`autospec` doesn't work with lazy-imported symbols

[zsol]

Bug report

Bug description:

unittest.mock.patch(target, autospec=True) reads unresolved lazy-import bindings directly from target.__dict__ and autospecs the LazyImportType proxy instead of the imported symbol.

from unittest.mock import patch

lazy from json import dumps

with patch("__main__.dumps", autospec=True) as mock_dumps:
    mock_dumps({})

On CPython main (9d231cbc937f as of now), this raises:

TypeError: 'NonCallableMagicMock' object is not callable

Resolving dumps before patching works. This also affects patch.object, spec=True, and spec_set=True.

A practical example is concurrent.futures.ThreadPoolExecutor, which now uses an explicit lazy import: existing tests such as this one patch it with autospec=True and encounter the same issue.

CPython versions tested on:

CPython main branch

Operating systems tested on:

Linux, macOS, Windows

Linked PRs

• gh-153888: autospec doesn't work with lazy-imported symbols #153977
• gh-153888: Resolve lazy imports before using them as a mock spec #157768
• [3.15] gh-153888: Resolve lazy imports before using them as a mock spec (GH-157768) #158396

[brittanyrey]

The linked PR has fallen stale for the last 2 months. With the 3.15 final cut coming up, I'm putting up a new PR which also addresses the open comments left on the original PR. #157768