在python中没有类型的unittest吗? [英] unittest for none type in python?

问题描述

我只是想知道如何测试一个不返回任何东西的函数.例如，说我有这个功能:

I was just wondering how I would go about testing for a function that does not return anything. for example, say I have this function:

def is_in(char):
    my_list = []
    my_list.append(char)

然后如果我要对其进行测试:

and then if I were to test it:

class TestIsIn(unittest.TestCase):

    def test_one(self):
    ''' Test if one character was added to the list'''
    self.assertEqual(self.is_in('a'), and this is where I am lost)

我不知道该函数等于什么，因为我没有返回值 可以与之比较.

I don't know what to assert the function is equal to, since there is no return value that I could compare it to.

assertIn是否可以工作?

would assertIn work?

推荐答案

所有Python函数都返回某些内容.如果不指定返回值，则返回None.因此，如果您的目标确实是确保某些内容不会返回值，那么您可以说

All Python functions return something. If you don't specify a return value, None is returned. So if your goal really is to make sure that something doesn't return a value, you can just say

self.assertIsNone(self.is_in('a'))

(但是，这无法区分没有显式返回值的函数和具有return None的函数.)

(However, this can't distinguish between a function without an explicit return value and one which does return None.)

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