CODEWITHSUNDEEP
python
syntacticmarmalade
syntacticmarmalade

Reputation: 71

Mocking datetime.now(); mock object isn't recognized as a class

I'm trying to mock the output of datetime.now() to simulate the passage of time. Here is what I'm trying to do:

from datetime import datetime, timedelta
from mock import Mock, patch
from other_module import some_code

tomorrow = Mock(spec=datetime)
tomorrow.now = Mock(return_value=datetime.now() + timedelta(days=1))
with patch('other_module.datetime', tomorrow):
    some_code()

This would work fine, except some_code() is using a library, croniter, that specifically takes the datetime.datetime class as input and checks that it is a subclass of datetime.datetime. This is the problem I'm running into; while datetime.datetime is a class, my mock is not; it's not recognized as a class type by the issubclass method.

How can I make sure that my mock object is recognized as a class?

Upvotes: 2

Views: 474

Answers (1)

David
David

Reputation: 681

I'm not familiar with croniter, but freezegun may help with this— it patches all references to datetime.datetime with instances of freezegun.api.FakeDatetime, so within some_code(), any datetime.datetimes should use instances of freezegun.api.FakeDatetime. Speaking from experience, you'll also save yourself lots of headaches with intermittent test failures when trying to simulate the passage of time if you use freezegun.

from datetime import datetime, timedelta
from freeze_gun import freeze_time
from other_module import some_code

fake_today = datetime.datetime(2017, 7, 11)
with_freeze_time(fake_today):
    some_code()
# simulate passage of time to tomorrow
with_freeze_time(fake_today + timedelta(days=1))
    some_code()

Upvotes: 3

Related Questions