'Test the retrieval of a tick from the order book'

def test_get_tick(self):

    self.order_book.insert_ask(self.ask)
    self.order_book.insert_bid(self.bid)
    self.assertTrue(self.order_book.get_tick(self.ask.order_id))
    self.assertTrue(self.order_book.get_tick(self.bid.order_id))
