'An acquired lease set to never expire is not removed from ``Leases``
map.'

def test_indefinite_lease_never_expires(self):

    leases = self.leases.acquire(self.now, self.dataset_id, self.node_id)
    self.assertIn(self.dataset_id, leases)
    now = (self.now + datetime.timedelta(seconds=self.lease_duration))
    leases = leases.expire(now)
    self.assertIn(self.dataset_id, leases)
