我们可以使用pytest-mock (https://pypi.org/project/pytest-mock/)模拟器对象来模拟特定模块中的日期时间行为

假设您想在以下文件中模拟日期时间

# File path - source_dir/x/a.py
import datetime

def name_function():
     name = datetime.now()
     return f"name_{name}"

在测试函数中，mock将在测试运行时添加到函数中

def test_name_function(mocker):
     mocker.patch('x.a.datetime')
     x.a.datetime.now.return_value = datetime(2019, 1, 1)

     actual = name_function()

     assert actual == "name_2019-01-01"

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。

另一种选择是使用 https://github.com/spulec/freezegun/

安装:

pip install freezegun

并使用它:

from freezegun import freeze_time

@freeze_time("2012-01-01")
def test_something():

    from datetime import datetime
    print(datetime.now()) #  2012-01-01 00:00:00

    from datetime import date
    print(date.today()) #  2012-01-01

它还会影响其他模块的方法调用中的其他datetime调用:

other_module.py:

from datetime import datetime

def other_method():
    print(datetime.now())    

main.py:

from freezegun import freeze_time

@freeze_time("2012-01-01")
def test_something():

    import other_module
    other_module.other_method()

最后:

$ python main.py
# 2012-01-01

http://blog.xelnor.net/python-mocking-datetime/中讨论了几种解决方案。总而言之:

模拟对象-简单有效，但打破isinstance()检查:

target = datetime.datetime(2009, 1, 1)
with mock.patch.object(datetime, 'datetime', mock.Mock(wraps=datetime.datetime)) as patched:
    patched.now.return_value = target
    print(datetime.datetime.now())

模拟类

import datetime
import mock

real_datetime_class = datetime.datetime

def mock_datetime_now(target, dt):
    class DatetimeSubclassMeta(type):
        @classmethod
        def __instancecheck__(mcs, obj):
            return isinstance(obj, real_datetime_class)

    class BaseMockedDatetime(real_datetime_class):
        @classmethod
        def now(cls, tz=None):
            return target.replace(tzinfo=tz)

        @classmethod
        def utcnow(cls):
            return target

    # Python2 & Python3 compatible metaclass
    MockedDatetime = DatetimeSubclassMeta('datetime', (BaseMockedDatetime,), {})

    return mock.patch.object(dt, 'datetime', MockedDatetime)

使用:

with mock_datetime_now(target, datetime):
   ....

对我来说，最好的方法是结合@Daniel G和@frx08的解决方案:

class Test_mock_date:
    class NewDate(datetime.datetime):
        @classmethod
        def now(cls, tz=None):
            return cls(2021, 5, 12)

    def test_mock_date(self):
        with patch('datetime.datetime', new = self.NewDate):
            assert datetime.datetime.now() == datetime.datetime(2021, 5, 12, 0, 0)

你可以看看下面我写的关于如何使用MagicMock的不同示例的中型文章https://medium.com/@camposer/d2113513b365

在Daniel G的解决方案中补充一点:

from datetime import date

class FakeDate(date):
    "A manipulable date replacement"
    def __new__(cls, *args, **kwargs):
        return date.__new__(date, *args, **kwargs)

这将创建一个类，当实例化时，该类将返回一个正常的datetime。对象，但也可以更改。

@mock.patch('datetime.date', FakeDate)
def test():
    from datetime import date
    FakeDate.today = classmethod(lambda cls: date(2010, 1, 1))
    return date.today()

test() # datetime.date(2010, 1, 1)