Skip to main content

Various utilities related to date and time for testing purposes.

Project description

This package allows to cheat with current time in tests. It has initially been used in OpenERP to test workflows spanning over a long period of time.

Currently it mainly provides a datetime.set_now() method to fake the current time.

Usage

Before anything, the package must be imported in order to replace the regular datetime module with the modified one:

>>> import anybox.testing.datetime
>>> from datetime import datetime
>>> import time

Let’s keep the real value of now around:

>>> start = datetime.now()
>>> start_t = time.time()

Then you can change the current time:

>>> datetime.set_now(datetime(2001, 01, 01, 3, 57, 0))
>>> datetime.now()
datetime(2001, 1, 1, 3, 57)
>>> datetime.today()
datetime(2001, 1, 1, 3, 57)

The time module goes along:

>>> datetime.fromtimestamp(time.time())
datetime(2001, 1, 1, 3, 57)

Note that you can expect a few microseconds difference (not displayed here because datetime.fromtimestamp ignores them).

Don’t forget afterwards to get back to the regular system clock, otherwise many pieces of code might get very suprised if the system clock looks as if it’s frozen:

>>> datetime.real_now()

Now let’s check it worked:

>>> now = datetime.now()
>>> now > start
True
>>> from datetime import timedelta
>>> now - start < timedelta(0, 0, 10000) # 10 ms
True

And with the time module:

>>> now_t = time.time()
>>> now_t > start_t
True
>>> now_t - start_t < 0.01 # 10 ms again
True

Other constructors are still available (this is a non regression test):

>>> import datetime
>>> datetime.time(3, 57, 0)
datetime.time(3, 57)
>>> datetime.datetime(2013, 1, 1, 3, 57, 0)
datetime(2013, 1, 1, 3, 57)
>>> datetime.date(2013, 1, 1)
datetime.date(2013, 1, 1)

Behind the hood

Our replacement class is the one loaded from the datetime module, but instances of the original datetime class behave exactly as instances of our datetime.datetime. This is needed because most computational methods, actually return an object of the original datetime class. This works with python >= 2.6 only.

First let’s check that our class is a subclass of the original one. If this fails, this test does not mean anything anymore:

>>> datetime.datetime is datetime.original_datetime
False
>>> issubclass(datetime.datetime, datetime.original_datetime)
True

Then let’s demonstrate the behaviour:

>>> odt = datetime.original_datetime(2012, 1, 1)
>>> isinstance(odt, datetime.datetime)
True
>>> issubclass(datetime.original_datetime, datetime.datetime)
True

We’ll need a tzinfo subclass from now on.

>>> from datetime import tzinfo
>>> class mytzinfo(tzinfo):
...     def utcoffset(self, dt):
...         return timedelta(hours=2)
...     def dst(self, dt):
...         return timedelta(0)

Compatibility

Over the lifespan of this development toolkit module, we’ve had to ensure compatibility with several subsystems

SQLite

Also, sqlite3 does recognize our datetime and date classes as if they were the original ones:

>>> import sqlite3
>>> cnx = sqlite3.connect(':memory:')
>>> cr = cnx.cursor()
>>> cr = cr.execute("CREATE TABLE dates (dt text, d text)")
>>> dt = datetime.datetime(2013, 1, 25, 12, 34, 0)
>>> d = datetime.date(2013, 4, 7)
>>> cr = cr.execute("INSERT INTO dates VALUES (?, ?)", (dt, d))
>>> cr = cr.execute("SELECT dt, d from dates")
>>> cr.fetchall()
[(u'2013-01-25 12:34:00', u'2013-04-07')]

Now let’s try this again with the original ones:

>>> dt = datetime.datetime.now()
>>> isinstance(dt, datetime.original_datetime)
True
>>> d = datetime.date.today()
>>> cr = cr.execute("INSERT INTO dates VALUES (?, ?)", (dt, d))
>>> cr = cr.execute("SELECT dt, d from dates")
>>> res = cr.fetchall() # can't check the value, it changes a lot !

Test

This README is also a doctest. To it and other doctests for this package, simply do:

nosetests --with-doctest --doctest-extension=txt

Changes

0.4.2 (2013-06-11)

  • A few improvements in the doc

0.4.1 (2013-04-24)

  • #3: fixed compatibility problem with sqlite3 (spotted via IPython/IPdb)

0.3.1 (2012-11-28)

  • #1: tested code using time zone optional arg of now() doesn’t break any more (no real time zone support, though)

0.3 (2012-11-23)

  • Fixed the problem that datetime objects generated from computations used to fail isinstance tests.

0.2.1 (2012-11-22)

  • Fixed issue with datetime.time masking

0.1 (2012-07-15)

  • initial version

Project details


Download files

Download the file for your platform. If you're not sure which to choose, learn more about installing packages.

Source Distribution

anybox.testing.datetime-0.4.2.tar.gz (5.8 kB view hashes)

Uploaded Source

Supported by

AWS AWS Cloud computing and Security Sponsor Datadog Datadog Monitoring Fastly Fastly CDN Google Google Download Analytics Microsoft Microsoft PSF Sponsor Pingdom Pingdom Monitoring Sentry Sentry Error logging StatusPage StatusPage Status page