def test_least_connections():
backend1 = Server('localhost:8081')
backend1.open_connections = 10
backend2 = Server('localhost:8082')
backend2.open_connections = 5
backend3 = Server('localhost:8083')
backend3.open_connections = 2
servers = [backend1, backend2, backend3]
result = least_connections(servers)
assert result == backend3
def test_least_connections_empty_list():
result = least_connections([])
assert result == None