With the move to python3, testimage and tesexport can't import tests from other layers other than meta. The exception thrown is: AttributeError: 'module' object has no attribute 'testname'
Sent patches to the mailing list: http://lists.openembedded.org/pipermail/openembedded-core/2016-June/122508.html
This has been solved with commit: http://git.yoctoproject.org/cgit/cgit.cgi/poky/commit/?id=d9b3ee8b38f877c1723e48f1aa311c28102786fb