def nyse_add_and_substract(self):
ans = DateUtils.nyse_add(datetime(2009, 4, 13), 5)
self.assertEquals(ans, datetime(2009, 4, 20))
ans = DateUtils.nyse_substract(datetime(2009, 4, 13), 5)
self.assertEquals(ans, datetime(2009, 4, 3))
ans = DateUtils.nyse_add(datetime(1990, 10, 1), 7)
self.assertEquals(ans, datetime(1990, 10, 10))
ans = DateUtils.nyse_substract(datetime(1990, 10, 1), 3)
self.assertEquals(ans, datetime(1990, 9, 26))
