FreezeGun: Let your Python tests travel through time

FreezeGun is a library that allows your python tests to travel through time by mocking the datetime module.

Usage

Once the decorator or context manager have been invoked, all calls to datetime.datetime.now(), datetime.datetime.utcnow(), datetime.date.today(), time.time(), time.localtime(), time.gmtime(), and time.strftime() will return the time that has been frozen.

Decorator

from freezegun import freeze_time

@freeze_time("2012-01-14")
def test():
    assert datetime.datetime.now() == datetime.datetime(2012, 01, 14)

# Or class based

@freeze_time("2012-01-14")
class Tester(object):
    def test_the_class(self):
        assert datetime.datetime.now() == datetime.datetime(2012, 01, 14)

Context Manager

from freezegun import freeze_time

def test():
    assert datetime.datetime.now() != datetime.datetime(2012, 01, 14)
    with freeze_time("2012-01-14"):
        assert datetime.datetime.now() == datetime.datetime(2012, 01, 14)
    assert datetime.datetime.now() != datetime.datetime(2012, 01, 14)

Raw use

from freezegun import freeze_time

freezer = freeze_time("2012-01-14 12:00:01")
freezer.start()
assert datetime.datetime.now() == datetime.datetime(2012, 01, 14, 12, 00, 01)
freezer.stop()

Timezones

from freezegun import freeze_time

@freeze_time("2012-01-14 03:21:34", tz_offset=-4)
def test():
    assert datetime.datetime.utcnow() == datetime.datetime(2012, 01, 14, 03, 21, 34)
    assert datetime.datetime.now() == datetime.datetime(2012, 01, 13, 23, 21, 34)

    # datetime.date.today() uses local time
    assert datetime.date.today() == datetime.datetime(2012, 01, 13)

Nice inputs

FreezeGun uses dateutil behind the scenes so you can have nice-looking datetimes

@freeze_time("Jan 14th, 2012")
def test_nice_datetime():
    assert datetime.datetime.now() == datetime.datetime(2012, 01, 14)

Installation

To install FreezeGun, simply:

$ pip install freezegun

On Debian (Testing and Unstable) systems:

$ sudo apt-get install python-freezegun