'L{MXCalculator.getMX} returns the MX record with the lowest preference
which is not also marked as bad.'

def test_badExchangeExcluded(self):

    domain = 'example.com'
    good = 'good.example.com'
    bad = 'bad.example.com'
    records = [RRHeader(name=domain, type=Record_MX.TYPE, payload=Record_MX(0, bad)), RRHeader(name=domain, type=Record_MX.TYPE, payload=Record_MX(1, good))]
    self.mx.markBad(bad)
    return self._exchangeTest(domain, records, good)
