Unittest Patch only works on attributes, methods

Bug report

Bug description:

I am having an issue where the patch method from the unittest.mock module is only working when I patch attributes of imported modules in other files. I do not understand if this is an issue of my import patterns or a misunderstanding of how patching works. (I am importing the app code before the patch is able to run).

I devised a test to show how the functionality is confusing me:

In my app code I have the following code

    from datetime import date
    ...
    import boto3
    ...
    from common.functions import asodates2datetime
    from core.mixins.usecases import ASOUsecaseTools


    class foo:
        @staticmethod
        @ASOUsecaseTools.get_by_name
        def bar(self, relevant_date):
            client = boto3.client("s3")
            today = date.today()
            date = asodates2datetime(relevant_date)

And from my test code I can patch in the following way:

    @mock.patch("src.aoi.usecases.date")
    @mock.patch("src.aoi.usecases.ASOUsecaseTools.get_by_name")
    @mock.patch("src.aoi.usecases.asodates2datetime")
    @mock.patch("src.aoi.usecases.boto3.client")
    def test_foo_gets_bar(self, m_d, m_g, m_a, m_c):
        m_d.today.return_value = <date>
        m_d.side_effect = lambda *args, **kw: date(*args, **kw)
        # more patching of functions here

However, when the test is run, If I set a breakpoint in the bar function and check the value of the patched items, only the patched methods show up as MagicMock

    >>> boto3.client
        <MagicMock name='client...>
    >>> ASOUsecaseTools.get_by_name
        <MagicMock name='get_by_name...>
    >>> asodates2datetime
        <function asodates2datetime...>
    >>> date
        <class 'datetime.date'>

The thing that confuses me is that I am patching along with how the docs say to patch: https://docs.python.org/3/library/unittest.mock-examples.html#partial-mocking

Also the fact that patched methods work but classes and functions don't indicates that the import structure is not a problem because the imported methods would be overwritten in the same way as the imported classes. It also indicates that the import paths are not incorrect; as the only difference between the patches is the type of object they are patching.

My current workaround is using the freeze package to freeze the date, but I prefer using builtin packages if possible.

CPython versions tested on:

3.9

Operating systems tested on:

macOS

从 issue 中提供的 unittest.mock 复现代码开始，并将其 patch 目标与链接的 partial mocking 文档进行比较。在 CPython 3.9 上验证行为，然后确定观察到的差异究竟是可复现的解释器 bug，还是对 import/patching 的误解；一个具体的失败测试和预期行为将定义完成标准。