单元测试 - Python如何测试HTTP客户端程序？

Question

打算写一个模拟HTTP客户端的程序（通过urlopen来发送和接收HTTP请求）。

需要写单元测试，初步打算使用unittest测试框架写测试用例。但是受具体环境限制，不能真正发送HTTP请求。
现在，退而求其次，写一个测试用例，不用发送请求并验证服务器返回的数据，只需要检查HTTP请求的头部和数据部分是否正确就好。
怎么写这种测试用例？
初步的想法是mock一个HTTP Server

Answer 1

OK, found unittest.mock.
unittest.mock was originally used to hook third-party modules (classes/functions) in unit tests (bypassing the original modules), but HTTP requests are also sent through a certain function and can also be used to simulate.

---

The following is an example:
main.py Program to be tested

from urllib.request import urlopen


def func():
    url_ip = 'http://ifconfig.me/ip'
    ip = None
    try:
        ip = urlopen(url_ip)
    except:
        pass
    return ip


if __name__ == '__main__':
    print(func())

test.py Test Case

import unittest
from unittest import mock

from main import func


class FuncTestCase(unittest.TestCase):
    @mock.patch('main.urlopen')
    def test_func(self, mock_open):
        mock_open.return_value = '127.0.0.1'
        #设置模拟函数的返回值
        result = func()
        #调用待测功能，但已经模拟了urlopen函数
        mock_open.assert_called_with('http://ifconfig.me/ip')
        #验证调用参数
        self.assertEqual(result, '127.0.0.1')
        #验证返回结果


if __name__ == '__main__':
    unittest.main()

Defect: If urlopen is called multiple times in func, the above code cannot be tested normally.
Update: You can replace the system function with your own function by setting the side_effect attribute of the mock object (but it is not very elegant).

Answer 2

You may need this.
http://docs.python-requests.org/en/latest/