在进行 LPTHW 练习 47 时出现断言错误答案

【问题标题】：getting assertion error while doing exercise 47 of LPTHW在进行 LPTHW 练习 47 时出现断言错误
【发布时间】：2012-09-14 12:54:32
【问题描述】：

我正在做 Learn Python the hard way 的练习 47，我收到一条错误消息：

Traceback (most recent call last):
File "c:\python26\lib\site-packages\nose-1.2.0-py2.6.egg\nose
97, in runTest
self.test(*self.arg)
File "E:\project\ex47\tests\ex47_tests.py", line 27, in test_
assert_equal(start.go('down').go('up'),start)
AssertionError: None != <ex47.game.Room object at 0x0191BFD0>

#while executing the below code: 

from nose.tools import *
from ex47.game import Room

def test_room():
    gold=Room("GoldRoom",
                """This room has gold in it you can grab. There's a
                door to the north.""")
    assert_equal(gold.name,"GoldRoom")
    assert_equal(gold.paths,{})

def test_room_paths():
    center = Room("Center","Test room in the center.")
    north = Room("North","Test room in the north.")
    south = Room("South", "Test room in the south.")
    center.add_paths({'north':north,'south': south})
    assert_equal(center.go('north'),north)
    assert_equal(center.go('south'),south)

def test_map():
    start = Room("start", "You can go west and down a hole.")
    west = Room("Trees","There are trees here, you can go east.")
    down = Room("Dungeon","It's dark down here, you can go up.")
    start.add_paths({'west':west,'down':down})
    west.add_paths({'east':start})
    assert_equal(start.go('west'),west)
    assert_equal(start.go('west').go('east'),start)
    assert_equal(start.go('down').go('up'),start)

我在谷歌上搜索，发现它是在我们调试时引发的，但也可能是我的 game.py 文件位于 bin 文件夹中的原因

整体结构是这样的

项目/ex47/bins/
/文档
/tests/ex47_tests.py, _ _ init_ _ .py
/ex47/game.py

谁能帮助我并告诉我为什么会出现此错误？

这是 game.py 文件。

class Room(object):
    def __init__(self,name,description):
        self.name = name
        self.description = description
        self.paths={}


    def go(self,direction):
        return self.paths.get(direction,None)

    def add_paths(self,paths):
        self.paths.update(paths)

【问题讨论】：

标签： python debugging assertion

【解决方案1】：

您从未将up 路径添加到您的down 房间。

down = Room("Dungeon","It's dark down here, you can go up.")

所以你的失败就在这条线上

assert_equal(start.go('down').go('up'),start)

start.go('down') 返回down Room 对象，该对象没有up 的路径。它从您的get() 调用返回None，并再次比较start 对象。提出断言是因为None != start

看起来你需要这条线：

down.add_paths({'up', start})

【讨论】：

【解决方案2】：

您没有显示您正在测试的实际代码，但某处可能缺少return 语句。

【讨论】：