如何在python中模拟套接字库的recvfrom？

Question

我在python（sniffer.py）中有以下代码，它会嗅探数据包，

import socket 

def get_packet():

    #create an INET, raw socket
    s = socket.socket(socket.AF_INET, socket.SOCK_RAW, socket.IPPROTO_TCP)
    #current_interval and conf_interval are read here. where current_interval is a difference of time.time and the time at which program began. and conf_interval is pre-configured interval
    # receive a packet
    while current_interval < conf_interval:
        pkt = s.recvfrom(65565)
        process(pkt)

if __name__ == '__main__':
    get_packet()

我正在为这段代码编写单元测试，如何模拟recvfrom函数返回虚拟数据包？ 这似乎不像我预期的那样有效，

with patch('sniffer.socket.socket.recvfrom') as m_recvfrom:
    m_recvfrom.return_value = dummy_pkt

这只是给了我一个模拟对象，我无法访问dummy_pkt。 我如何使这项工作？

谢谢！