def test_start_of_period(self):
year, month, day = 2010, 8, 17
time = date(year, month, day)
start_day = date(year, month, day)
start_week = date(year, month, 16)
start_month = date(year, month, 1)
adp = DataPoint()
self.failUnlessEqual(adp._start_of_period("D",time), start_day)
self.failUnlessEqual(adp._start_of_period("W",time), start_week)
self.failUnlessEqual(adp._start_of_period("M",time), start_month)
