【提问】Python执行nosetests测试时，出现AssertionError和TypeError

Electro01

1. class ParserError(Exception):
   
2.     pass
   
3. 
   
4. class Sentence(object):
   
5. 
   
6.     def __init__(self, subject, verb, object):
   
7. self.subject = subject [1]
   
8.         self.verb = verb[1]
   
9.         self.object = object[1]
   
10. 
    
11. def peek(word_list):
    
12.     if word_list:
    
13.         word = word_list[0]
    
14.         return word[0]
    
15.     else:
    
16.         return None
    
17. 
    
18. def match(word_list, expecting):
    
19. if word_list:
    
20.         word = word_list.pop(0)
    
21. 
    
22.         if word[0] == expecting:
    
23.             return word
    
24.         else:
    
25.             return None
    
26.     else:
    
27.         return None
    
28. 
    
29. def skip (word_list, word_type):
    
30.     while peek(word_list) == word_type:
    
31.         match(word_list, word_type)
    
32. 
    
33. def parse_verb(word_list):
    
34.     skip(word_list, 'stop')
    
35. 
    
36.     if peek(word_list) == 'verb':
    
37.         return match(word_list, 'verb')
    
38.     else:
    
39.         raise ParserError("Expected a verb next.")
    
40. 
    
41. 
    
42. def parse_object(word_list):
    
43.     skip(word_list,'stop')
    
44.     next = peek(word_list)
    
45. 
    
46.     if next == 'noun':
    
47.         return match(word_list, 'noun')
    
48.     if next == 'direction':
    
49.         return match(word_list, 'direction')
    
50.     else:
    
51.         raise ParserError('Expected a noun or direction next.')
    
52. 
    
53. def parse_subject(word_list, subj):
    
54.     verb = parse_verb(word_list)
    
55.     obj = parse_object(word_list)
    
56. 
    
57.     return Sentence(subj, verb, obj) # 执行 class Sentence
    
58. 
    
59. def parse_sentence(word_list):
    
60.     skip(word_list, 'stop')
    
61. 
    
62.     start = peek(word_list)
    
63. 
    
64.     if start == 'noun':
    
65.         subj = match(word_list, 'noun')
    
66.         return parse_sentence(word_list, subj)
    
67.     elif start == 'verb':
    
68.         # assume the subject is the player then
    
69.         return parse_subject(word_list, ('noun', 'player'))
    
70.     else:
    
71.         raise ParserError("Must start with subject, object, or verb not: %s" % start)

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以上是需要测试的代码。
这是我写的测试代码，其中两部分错误较相似：

1. word_listA = [('verb','elsker'),('direction','ikke'),('noun','Jag')]
   
2. def test_sentence():
   
3.     sentence = Sentence([('noun','Jag'), ('verb', 'elsker'), ('direction', 'ikke')])
   
4.     assert_equal(sentence.subject, 'Jag')

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1. def test_parse_sentence():
   
2.     result = parse_sentence([('verb','elsker'),('noun','Jag')])
   
3.     assert_equal(result.subject, 'player')
   
4.     assert_equal(result.verb, 'elsker')
   
5.     assert_equal(result.object, 'Jag')
   
6. 
   
7.     result1 = parse_sentence([('noun','Jag'), ('verb','elsker'),('direction','ikke')])
   
8.     assert_equal(result1.subject, 'Jag')
   
9.     assert_equal(result1.verb, 'elsker')
   
10.     assert_equal(result1.object, 'ikke')
    
11. 
    
12.     assert_raises(ParserError, parse_object,[('stop','in'),('stop','the')])
    

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执行nosetests后，报错：

Traceback (most recent call last):

  File "/Library/Python/2.7/site-packages/nose-1.3.7-py2.7.egg/nose/case.py", line 197, in runTest

    self.test(*self.arg)

  File "/Users/admin/mystuff/test/ex49_tests.py", line 6, in test_sentence

    sentence = Sentence([('noun','Jag'), ('verb', 'elsker'), ('direction', 'ikke')])

TypeError: __init__() takes exactly 4 arguments (2 given)

======================================================================

Traceback (most recent call last):

  File "/Library/Python/2.7/site-packages/nose-1.3.7-py2.7.egg/nose/case.py", line 197, in runTest

    self.test(*self.arg)

  File "/Users/admin/mystuff/test/ex49_tests.py", line 68, in test_parse_sentence

    result1 = parse_sentence([('noun','Jag'), ('verb','elsker'),('direction','ikke')])

  File "/Users/admin/mystuff/test/ex49.py", line 70, in parse_sentence

TypeError: parse_sentence() takes exactly 1 argument (2 given)

