有一些问题。

首先，你使用模拟的方式。帕奇说得不太对。当用作装饰器时，它只在被装饰的函数内用Mock对象替换给定的函数/类(在本例中为datetime.date.today)。因此，只有在today()中，datetime.date.today才会是一个不同的函数，这似乎不是你想要的。

你真正想要的似乎是这样的:

@mock.patch('datetime.date.today')
def test():
    datetime.date.today.return_value = date(2010, 1, 1)
    print datetime.date.today()

不幸的是，这行不通:

>>> test()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "build/bdist.macosx-10.6-universal/egg/mock.py", line 557, in patched
  File "build/bdist.macosx-10.6-universal/egg/mock.py", line 620, in __enter__
TypeError: can't set attributes of built-in/extension type 'datetime.date'

这是失败的，因为Python内置类型是不可变的-更多细节请参阅这个答案。

在本例中，我将继承datetime的子类。日期自己，并创建正确的函数:

import datetime
class NewDate(datetime.date):
    @classmethod
    def today(cls):
        return cls(2010, 1, 1)
datetime.date = NewDate

现在你可以这样做:

>>> datetime.date.today()
NewDate(2010, 1, 1)

值得注意的是，Mock文档专门讨论了datetime.date.today，并且可以在不创建虚拟类的情况下做到这一点:

https://docs.python.org/3/library/unittest.mock-examples.html#partial-mocking

>>> from datetime import date
>>> with patch('mymodule.date') as mock_date:
...     mock_date.today.return_value = date(2010, 10, 8)
...     mock_date.side_effect = lambda *args, **kw: date(*args, **kw)
...
...     assert mymodule.date.today() == date(2010, 10, 8)
...     assert mymodule.date(2009, 6, 8) == date(2009, 6, 8)
...

您可以使用以下基于Daniel G解的方法。这个方法的优点是不会破坏isinstance(d, datetime.date)的类型检查。

import mock

def fixed_today(today):
    from datetime import date

    class FakeDateType(type):
        def __instancecheck__(self, instance):
            return isinstance(instance, date)

    class FakeDate(date):
        __metaclass__ = FakeDateType

        def __new__(cls, *args, **kwargs):
            return date.__new__(date, *args, **kwargs)

        @staticmethod
        def today():
            return today

    return mock.patch("datetime.date", FakeDate)

基本上，我们取代了基于c语言的datetime。Date类，使用我们自己的python子类，生成原始的datetime。日期实例，并响应isinstance()查询完全与本机datetime.date相同。

在测试中使用它作为上下文管理器:

with fixed_today(datetime.date(2013, 11, 22)):
    # run the code under test
    # note, that these type checks will not break when patch is active:
    assert isinstance(datetime.date.today(), datetime.date)

类似的方法可用于模拟datetime.datetime.now()函数。

对于那些在测试类中使用补丁程序的人，下面是我如何成功地修补datetime功能:

from datetime import datetime
import unittest
from unittest.mock import Mock, patch

# Replace with the proper path to the module you would
# like datetime to be mocked
from path.to.my_module

class MyTestCases(unittest.TestCase):

    def setUp(self):
        """execute on class instantiation"""
        # Record both times at the same moment
        self.dt_now, self.dt_utcnow = datetime.now(), datetime.utcnow()

        # After retrieving real (or hardcoded datetime values), 
        # proceed to mock them in desired module
        self.patch_datetime_functions()


    def patch_datetime_functions(self) -> None:
        """
        Patch datetime.now() and datetime.utcnow() to prevent issues when
        comparing expected dates
        """

        # Create a patcher
        self.patcher_dt = patch(
            'path.to.my_module'
        )

        # Start but make sure cleanup always occurs
        self.patcher_dt.start()
        self.addCleanup(self.patcher_dt.stop)

        # Perform the actual patch – use lambdas as mock functions
        datetime_mock = Mock(wraps=datetime)
        datetime_mock.now.return_value = self.dt_now
        datetime_mock.utcnow.return_value = self.dt_utcnow

        my_module.datetime = datetime_mock


    # Here's what it will look like when testing:
    def some_test(self):
        curr_dt = self.dt_now
        returned_dt = my_module.datetime.utcnow()
        
        # Compare the dates
        self.assertEqual(curr_dt, returned_dt,
            'Datetime values should be equal'
        )

我想我来晚了一点，但我认为这里的主要问题是您直接修补datetime.date.today，根据文档，这是错误的。

例如，您应该修补在测试函数所在的文件中导入的引用。

假设你有一个functions.py文件，其中包含以下内容:

import datetime

def get_today():
    return datetime.date.today()

然后，在你的测试中，你应该有这样的东西

import datetime
import unittest

from functions import get_today
from mock import patch, Mock

class GetTodayTest(unittest.TestCase):

    @patch('functions.datetime')
    def test_get_today(self, datetime_mock):
        datetime_mock.date.today = Mock(return_value=datetime.strptime('Jun 1 2005', '%b %d %Y'))
        value = get_today()
        # then assert your thing...

希望这能对你有所帮助。

我通过将datetime导入为realdatetime并将我在模拟中需要的方法替换为实际方法来完成这项工作:

import datetime as realdatetime

@mock.patch('datetime')
def test_method(self, mock_datetime):
    mock_datetime.today = realdatetime.today
    mock_datetime.now.return_value = realdatetime.datetime(2019, 8, 23, 14, 34, 8, 0)