python单元测试模拟Popen和Popen.communicate

我试图编写一个python单元测试来执行子流程调用,因此我想模拟该调用。

我已经讨论了这些问题(没有用):

• Mocking a subprocess call in Python
• mocking subprocess.Popen
• mocking subprocess.Popen dependant on import style
• Mocking two functions with patch for a unit test

from subprocess import Popen, PIPE, STDOUT

def some_func():

  with Popen(some_list, stdout=PIPE, stderr=STDOUT) as process:

    stdout, stderr = process.communicate(timeout=timeout)

test.py

import mock

@mock.patch('benchmark.Popen.communicate')
@mock.patch('benchmark.Popen')
def test_some_func(self, mock_popen, mock_comm):

  mock_popen.return_value = 0
  mock_comm.return_value = ('output', 'error')

  foo = benchmark.some_func()

运行unittest时,我得到:

    stdout, stderr  = process.communicate(timeout=timeout)
ValueError: not enough values to unpack (expected 2, got 0)

看起来我不是在嘲笑 communicate

解决方案

我采纳了这些意见并提出了解决问题的建议:

import mock

@mock.patch('benchmark.Popen')
def test_some_func(self, mock_popen):

  process = mock_popen.return_value.__enter__.return_value
  process.returncode = 0
  process.communicate.return_value = (b'some output', b'some error')

  foo = benchmark.some_func()