'Test that overriding existing field executed create, fetch and update queries.'

def test_override_num_queries_update_existing_field(self):

    ccx_start = datetime.datetime(2014, 12, 25, 0, 0, tzinfo=pytz.UTC)
    new_ccx_start = datetime.datetime(2015, 12, 25, 0, 0, tzinfo=pytz.UTC)
    chapter = self.ccx_course.get_children()[0]
    override_field_for_ccx(self.ccx, chapter, 'start', ccx_start)
    with self.assertNumQueries(3):
        override_field_for_ccx(self.ccx, chapter, 'start', new_ccx_start)
