在 Python 中模拟子进程调用

问题描述

我有一个方法 (run_script) 想要测试.具体来说，我想测试对 subprocess.Popen 的调用是否发生.测试是否使用某些参数调用 subprocess.Popen 会更好.但是，当我运行测试时，我得到 TypeError: 'tuple' object is not callable.

I have a method (run_script) would like to test. Specifically I want to test that a call to subprocess.Popenoccurs. It would be even better to test that subprocess.Popen is called with certain parameters. When I run the test however I get TypeError: 'tuple' object is not callable.

如何测试我的方法以确保 subprocess 确实是使用模拟调用的?

How can I test my method to ensure that subprocess is actually being called using mocks?

@mock.patch('subprocess.Popen')
def run_script(file_path):
  process = subprocess.Popen(['myscript', -M, file_path], stdout=subprocess.PIPE)
  output,err = process.communicate()
  return process.returncode

def test_run_script(self, mock_subproc_popen):
  mock_subproc_popen.return_value = mock.Mock(communicate=('ouput','error'), returncode=0)
  am.account_manager("path")
  self.assertTrue(mock_subproc_popen.called)

推荐答案

你在 run_script 函数上使用补丁装饰器对我来说似乎很不寻常，因为你没有在那里传递模拟参数.

It seems unusual to me that you use the patch decorator over the run_script function, since you don't pass a mock argument there.

这个怎么样:

def run_script(file_path):
  process = subprocess.Popen(['myscript', -M, file_path], stdout=subprocess.PIPE)
  output,err = process.communicate()
  return process.returncode

@mock.patch('subprocess.Popen')
def test_run_script(self, mock_subproc_popen):
  process_mock = mock.Mock()
  attrs = {'communicate.return_value': ('output', 'error')}
  process_mock.configure_mock(**attrs)
  mock_subproc_popen.return_value = process_mock 
  am.account_manager("path") # this calls run_script somewhere, is that right?
  self.assertTrue(mock_subproc_popen.called)

现在，您模拟的 subprocess.Popen 似乎返回一个元组，导致 process.communicate() 引发 TypeError: 'tuple' object is not callable..所以最重要的是将mock_subproc_popen上的return_value弄的恰到好处.

Right now, your mocked subprocess.Popen seems to return a tuple, causeing process.communicate() to raise TypeError: 'tuple' object is not callable.. Therefore it's most important to get the return_value on mock_subproc_popen just right.

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