This aims to bring some consistency to the location of the tests for this class.
Includes adding the missing `@covers` tags.
Follow-up to [36177], [51622], [54250].
Props pbearne, SergeyBiryukov.
See #56793, #56782.
git-svn-id: https://develop.svn.wordpress.org/trunk@54710 602fd350-edb4-49c9-b593-d223f7449a82