问修复python/nose2 2/bin/nose2 2:找不到

EN

import unittest


class ShoppingCartTestCases(unittest.TestCase):

def setUp(self):
    self.cart = ShoppingCart()
    self.shop = Shop()

def test_cart_property_initialization(self):
    self.assertEqual(self.cart.total, 0, msg='Initial value of total not correct')
    self.assertIsInstance(self.cart.items, dict, msg='Items is not a dictionary')

def test_add_item(self):
    self.cart.add_item('Mango', 3, 10)

    self.assertEqual(self.cart.total, 30, msg='Cart total not correct after adding items')
    self.assertEqual(self.cart.items['Mango'], 3, msg='Quantity of items not correct after adding item')

def test_remove_item(self):
    self.cart.add_item('Mango', 3, 10)
    self.cart.remove_item('Mango', 2, 10)

    self.assertEqual(self.cart.total, 10, msg='Cart total not correct after removing item')
    self.assertEqual(self.cart.items['Mango'], 1, msg='Quantity of items not correct after removing item')

def test_checkout_returns_correct_balance(self):
    self.cart.add_item('Mango', 3, 10)
    self.cart.add_item('Orange', 16, 10)

    self.assertEqual(self.cart.checkout(265), 75, msg='Balance of checkout not correct')
    self.assertEqual(self.cart.checkout(25), 'Cash paid not enough', msg='Balance of checkout not correct')

def test_shop_is_instance_of_shopping_cart(self):
    self.assertTrue(isinstance(self.shop, ShoppingCart), msg='Shop is not a subclass of ShoppingCart')

def test_shop_remove_item_method(self):
    for i in range(15):
        self.shop.remove_item()

    self.assertEqual(self.shop.quantity, 85)

class ShoppingCart(object):

    def __init__(self):
        self.total = 0
        self.items = {}

    def add_item(self, item_name, quantity, price):
        if item_name and quantity >= 1:
            self.items.update({item_name : quantity})
        if quantity and price >= 1:
            self.total += (quantity * price)

    def remove_item(self, item_name, quantity, price):
        self.total -= (quantity * price)
        if quantity >= self.items[item_name]:
            try:
                del self.items[item_name]
            except (KeyError, ValueError):
                return None
        self.items[item_name] -= quantity

    def checkout(self, cash_paid):
        balance = 0
        if cash_paid < self.total:
            return "Cash paid not enough"
        balance = cash_paid - self.total
        return balance

class Shop(ShoppingCart):

    def __init__(self):
        ShoppingCart.__init__(self)
        self.quantity = 100

    def remove_item(self):
        self.quantity -= 1