def test_promo_fee_ids(self):
promocode = Promocode()
self.assertEqual(promocode.get_fee_ids(), None)
fee_ids = ['123', '456', '789', 'abc']
promocode.set_fee_ids(fee_ids)
self.assertEqual(len(promocode.get_fee_ids()), 4)
promocode.delete_fee_by_id('789')
self.assertFalse('789' in promocode.get_fee_ids())
promocode.delete_fee(2)
self.assertFalse('abc' in promocode.get_fee_ids())
promocode.clear_fee_ids()
self.assertFalse(promocode.get_fee_ids(), None)
