FileManagedTestBase is supposed to be used for testing managed files. However, quite a number of important functions for testing managed files are only present in FileFieldTestBase:
- getLastFileId()
- assertFileExists()
- assertFileEntryExists()
- assertFileNotExists()
- assertFileEntryNotExists()
- assertFileIsPermanent()
- and the missing: assertFileIsTemporary().
To be more useful in Core as well as in contrib tests, these functions should be present on FileManagedTestBase, which may then be extended by FileFieldTestBase for some more field-related functionality.