Python:为什么 unittest assertEqual 在这些列表上抛出错误而不是失败

Python 2.7 和 3.4:为什么 test_unexpected_error 测试抛出错误而不是失败？

import unittest 
 
 
class TestLists(unittest.TestCase): 
 
    def test_unexpected_error(self): 
        self.assertEqual([0] * 1000 + [1], [1] + [0] * 1000) 
 
    def test_fails_as_expected(self): 
        self.assertEqual([0] * 1000 + [1], [0] * 1000 + [0]) 
 
 
if __name__ == '__main__': 
    unittest.main() 

错误是:

RuntimeError: maximum recursion depth exceeded while calling a Python object 

回溯(删节——递归错误是递归错误是递归错误是....)

Traceback (most recent call last): 
  File "sotest.py", line 7, in test_unexpected_error 
    self.assertEquals([0] * 1000 + [1], [1] + [0] * 1000) 
  File "/usr/lib/python2.7/unittest/case.py", line 513, in assertEqual 
    assertion_func(first, second, msg=msg) 
  File "/usr/lib/python2.7/unittest/case.py", line 743, in assertListEqual 
    self.assertSequenceEqual(list1, list2, msg, seq_type=list) 
  File "/usr/lib/python2.7/unittest/case.py", line 722, in assertSequenceEqual 
    pprint.pformat(seq2).splitlines())) 
  File "/usr/lib/python2.7/difflib.py", line 920, in compare 
    for line in g: 
  File "/usr/lib/python2.7/difflib.py", line 1038, in _fancy_replace 
    for line in self._fancy_helper(a, best_i+1, ahi, b, best_j+1, bhi): 
  File "/usr/lib/python2.7/difflib.py", line 1051, in _fancy_helper 
    for line in g: 
  File "/usr/lib/python2.7/difflib.py", line 1038, in _fancy_replace 
    for line in self._fancy_helper(a, best_i+1, ahi, b, best_j+1, bhi): 
  File "/usr/lib/python2.7/difflib.py", line 1051, in _fancy_helper 
    for line in g: 
  File "/usr/lib/python2.7/difflib.py", line 1038, in _fancy_replace 
    for line in self._fancy_helper(a, best_i+1, ahi, b, best_j+1, bhi): 
  File "/usr/lib/python2.7/difflib.py", line 1051, in _fancy_helper 
    for line in g: 
 
(...) 
 
  File "/usr/lib/python2.7/difflib.py", line 965, in _fancy_replace 
    cruncher = SequenceMatcher(self.charjunk) 
  File "/usr/lib/python2.7/difflib.py", line 219, in __init__ 
    self.set_seqs(a, b) 
  File "/usr/lib/python2.7/difflib.py", line 231, in set_seqs 
    self.set_seq2(b) 
  File "/usr/lib/python2.7/difflib.py", line 285, in set_seq2 
    self.__chain_b() 
  File "/usr/lib/python2.7/difflib.py", line 318, in __chain_b 
    for i, elt in enumerate(b): 
RuntimeError: maximum recursion depth exceeded while calling a Python object 

请您参考如下方法:

这看起来是一个已知的 bug .

如果您不希望单元测试在失败时显示列表之间的差异，您可以执行此替代测试:

self.assertTrue([0] * 1000 + [1] == [1] + [0] * 1000)