[英]Python: AssertionError
首先,這是我需要測試的代碼:
class ParserError(Exception):
pass
class Sentence(object):
def __init__(self, subject, verb, object):
self.subject = subject [1]
self.verb = verb[1]
self.object = object[1]
def peek(word_list):
if word_list:
word = word_list[0]
return word[0]
else:
return None
def match(word_list, expecting):
if word_list:
word = word_list.pop(0)
if word[0] == expecting:
return word
else:
return None
else:
return None
def skip (word_list, word_type):
while peek(word_list) == word_type:
match(word_list, word_type)
def parse_verb(word_list):
skip(word_list, 'stop')
if peek(word_list) == 'verb':
return match(word_list, 'verb')
else:
raise ParserError("Expected a verb next.")
def parse_object(word_list):
skip(word_list,'stop')
next = peek(word_list)
if next == 'noun':
return match(word_list, 'noun')
if next == 'direction':
return match(word_list, 'direction')
else:
raise ParserError('Expected a noun or direction next.')
def parse_subject(word_list, subj):
verb = parse_verb(word_list)
obj = parse_object(word_list)
return Sentence(subj, verb, obj) # 執行 class Sentence
def parse_sentence(word_list):
skip(word_list, 'stop')
start = peek(word_list)
if start == 'noun':
subj = match(word_list, 'noun')
return parse_sentence(word_list, subj)
elif start == 'verb':
# assume the subject is the player then
return parse_subject(word_list, ('noun', 'player'))
else:
raise ParserError("Must start with subject, object, or verb not: %s" % start)
我輸入的列表是[('verb','taste'),('direction','good'),('noun','pizza')]此列表中的第一個值是('verbs,' ”,其word_type為“動詞”,適合我在編碼中給出的word_type,但出現錯誤AssertionError:None!='動詞'我認為這是不合理的。
def test_skip():
skipA = skip([('verb','taste'),('direction','good'),('noun','pizza')], 'verb')
assert_equal(skipA, 'verb')
# assert_equal(skipA, None)
函數skip
不返回任何值(這意味着它返回None
)。
因此skipA
為None
,斷言失敗。
使用“跳過”方法可能會出現問題,因為“跳過”未返回任何值,這意味着“跳過”將返回None
您需要在跳過功能中返回。 您將返回查看和匹配,但是您調用skip並希望從那里獲取值的范圍意味着您也需要從那里返回。
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