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A fast alternative to freezegun that wraps libfaketime.

Project description

python-libfaketime is a wrapper of libfaketime for python.

import datetime

from libfaketime import fake_time, reexec_if_needed

# libfaketime needs to be preloaded by the dynamic linker.
# This will exec the same command, but with the proper environment variables set.
# Or you can skip running this and manually manage your env (see get_reload_information()).

def get_tomorrow():
    return + datetime.timedelta(days=1)

@fake_time('2014-01-01 00:00:00')
def test_get_tomorrow():
    assert get_tomorrow() ==, 1, 2)

It serves as a fast drop-in replacement for freezegun. Here’s the output of a totally unscientific benchmark on my laptop:

$ python
re-exec with libfaketime dependencies
timing 1000 executions of <class 'libfaketime.fake_time'>
0.021755 seconds

$ python freezegun
timing 1000 executions of <function freeze_time at 0x10aaa1140>
6.561472 seconds

Some brief details:

  • linux and osx
  • microsecond resolution
  • accepts datetimes and strings that can be parsed by dateutil
  • not threadsafe
  • will break profiling. A workaround: use libfaketime.{begin, end}_callback to disable/enable your profiler.

To install: pip install libfaketime.


Semantic versioning is used.


released 2015-09-11


released 2015-06-23

  • add global start/stop callbacks


released 2015-03-28

  • initial packaged release

Project details

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