Add unit tests to explicitly cover container member set changes.
Add unit tests to explicitly cover container member set changes.

jkonecny12/blivet,jkonecny12/blivet,vpodzime/blivet,rvykydal/blivet,AdamWill/blivet,rhinstaller/blivet,rhinstaller/blivet,vojtechtrefny/blivet,vpodzime/blivet,rvykydal/blivet,vojtechtrefny/blivet,AdamWill/blivet