Removing value check

django_q/models.py

@@ -138,8 +138,6 @@ class Failure(Task):
 
 # Optional Cron validator
 def validate_cron(value):
-    if not value:
-        return
     if not croniter:
         raise ImportError(_("Please install croniter to enable cron expressions"))
     try:

django_q/tests/test_scheduler.py

@@ -102,7 +102,7 @@ def test_scheduler(broker, monkeypatch):
     assert cron_schedule.full_clean() is None
     assert cron_schedule.__unicode__() == 'django_q.tests.tasks.word_multiply'
     with pytest.raises(ValidationError):
-        cron_schedule = create_schedule('django_q.tests.tasks.word_multiply',
+        create_schedule('django_q.tests.tasks.word_multiply',
                         2,
                         word='django',
                         schedule_type=Schedule.CRON,