1. Have AutoRenewalNotices set to "according to patron messaging preferences"
2. Make some patron checkouts eligible from auto_renewal
3. Turn on SMS and Digest only Auto renewal messaging prefs for that patron
4. By default there is no SMS template for AUTO_RENEWALS_DGST, leave it that way
5. Run automatic_renewal.pl
When it hits that patron you'll see:
No circulation AUTO_RENEWALS_DGST letter transported by sms at /kohadevbox/koha/C4/Letters.pm line 633.
no letter of type 'AUTO_RENEWALS_DGST' found for borrowernumber 5. Please see sample_notices.sql at /kohadevbox/koha/misc/cronjobs/automatic_renewals.pl line 304.
Can't use string ("1") as a HASH ref while "strict refs" in use at /kohadevbox/koha/C4/Letters.pm line 947.
The job dies at this point. It would be better if it just skipped sending this patron a notice and carried on.
*** This bug has been marked as a duplicate of bug 30354 ***