assertRaises没有发现错误

Question

我有此脚本

import unittest,itertools,random 

##testclass 
class Testcomb(unittest.TestCase): 

    def test_input(self): 
     self.assertRaises(TypeError,calculate_combinations,dict(comb1), 5) 

def calculate_combinations(combin,target): 
    counter = 0 
    for L in range(0, len(combin)+1): 
     for subset in itertools.combinations(combin, L): 
     if sum(subset) == target: counter= counter+1 
    return counter 

comb1=[1,2,3,4] 


if __name__=='__main__': unittest.main() 

但self.assertRaises(TypeError,calculate_combinations,dict(comb1), 5)不拦截异常给我这个错误：

E.. 
====================================================================== 
ERROR: test_input (__main__.Testcomb) 
---------------------------------------------------------------------- 
Traceback (most recent call last): 
    File "total_combination.py", line 25, in test_input 
    self.assertRaises(TypeError,calculate_combinations,dict(comb1), 5) 
TypeError: cannot convert dictionary update sequence element #0 to a sequence 

---------------------------------------------------------------------- 
Ran 3 tests in 0.000s 

FAILED (errors=1) 

谁能帮助？

Answer 1

使您的测试失败的异常由断言的dict(comb1)部分触发。

>>> comb1=[1,2,3,4] 
>>> dict(comb1) 
Traceback (most recent call last): 
    File "<stdin>", line 1, in <module> 
TypeError: cannot convert dictionary update sequence element #0 to a sequence 

相反，在assertRaises将返回True只有当它是可调用的（在你的情况calculate_combinations）来触发它。

HTH！