1. ollyc
  2. frozendate

Overview

Frozendate: stop time for your tests

Frozendate suspends time while your tests run.

Frozendate mocks datetime.datetime and datetime.date to provide known times when testing.

Usage

import frozendate

with frozendate.freeze(1999, 1, 1):
    party_like_its_1999()

# freeze relative freezes time relative to the current date...
with freeze_relative(days=-1):
    assert all_my_troubles_seemed_so_far_away()

with freeze(1999, 12, 31):
    # ...or relative to the previous freeze
    with freeze_relative(days=1):
        print "happy new year!"

Normally time doesn't actually stop when you use freeze – it just starts again from the fixed point you specify, eg:

>>> import frozendate
>>> import datetime
>>> with frozendate.freeze(2000, 1, 1):
...     print datetime.now().replace(microsecond=0)
...     time.sleep(1)
...     print datetime.now().replace(microsecond=0)
...
2000-01-01 00:00:00
2000-01-01 00:00:01

But you can always get the same value back if you pass hard=True:

>>> with frozendate.freeze(2000, 1, 1, hard=True):
...     print datetime.now().replace(microsecond=0)
...     time.sleep(1)
...     print datetime.now().replace(microsecond=0)
...
2000-01-01 00:00:00
2000-01-01 00:00:00

Instead of a context manager there are also regular patch and unpatch functions. These are useful in test case setup/teardown methods:

def setUp(self):
    frozendate.patch(2000, 1, 1)

def tearDown(self):
    frozendate.unpatch()

When you call freeze or patch, it freezes time for all modules found in sys.modules. Sometimes you want to restrict to a few named modules:

frozendate.freeze(modules=['mypackage.mymodule'])

Or patch everything, but exclude a few modules that need the real datetime still:

frozendate.freeze(dontpatch=['somemodule', 'someotherpackage'])