In tests interacting with the database (writing to it), MediaWikiTestCase can help us to clean up, but it needs tablesUsed to be specified[0] to work.
Tools can help us to find the places in question, but adding the tablesUsed and thus allowing the reset could reveal sloppy setUp of other tests, that rely on previously existing entities.
[0] most tests will only require "page" to be specified as this is expanded to cover more tables that go along with it