def test_retain_listener():
m = lambda x, y: 0
l = Listener(on_data_available=m)
dp = DomainParticipant(0, listener=l)
l = dp.get_listener()
assert l.on_data_available == m
def test_get_listener():
dp = DomainParticipant(0, listener=Listener())
assert dp.get_listener()
