Mike Fleetwood authored Oct 09, 2017 and Curtis Gedak committed Apr 30, 2018

As noted in comments:

1) This is white box testing because it uses implementation knowledge
   to look through the API to the internals of the password store.

2) It is not currently possible to test that the passwords are zeroed
   when the store is destroyed.
   However zeroing of memory is being tested when individual passwords
   are erased.

Bug 795617 - Implement opening and closing of LUKS mappings