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Proper module for patching datetime.datetime.now().
# This code is in the public domain
# Author: Raphaël Barrois
from __future__ import print_function
import datetime
import mock
real_datetime_class = datetime.datetime
def mock_datetime_now(target, datetime_module):
"""Override ``datetime.datetime.now()`` with a custom target value.
This creates a new datetime.datetime class, and alters its now()/utcnow()
methods.
Returns:
A mock.patch context, can be used as a decorator or in a with.
"""
# See http://bugs.python.org/msg68532
# And http://docs.python.org/reference/datamodel.html#customizing-instance-and-subclass-checks
class DatetimeSubclassMeta(type):
"""We need to customize the __instancecheck__ method for isinstance().
This must be performed at a metaclass level.
"""
@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(datetime_module, 'datetime', MockedDatetime)
def main():
target = real_datetime_class(2009, 1, 1)
print("Entering mock")
with mock_datetime_now(target, datetime):
print("- now ->", datetime.datetime.now())
print("- isinstance(now, dt) ->", isinstance(datetime.datetime.now(), datetime.datetime))
print("- isinstance(target, dt) ->", isinstance(target, datetime.datetime))
print("Outside mock")
print("- now ->", datetime.datetime.now())
print("- isinstance(now, dt) ->", isinstance(datetime.datetime.now(), datetime.datetime))
print("- isinstance(target, dt) ->", isinstance(target, datetime.datetime))
if __name__ == '__main__':
main()
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