无法模拟模拟对象的方法？ call_count 在pytest中为0

Question

我在文件myfile.py中有以下函数：

#myfile.py
import psutil
class RunnableObject:
    def run(self):
        parent = psutil.Process()
        print(parent)
        children = parent.children(recursive=True)
        print(children)

然后我有一个单元测试，其中 runnable_object 是我使用 pytest fixture 设置的 RunnableObject class 的一个实例。

@patch("myfile.psutil")
def test_run_post_request(self, psutil_, runnable_object):
        runnable_object.run()
        assert psutil_.Process.call_count == 1
        assert psutil_.Process.children.call_count == 1

当我运行我的测试但是我得到以下错误：

       assert psutil_.Process.call_count == 1
>       assert psutil_.Process.children.call_count == 1
E       assert 0 == 1
E         +0
E         -1
     -1

tests/unit/test_experiment.py:1651: AssertionError

我的标准输出：

<MagicMock name='psutil.Process()' id='3001903696'>
<MagicMock name='psutil.Process().children()' id='3000968624'>

我也尝试过使用 @patch.object(psutil.Process, "children") 以及 @patch("myfile.psutil.Process") 和 @patch("myfile.psutil.Process.children") 但是这给了我同样的问题。

Answer 1

children 是 psutil.Process() 的 return 值的属性。不是 Process 方法的属性。

所以正确的说法是：

test_myfile.py:

from unittest import TestCase
import unittest
from unittest.mock import patch
from myfile import RunnableObject


class TestRunnableObject(TestCase):
    @patch("myfile.psutil")
    def test_run_post_request(self, psutil_):
        runnable_object = RunnableObject()
        runnable_object.run()
        assert psutil_.Process.call_count == 1
        assert psutil_.Process().children.call_count == 1


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

测试结果：

<MagicMock name='psutil.Process()' id='4394128192'>
<MagicMock name='psutil.Process().children()' id='4394180912'>
.
----------------------------------------------------------------------
Ran 1 test in 0.002s

OK
Name                                        Stmts   Miss  Cover   Missing
-------------------------------------------------------------------------
src/Whosebug/67362647/myfile.py            7      0   100%
src/Whosebug/67362647/test_myfile.py      13      0   100%
-------------------------------------------------------------------------
TOTAL                                          20      0   100%

无法模拟模拟对象的方法？ call_count 在pytest中为0

Cannot mock method of mocked object? call_count is 0 in pytest

python

unit-testing

mocking

pytest

psutil