How to mock python's datetime.now() in a class method for unit testing?

You could use freezegun :

from freezegun import freeze_timedef test():    assert datetime.datetime.now() != datetime.datetime(2012, 1, 14)    with freeze_time("2012-01-14"):        assert datetime.datetime.now() == datetime.datetime(2012, 1, 14)    assert datetime.datetime.now() != datetime.datetime(2012, 1, 14)

It basically mocks datetime module calls.

You'd create a function that returns a specific datetime, localized to the timezone passed in:

import mockdef mocked_get_now(timezone):    dt = datetime.datetime(2012, 1, 1, 10, 10, 10)    return timezone.localize(dt)@mock.patch('path.to.your.models.MyClass.get_now', side_effect=mocked_get_now)def your_test(self, mock_obj):    # Within this test, `MyClass.get_now()` is a mock that'll return a predictable    # timezone-aware datetime object, set to 2012-01-01 10:10:10.

That way you can test if the resulting timezone-aware datetime is correctly being handled; results elsewhere should show the correct timezone but will have a predictable date and time.

You use the mocked_get_now function as a side-effect when mocking get_now; whenever code calls get_now the call is recorded by mock, and mocked_get_now is called, and it's return value used as the value returned to the caller of get_now.

I'm using date, but the same idea should work for datetime:

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

...

from mock import patch@patch('some.module.date', SpoofDate)def testSomething(self):    SpoofDate.today = classmethod(lambda cls : date(2012, 9, 24))

Where some.module imports date. Patch is replacing the imported date with SpoofDate, which you can then redefine to do whatever you want.