Hi,
There are a few hundred tests that PackageKit runs before any release
(make check) -- these primarily test the code and the "dummy" (fake)
backend for consistency.
It would be very easy (but quite a lot of work) to set up a fake repo
for PackageKit and then test the various yum install / update / remove
combination for consistency.
This would be a great things to add as part of a GSoC or something
similar, it just needs somebody to "own" it.