There is a lot of mock objects needed: we bypass calls to Koji, use a
mock FileCache that does not need valid RPMs on disk and avoid any
multithreading.
The test data in tests/fixtures/tagged-rpms.json comes from Koji. It is
filtered down to only a few packages to make it manageable.
Signed-off-by: Lubomír Sedlář <lsedlar@redhat.com>
