'Test the get order IDs function in order book'

def test_get_order_ids(self):

    self.assertFalse(self.order_book.get_order_ids())
    self.order_book.insert_ask(self.ask)
    self.order_book.insert_bid(self.bid)
    self.assertEqual(len(self.order_book.get_order_ids()), 2)
