Debug time limit handling

ref-test/app/admin/views.py

@@ -291,7 +291,7 @@ def _create_test():
         new_test.start_date = datetime.strptime(new_test.start_date, '%Y-%m-%dT%H:%M')
         new_test.end_date = request.form.get('expiry_date')
         new_test.end_date = datetime.strptime(new_test.end_date, '%Y-%m-%dT%H:%M')
-        new_test.time_limit = request.form.get('time_limit')
+        new_test.time_limit = None if request.form.get('time_limit') == 'none' else int(request.form.get('time_limit'))
         dataset = request.form.get('dataset')
         new_test.dataset = Dataset.query.filter_by(id=dataset).first()
         success, message = new_test.create()

ref-test/app/models/entry.py

@@ -86,7 +86,7 @@ class Entry(db.Model):
         self.answers = answers
         self.result = result
         write('tests.log', f'Test completed by {self.get_first_name()} {self.get_surname()}.')
-        delta = timedelta(minutes=self.test.time_limit+1)
+        delta = timedelta(minutes=int(0 if self.test.time_limit is None else self.test.time_limit)+1)
         if not self.test.time_limit or self.end_time <= self.start_time + delta:
             self.status = 'completed'
             self.valid = True