zc.time

zc.time provides a single point of creating datetime objects with the current time. It is easily swappable with a test method without having to monkeypatch the standard datetime classes.

>>> import time
>>> import zc.time

>>> now = zc.time.now()

>>> type(now)
<type 'datetime.datetime'>

It also defaults to UTC, which the vanilla datetime does not.

>>> now.tzinfo
<UTC>

There’s also a utcnow() function, which returns the naive UTC time corresponding to the now() function’s return value. This provides a utcnow() implementation that’s similarly affected by replacing the now() function:

>>> now = zc.time.utcnow()

>>> type(now)
<type 'datetime.datetime'>

>>> now.tzinfo

This relationship holds even if now() is replaced (not recommended):

>>> import datetime
>>> import pytz

>>> t = datetime.datetime(2010, 4, 1, 10, 50, 30, 2345, pytz.UTC)
>>> old_now = zc.time.now

>>> zc.time.now = lambda: t

>>> zc.time.now()
datetime.datetime(2010, 4, 1, 10, 50, 30, 2345, tzinfo=<UTC>)
>>> zc.time.utcnow()
datetime.datetime(2010, 4, 1, 10, 50, 30, 2345)

The reset() function provided cleans up modifications made to control the time:

>>> zc.time.reset()
>>> zc.time.now is old_now
True

A set_now() function is provided that takes a datetime, and causes now() and utcnow() to pretend that’s the real time. The time passed in can be in any time zone; naive times are converted to UTC using pytz.UTC.localize:

>>> zc.time.set_now(t)

>>> zc.time.now()
datetime.datetime(2010, 4, 1, 10, 50, 30, 2345, tzinfo=<UTC>)
>>> zc.time.utcnow()
datetime.datetime(2010, 4, 1, 10, 50, 30, 2345)
>>> time.time()
1270137030.002345

>>> naive = datetime.datetime(2010, 4, 1, 12, 27, 3, 5432)

>>> zc.time.set_now(naive)

>>> zc.time.now()
datetime.datetime(2010, 4, 1, 12, 27, 3, 5432, tzinfo=<UTC>)
>>> zc.time.utcnow()
datetime.datetime(2010, 4, 1, 12, 27, 3, 5432)
>>> time.time()
1270142823.005432

>>> t = datetime.datetime(2010, 4, 1, 11, 17, 3, 5432,
...                       pytz.timezone("US/Eastern"))

>>> zc.time.set_now(t)

>>> zc.time.now()
datetime.datetime(2010, 4, 1, 16, 17, 3, 5432, tzinfo=<UTC>)
>>> zc.time.utcnow()
datetime.datetime(2010, 4, 1, 16, 17, 3, 5432)
>>> time.time()
1270156623.005432

To move forward in time, simply use set_now() again:

>>> zc.time.set_now(t + datetime.timedelta(hours=1))

>>> zc.time.now()
datetime.datetime(2010, 4, 1, 17, 17, 3, 5432, tzinfo=<UTC>)
>>> zc.time.utcnow()
datetime.datetime(2010, 4, 1, 17, 17, 3, 5432)
>>> time.time()
1270160223.005432

If an application sleeps using time.sleep, that’ll be reflected in the times reported:

>>> import time

>>> time.sleep(0.25)
>>> zc.time.now()
datetime.datetime(2010, 4, 1, 17, 17, 3, 255432, tzinfo=<UTC>)
>>> zc.time.utcnow()
datetime.datetime(2010, 4, 1, 17, 17, 3, 255432)
>>> time.time()
1270160223.255432

The reported time will be updated by the exact delay requested of the time.sleep call, rather than by the actual delay.

The reset() function is used to clean up after this as well:

>>> zc.time.reset()

The reset() is registered as a general cleanup handler if zope.testing is available. This is generally not sufficient for functional tests, which will need to call reset themselves.