test rows for validity

Change-Id: I501c1c18df96b5b2ad628e86cfb724a541d5c4b6
Reviewed-on: https://gerrit.libreoffice.org/13169
Reviewed-by: Eike Rathke <erack@redhat.com>
Tested-by: Eike Rathke <erack@redhat.com>