这是另一部分及其AssertionError报错:

1. def test_skip():
   
2.     skipA = skip([('noun','Jag'), ('verb', 'elsker')], 'verb')
   
3.     assert_equal(skipA, ('verb', 'elsker'))
   
4.     assert_equal(skipA, None)

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Traceback (most recent call last):

  File "/Library/Python/2.7/site-packages/nose-1.3.7-py2.7.egg/nose/case.py", line 197, in runTest

    self.test(*self.arg)

  File "/Users/admin/mystuff/test/ex49_tests.py", line 27, in test_skip

    assert_equal(skipA, ('verb', 'elsker'))

AssertionError: None != ('verb', 'elsker')

crossin先生

报错的内容不是都输出了吗，到标准的行那里去检查

一个是你 __init__ 参数，也就是创建对象时候给的参数不对
一个是 skipA 的值是 None

Electro01

crossin先生 发表于 2017-8-29 14:14
报错的内容不是都输出了吗，到标准的行那里去检查

一个是你 __init__ 参数，也就是创建对象时候给的参数不 ...

有点不明白她书中给出的expecting具体是指的什么

1. def match(word_list, expecting):
   
2.     # 用pop( )的方法删除这个元素，并且它还返回这个元素
   
3.     if word_list:
   
4.         word = word_list.pop(0)
   
5. 
   
6.         if word[0] == expecting:
   
7.             return word
   
8.         else:
   
9.             return None
   
10.     else:
    
11.         return None

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我给进去的list[('verb', 'taste'),('direction','good'),('noun','pizza')]第一个就是verb并且等于word_type ：'verb'
按理说应该是匹配的，然而skipA的值是None也就是说('verb', 'taste') != expecting 咯？

1. Traceback (most recent call last):
   
2.   File "/Library/Python/2.7/site-packages/nose-1.3.7-py2.7.egg/nose/case.py", line 197, in runTest
   
3.     self.test(*self.arg)
   
4.   File "/Users/admin/mystuff/test/ex49_tests.py", line 60, in test_parse_subject
   
5.     result = parse_subject([('verb', 'taste'), ('direction', 'good'),('noun','pizza')])
   
6. TypeError: parse_subject() takes exactly 2 arguments (1 given)
   
7. 
   
8. ======================================================================
   
9. ERROR: ex49_tests.test_parse_sentence
   
10. ----------------------------------------------------------------------
    
11. Traceback (most recent call last):
    
12.   File "/Library/Python/2.7/site-packages/nose-1.3.7-py2.7.egg/nose/case.py", line 197, in runTest
    
13.     self.test(*self.arg)
    
14.   File "/Users/admin/mystuff/test/ex49_tests.py", line 77, in test_parse_sentence
    
15.     result1 = parse_sentence([('noun','pizza'),('verb','taste'),('direction','good')])
    
16.   File "/Users/admin/mystuff/test/ex49.py", line 74, in parse_sentence
    
17.     return parse_sentence(word_list, subj)
    
18. TypeError: parse_sentence() takes exactly 1 argument (2 given)

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还有一个没有搞明白的错误是：

1. Traceback (most recent call last):
   
2.   File "/Library/Python/2.7/site-packages/nose-1.3.7-py2.7.egg/nose/case.py", line 197, in runTest
   
3.     self.test(*self.arg)
   
4.   File "/Users/admin/mystuff/test/ex49_tests.py", line 65, in test_parse_subject
   
5.     result1 = parse_subject([('direction', 'good') ,('noun','pizza'),('verb', 'taste')],('verb', 'taste'))
   
6.   File "/Users/admin/mystuff/test/ex49.py", line 62, in parse_subject
   
7.     verb = parse_verb(word_list)
   
8.   File "/Users/admin/mystuff/test/ex49.py", line 46, in parse_verb
   
9.     raise ParserError("Expected a verb next.")
   
10. ParserError: Expected a verb next.

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在parse_subject中：

1. def parse_subject(word_list, subj):
   
2.     verb = parse_verb(word_list)
   
3.     obj = parse_object(word_list)
   
4. 
   
5.     return Sentence(subj, verb, obj)

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verb里面要求传入的list第一个是verb, 而obj中要求第一个传入的是noun或者direction
所以在测试代码中：

1. def test_parse_subject():
   
2.     result = parse_subject([('verb', 'taste'), ('direction', 'good'),('noun','pizza')],('noun','pizza'))
   
3.     assert_equal(result.subject, 'pizza')
   
4.     assert_equal(result.verb, 'taste')
   
5.     assert_equal(result.object, 'good')
   
6. 
   
