'Test that we don\'t blow up when trying to call week_start\'s
should_trigger on the first day of a trading environment.'

def test_NthTradingDayOfWeek_day_zero(self):

    rule = NthTradingDayOfWeek(0)
    rule.cal = self.cal
    first_open = self.cal.open_and_close_for_session(self.cal.all_sessions[0])
    self.assertTrue(first_open)
