Implements 3 test cases that covers how the cache is used.
We have to mock unlink() function because the caching code unlinks
files that are no longer valid and we don't want to do it in our tests.
Signed-off-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Jiri Denemark <jdenemar@redhat.com>
Pavel Hrdina