see bug 7410 as reference We can check if the fontconfig cache has been generated during build by checking if /var/cache/fontconfig is empty in the image
Obviously the test should verify that the fontcache should be written at all by looking for font packages being installed first.
Moved to 2.5 due resources constraint
do we still want to do this?
Such a test is not useful because images usually have fonts installed. The test would be complex and isn't worthwhile.