7.     result1 = parse_subject([ ('direction', 'good'),('noun','pizza'),('verb', 'taste')],('none', 'pizza'))
   
8.     assert_equal(result.subject, 'pizza')
   
9.     assert_equal(result.verb, 'taste')
   
10.     assert_equal(result.object, 'good')

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result中第一个传入的是verb，为了测试    verb = parse_verb(word_list) 所以没有报错
result1中第一个传入的direction 为了测试  obj = parse_object(word_list) 但是报错了

1. Traceback (most recent call last):
   
2.   File "/Library/Python/2.7/site-packages/nose-1.3.7-py2.7.egg/nose/case.py", line 197, in runTest
   
3.     self.test(*self.arg)
   
4.   File "/Users/admin/mystuff/test/ex49_tests.py", line 65, in test_parse_subject
   
5.     result1 = parse_subject([('direction', 'good'),('verb', 'taste'),('noun','pizza')],('noun','pizza'))
   
6.   File "/Users/admin/mystuff/test/ex49.py", line 62, in parse_subject
   
7.     verb = parse_verb(word_list)
   
8.   File "/Users/admin/mystuff/test/ex49.py", line 46, in parse_verb
   
9.     raise ParserError("Expected a verb next.")
   
10. ParserError: Expected a verb next.

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如果我将传入的list中第一个改为verb，即[('verb', 'taste'), ('direction', 'good'),('noun','pizza')],('noun','pizza')
它就不会报错了，请问这是为什么呢？（即使obj中同样要求第一个传入的是noun或者direction）

然后关于最后一个报错：

1. Traceback (most recent call last):
   
2.   File "/Library/Python/2.7/site-packages/nose-1.3.7-py2.7.egg/nose/case.py", line 197, in runTest
   
3.     self.test(*self.arg)
   
4.   File "/Users/admin/mystuff/test/ex49_tests.py", line 77, in test_parse_sentence
   
5.     result1 = parse_sentence([('noun','pizza'),('verb','taste'),('direction','good')])
   
6.   File "/Users/admin/mystuff/test/ex49.py", line 74, in parse_sentence
   
7.     return parse_sentence(word_list, subj)
   
8. TypeError: parse_sentence() takes exactly 1 argument (2 given)
   

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parse_sentence() 中只能传入一个参数，而我的测试代码中    result1 = parse_sentence([('noun','pizza'),('verb','taste'),('direction','good')])只有一个list，并且第一个为('noun','pizza')，符合

1.     if start == 'noun':
   
2.         subj = match(word_list, 'noun')
   
3.         return parse_sentence(word_list, subj)

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但是它还是显示的2 given

对于  result = parse_sentence([('verb','taste'),('noun','pizza'),('direction','good')])，我传入的也是的一个list，只是开头第一个是verb符合

1.    
   
2.     elif start == 'verb':
   
3.         # assume the subject is the player then
   
4.         return parse_subject(word_list, ('noun', 'player'))

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如果删除result1，只对result1进行测试就没有报错了。请问result1中的TypeError: parse_sentence() takes exactly 1 argument (2 given)究竟是哪里出错了呢？

crossin先生

请先看看教程里关于函数的参数传递。你对函数传递理解有问题，以你最后一个为例：

1. return parse_subject(word_list, ('noun', 'player'))

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这个parse_subject 传了两个参数进去，报错说你 parse_sentence() takes exactly 1 argument (2 given) 这应该很明白吧

要不然就是你没看明白报错在说什么，仔细对照下报错给你的行数。

先把这个问题导致的错误都解决掉，剩下的还有想不通的我们再看。别一贴就是一整屏的代码，这个给人压力有点大，别人也没信心帮你看了

Electro01

crossin先生 发表于 2017-8-29 23:19
请先看看教程里关于函数的参数传递。你对函数传递理解有问题，以你最后一个为例：这个parse_subject 传了两 ...

嗯，好的。谢谢啦，TypeError这个问题已经解决了
但是就是不明白给进去的是list[('verb', 'taste'),('direction','good'),('noun','pizza')]第一个的word_type就是‘verb’并且与其word_type - 'verb'相同
按理说应该是匹配的，然而skipA的值是None
这个地方我没有想明白

crossin先生

Electro01 发表于 2017-8-30 00:19
嗯，好的。谢谢啦，TypeError这个问题已经解决了
但是就是不明白给进去的是list[('verb', 'taste'),('dir ...

skip 这个函数你本身就没有给任何返回值啊
还是函数相关的概念

另外多输出，一步步查看结果

Electro01

crossin先生 发表于 2017-8-30 09:43
skip 这个函数你本身就没有给任何返回值啊
还是函数相关的概念

好哒 明白了 谢谢~