datetime_hack.py

# DANGERZONE!! This is globally overriding default python behavior. Caveat emptor
# FAKE_DATE=1999-01-01 python
# >>> import datetime_hack, datetime
# >>> datetime.date.today()
# 1999-01-01


import datetime
import os

class Datetime(datetime.datetime):
    @classmethod
    def now(cls,*args,**kwargs):
        dt = super(Datetime,cls).now(*args,**kwargs)
        if os.environ.get("FAKE_DATE"):
            y,m,d = os.environ['FAKE_DATE'].split("-")
            dt = dt.replace(year=int(y),month=int(m),day=int(d))
        if os.environ.get("FAKE_TIME"):
            h,m = os.environ.FAKE_TIME.split(':')
            dt = dt.replace(hour=int(h),minute=int(m))
        return dt

class Date(datetime.date):
    @classmethod
    def today(cls,*args,**kwargs):
        if os.environ.get("FAKE_DATE"):
            y,m,d = os.environ['FAKE_DATE'].split("-")
            return cls(year=int(y),month=int(m),day=int(d))
        return super(Date,cls).today(*args,**kwargs)

datetime.datetime = Datetime
datetime.date = Date