityResourceTestBase subclass for the File entity.
Remaining tasks
References
1. Follow-up of #2737719: EntityResource: Provide comprehensive test coverage: for every entity type, every format, every method
2. Subtask of #2824572: [PP-14] Write EntityResourceTestBase subclasses for every other entity type.