unittest.mock: use ParamSpec in patch (#10325)

Fixes #10324

stdlib/unittest/mock.pyi

@@ -3,13 +3,14 @@ from collections.abc import Awaitable, Callable, Coroutine, Iterable, Mapping, S
 from contextlib import _GeneratorContextManager
 from types import TracebackType
 from typing import Any, Generic, TypeVar, overload
-from typing_extensions import Final, Literal, Self, TypeAlias
+from typing_extensions import Final, Literal, ParamSpec, Self, TypeAlias
 
 _T = TypeVar("_T")
 _TT = TypeVar("_TT", bound=type[Any])
 _R = TypeVar("_R")
 _F = TypeVar("_F", bound=Callable[..., Any])
 _AF = TypeVar("_AF", bound=Callable[..., Coroutine[Any, Any, Any]])
+_P = ParamSpec("_P")
 
 if sys.version_info >= (3, 8):
     __all__ = (
@@ -234,7 +235,7 @@ class _patch(Generic[_T]):
     @overload
     def __call__(self, func: _TT) -> _TT: ...
     @overload
-    def __call__(self, func: Callable[..., _R]) -> Callable[..., _R]: ...
+    def __call__(self, func: Callable[_P, _R]) -> Callable[_P, _R]: ...
     if sys.version_info >= (3, 8):
         def decoration_helper(
             self, patched: _patch[Any], args: Sequence[Any], keywargs: Any

test_cases/stdlib/check_unittest.py

@@ -1,9 +1,12 @@
 from __future__ import annotations
 
 import unittest
+from collections.abc import Callable
 from datetime import datetime, timedelta
 from decimal import Decimal
 from fractions import Fraction
+from typing_extensions import assert_type
+from unittest.mock import Mock, patch
 
 case = unittest.TestCase()
 
@@ -86,3 +89,29 @@ case.assertGreater(datetime(1999, 1, 2), 1)  # type: ignore
 case.assertGreater(Spam(), Eggs())  # type: ignore
 case.assertGreater(Ham(), Bacon())  # type: ignore
 case.assertGreater(Bacon(), Ham())  # type: ignore
+
+###
+# Tests for mock.patch
+###
+
+
+@patch("sys.exit", new=Mock())
+def f(i: int) -> str:
+    return "asdf"
+
+
+assert_type(f(1), str)
+f("a")  # type: ignore
+
+
+@patch("sys.exit", new=Mock())
+class TestXYZ(unittest.TestCase):
+    attr: int = 5
+
+    @staticmethod
+    def method() -> int:
+        return 123
+
+
+assert_type(TestXYZ.attr, int)
+assert_type(TestXYZ.method, Callable[[], int])

tests/utils.py

@@ -111,12 +111,12 @@ def testcase_dir_from_package_name(package_name: str) -> Path:
 
 
 def get_all_testcase_directories() -> list[PackageInfo]:
-    testcase_directories = [PackageInfo("stdlib", Path("test_cases"))]
+    testcase_directories: list[PackageInfo] = []
     for package_name in os.listdir("stubs"):
         potential_testcase_dir = testcase_dir_from_package_name(package_name)
         if potential_testcase_dir.is_dir():
             testcase_directories.append(PackageInfo(package_name, potential_testcase_dir))
-    return sorted(testcase_directories)
+    return [PackageInfo("stdlib", Path("test_cases"))] + sorted(testcase_directories)
 
 
 # ====================================================================