'Fail if we try to failover multiple backends in the same request.'

@ddt.data(('host1', None), (None, 'mycluster'))
@ddt.unpack
def test_failover_api_fail_multiple_results(self, host, cluster):

    rep_field = fields.ReplicationStatus
    clusters = [objects.Cluster(self.context, name='mycluster@backend1', replication_status=rep_field.ENABLED, binary=constants.VOLUME_BINARY), objects.Cluster(self.context, name='mycluster@backend2', replication_status=rep_field.ENABLED, binary=constants.VOLUME_BINARY)]
    clusters[0].create()
    clusters[1].create()
    services = [objects.Service(self.context, host='host1@backend1', cluster_name=clusters[0].name, replication_status=rep_field.ENABLED, binary=constants.VOLUME_BINARY), objects.Service(self.context, host='host1@backend2', cluster_name=clusters[1].name, replication_status=rep_field.ENABLED, binary=constants.VOLUME_BINARY)]
    services[0].create()
    services[1].create()
    self.assertRaises(exception.Invalid, self.volume_api.failover, self.context, host, cluster)
