python unittest - 如何保留已转换为 Mock object 的函数的副作用？

Question

I want to count the number of times that a function is called, python patch has been recommended allowing me to call call_count and things like assert_not_called to verify just that.

My problem is that I want the function to perform just as it did, as its function is required for the tests and it's on dynamic data so I cannot simply hardcode the result.

with patch.object(shutil, 'copy') as mm:

  do_some_things()

  mm.assert_not_called()

For do_some_things() to work correctly, shutil.copy still needs to perform its original role

Answer 1

I would suggest just using patch not patch.object . You can still accomplish all you want with that. I don't having anything in ~/test

from unittest import TestCase
from unittest.mock import patch

from shutil import copy

def do_some_things(src, dst):
    copy(src, dst)


class TestDoSomething(TestCase):

    def test_do_somethings(self):
        with patch('test_do_some_things.copy') as mm:
            do_some_things('~/test.txt', '~/test/test.txt')
        mm.called_once()
        print(mm.call_count)