nosetest錯誤：ValueError：字典更新序列元素＃0具有長度4; 2是必需的

Question

我是一個noob，這是w/r/t python 2.7和一個練習我正在努力通過瞭解Python的難題（link to ex47） - 下面的文件名爲ex47_tests.py，我得到的錯誤與運行nosetests到我在工作目錄

據nosetests，錯誤是在該行west.add_paths({'east', start})的test_map()功能，它指出：ValueError: dictionary update sequence at element #0 has length 4; 2 is required，但我不明白是什麼問題...這是測試文件：

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

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

作爲參考，game.py文件包含Room類具有add_paths函數（方法）：

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) 

我檢查了幾次，我已經成功地在遊戲中運行的代碼west.add_paths({'east', start}) .py文件，但是當我運行nosetests時，我不斷收到相同的錯誤。在發生錯誤的代碼中，我的解釋是，west包含一個空的{}，應該沒有問題update，否？有人可以提供一些見解，爲什麼這不起作用，錯誤來自哪裏？

非常感謝。

Answer 1

在代碼中的錯誤是從這個函數來：

west.add_paths({'east', start}) 

修正與此進行，是要與字典更新，沒有一套：

west.add_paths({'east': start}) 

當您嘗試更新帶有集的字典時，此錯誤對於以下示例是可重現的：

>>> d = {} 
>>> d.update({'east','start'}) 
Traceback (most recent call last): 
    File "<stdin>", line 1, in <module> 
ValueError: dictionary update sequence element #0 has length 5; 2 is required 

爲客戶提供更清晰的錯誤，如果你去你的解釋，並檢查該類型：

通知「東」和「啓動」

>>> print(type({'east', 'start'})) 
<type 'set'> 

通知東之間」冒號之間的逗號'和‘開始’

>>> print(type({'east': 'start'})) 
<type 'dict'>