def test_number_of_attendees_increasing(self):
        event = Event.objects.get(slug='test_event_0')
        event.attendance = 0  # testing for numeric case
        event.save()

        data = {
            'task-role': self.learner.pk,
            'task-event': event.pk,
            'task-person_1': self.spiderman.pk,
        }
        self.client.post(reverse('event_edit', args=[event.pk]), data)
        event.refresh_from_db()
        assert event.attendance == 1
Ensure event.attendance gets bigger after adding new learners.
dataset/ETHPy150Open swcarpentry/amy/workshops/test/test_event.py/TestEventViews.test_number_of_attendees_increasing