我尝试在python中使用超时异常模拟 socket 并拥有这个小测试程序：
#!/usr/bin/env python3
import socket
class SocketToutClass():
def socket_timeout(self):
"""Set up UDP socket with timeout"""
sock = socket.socket(socket.AF_INET, socket.SOCK_DGRAM, socket.IPPROTO_UDP)
sock.settimeout(2)
cnt = sock.sendto(b'hello world', ('239.255.255.250', 1900))
print('sent', cnt, 'bytes')
try:
while True:
data = sock.recv(4096)
print(data.decode(), end='')
except socket.timeout:
print('timed out')
except KeyboardInterrupt:
pass
if __name__ == "__main__":
oTout = SocketToutClass()
oTout.socket_timeout()
运行它我得到这个输出：
~$ python3 socket_tout.py
sent 11 bytes
timed out
~$
我读了Raising exceptions with mocks：
一个有用的属性是side_effect . 如果将其设置为异常类或实例，则在调用mock时将引发异常 .
现在我模拟它包括超时异常：
#!/usr/bin/env python3
import unittest
from unittest.mock import patch
from socket_tout import SocketToutClass
class socket_timeoutTestCase(unittest.TestCase):
@patch('socket_tout.socket.socket') # Patch the class
def test_socket_timeout(self, mock_socket):
oMock_socket = mock_socket.return_value # we want the instance
# set up our service and instantiate it
oMock_socket.sendto.return_value = 11
oMock_socket.recv.return_value = b'data\r\n'
oMock_socket(side_effect=Exception('timeout'))
oTout = SocketToutClass()
oTout.socket_timeout()
运行测试我得到无限输出而没有超时：
~$ python3 -m unittest socket_toutTest.py
sent 11 bytes
data
data
data
...
我做错了什么？为什么超时异常不会引发？