[英]MagicMock's reset_mock not properly resetting sub-mock's side_effect
I have a long-lived patch on a class, whose made instance undergoes multiple batches of assertions.我在 class 上有一个长期存在的补丁,它的实例经历了多批断言。 Please see the below code snippet for the scenario.请参阅下面的代码片段以了解该场景。
It exposes (what I think is annoying) behavior in MagicMock.reset_mock
where it seemingly creates a new MagicMock
inside a sub- MagicMock
:它暴露了 MagicMock.reset_mock 中的(我认为很烦人的)行为,它似乎在子MagicMock.reset_mock
MagicMock
MagicMock
from unittest.mock import MagicMock
mock_cls = MagicMock()
mock_cls.return_value.method.side_effect = [5]
instance = mock_cls()
# Batch 1 of usage: uses side_effect
assert instance.method() == 5
mock_cls.reset_mock(return_value=True, side_effect=True)
# After this, mock_cls.return_value.method has a new id
# Batch 2 of usage: uses return_value
instance.return_value.method.return_value = 6
assert instance.method() == 6 # StopIteration
When run with Python 3.10.2, it raises a StopIteration
:当使用 Python 3.10.2 运行时,它会引发StopIteration
:
Traceback (most recent call last):
File "/path/to/code/play/quick_play.py", line 9, in <module>
assert instance.method() == 6
File "/path/to/.pyenv/versions/3.10.2/lib/python3.10/unittest/mock.py", line 1104, in __call__
return self._mock_call(*args, **kwargs)
File "/path/to/.pyenv/versions/3.10.2/lib/python3.10/unittest/mock.py", line 1108, in _mock_call
return self._execute_mock_call(*args, **kwargs)
File "/path/to/.pyenv/versions/3.10.2/lib/python3.10/unittest/mock.py", line 1165, in _execute_mock_call
result = next(effect)
StopIteration
Is it possible to use reset_mock
without creating new MagicMock
?是否可以在不创建新MagicMock
reset_mock
Alternately, how can I manually reset the side_effect
so the snippet runs?或者,如何手动重置side_effect
以便片段运行?
Aside在旁边
What is the visited=None
argument for in reset_mock
's signature? reset_mock
的签名中的visited=None
参数是什么? It's undocumented in the 3.10 docs , and here它在3.10 文档中没有记录,在这里
def reset_mock(self, visited=None,*, return_value=False, side_effect=False):
Sometimes in life, you answer your own question.有时在生活中,您会回答自己的问题。
Alternate to reset_mock
替代reset_mock
From the side_effect
docs来自side_effect
文档
If the function returns
DEFAULT
then the mock will return its normal value (from thereturn_value
).如果 function 返回DEFAULT
则模拟将返回其正常值(来自return_value
)。
from unittest.mock import MagicMock, DEFAULT
mock_cls = MagicMock()
mock_cls.return_value.method.side_effect = [5]
instance = mock_cls()
instance.method()
# Works, aligns with docs
mock_cls.return_value.method.side_effect = lambda: DEFAULT
instance.method() # <MagicMock name='mock().method()' ...>
# Alternately, this works too
mock_cls.return_value.method.side_effect = None
instance.method() # <MagicMock name='mock().method()' ...>
You can also find this used here and mentioned here .您还可以在此处找到使用的和在此处提及的。
Fixing My Snippet修复我的片段
There are two learnings here:这里有两个学习:
reset_mock
in favor of setting side_effect = None
放弃reset_mock
以支持设置side_effect = None
return_value
for the 2nd batch was used incorrectly第二批的return_value
使用不正确reset_mock
on the made instance
或者,我可以在制作的instance
上调用reset_mock
from unittest.mock import MagicMock
mock_cls = MagicMock()
mock_cls.return_value.method.side_effect = [5]
instance = mock_cls()
# Batch 1 of usage: uses side_effect
assert instance.method() == 5
mock_cls.return_value.method.side_effect = None
# instance.reset_mock(side_effect=True) # Also works
# Batch 2 of usage: uses return_value
instance.method.return_value = 6 # Correct
# instance.return_value.method.return_value = 6 # Original incorrect
assert instance.method() == 6
Future readers: stay hungry, stay foolish.未来的读者:保持饥饿,保持愚蠢。
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