使用unittest.mock在Python 3中修补input()

Question

你如何使用@patch装饰器来修补内置的input()函数？

例如,这是我要测试的question.py中的一个函数,它包含对input()的调用:

def query_yes_no(question, default="yes"):
""" Adapted from http://stackoverflow.com/questions/3041986/python-command-line-yes-no-input """

    valid = {"yes": True, "y": True, "ye": True, "no": False, "n": False}
    if default is None:
        prompt = " [y/n] "
    elif default == "yes":
        prompt = " [Y/n] "
    elif default == "no":
        prompt = " [y/N] "
    else:
        raise ValueError("invalid default answer: '%s'" % default)

    while True:
        sys.stdout.write(question + prompt)
        choice = input().lower()

        if default is not None and choice == '':
            return valid[default]
        elif choice in valid:
            return valid[choice]
        else:
            sys.stdout.write("Please respond with 'yes' or 'no' "
                             "(or 'y' or 'n').\n")

这是我的测试,它给出了错误"ImportError:没有名为' builtins '的模块":

import unittest
from unittest.mock import patch

import question

class TestQueryYesNo(unittest.TestCase):

    @patch('__builtins__.input.return_value', 'y')
    def test_query_y(self):
        answer = question.query_yes_no("Blah?")
        self.assertTrue(answer)

Answer 1

__builtin__模块在Python 3中重命名为builtins.替换如下:

@patch('builtins.input', lambda *args: 'y')

UPDATE

input有一个可选参数.更新代码以接受可选参数.

Answer 2

或者使用 Mock 的return_value属性。我无法让它作为装饰器工作，但这里是如何使用上下文管理器来做到这一点：

>>> import unittest.mock
>>> def test_input_mocking():
...     with unittest.mock.patch('builtins.input', return_value='y'):
...         assert input() == 'y'
...
>>> def test_input_mocking():
...     with unittest.mock.patch('builtins.input', return_value='y'):
...         assert input() == 'y'
...         print('we got here, so the ad hoc test succeeded')
...
>>> test_input_mocking()
we got here, so the ad hoc test succeeded
>>>