This checks that the addon being indexed goes into the old index. We could probably add another test to assert that the index task is getting called and passing in each index. E.g. (1) Create an addon, (2) Create the reindex record in the table, (3) Mock the index method, (4) call `save` on the addon and verify it calls the indexing method twice with each index. That'll cover the case that it should index into the new index which this isn't doing (unless I missed it). Oh wait, you're searching below after indexes have been re-aliased it looks like. Disregard unless you think this is a good extra to have then.