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)