Add @type_check_only to stub-only private classes in stdlib (#14512)

stdlib/unittest/case.pyi

@@ -7,7 +7,7 @@ from collections.abc import Callable, Container, Iterable, Mapping, Sequence, Se
 from contextlib import AbstractContextManager
 from re import Pattern
 from types import GenericAlias, TracebackType
-from typing import Any, AnyStr, Final, Generic, NoReturn, Protocol, SupportsAbs, SupportsRound, TypeVar, overload
+from typing import Any, AnyStr, Final, Generic, NoReturn, Protocol, SupportsAbs, SupportsRound, TypeVar, overload, type_check_only
 from typing_extensions import Never, ParamSpec, Self
 from unittest._log import _AssertLogsContext, _LoggingWatcher
 from warnings import WarningMessage
@@ -56,6 +56,7 @@ def skipUnless(condition: object, reason: str) -> Callable[[_FT], _FT]: ...
 class SkipTest(Exception):
     def __init__(self, reason: str) -> None: ...
 
+@type_check_only
 class _SupportsAbsAndDunderGE(SupportsDunderGE[Any], SupportsAbs[Any], Protocol): ...
 
 class TestCase:

stdlib/unittest/main.pyi

@@ -5,12 +5,13 @@ import unittest.result
 import unittest.suite
 from collections.abc import Iterable
 from types import ModuleType
-from typing import Any, Final, Protocol
+from typing import Any, Final, Protocol, type_check_only
 from typing_extensions import deprecated
 
 MAIN_EXAMPLES: Final[str]
 MODULE_EXAMPLES: Final[str]
 
+@type_check_only
 class _TestRunner(Protocol):
     def run(self, test: unittest.suite.TestSuite | unittest.case.TestCase, /) -> unittest.result.TestResult: ...
 

stdlib/unittest/mock.pyi

@@ -3,7 +3,7 @@ from _typeshed import MaybeNone
 from collections.abc import Awaitable, Callable, Coroutine, Iterable, Mapping, Sequence
 from contextlib import _GeneratorContextManager
 from types import TracebackType
-from typing import Any, ClassVar, Final, Generic, Literal, TypeVar, overload
+from typing import Any, ClassVar, Final, Generic, Literal, TypeVar, overload, type_check_only
 from typing_extensions import ParamSpec, Self, TypeAlias
 
 _T = TypeVar("_T")
@@ -262,6 +262,7 @@ class _patch(Generic[_T]):
 # This class does not exist at runtime, it's a hack to make this work:
 #     @patch("foo")
 #     def bar(..., mock: MagicMock) -> None: ...
+@type_check_only
 class _patch_pass_arg(_patch[_T]):
     @overload
     def __call__(self, func: _TT) -> _TT: ...
@@ -288,6 +289,7 @@ class _patch_dict:
 
 # This class does not exist at runtime, it's a hack to add methods to the
 # patch() function.
+@type_check_only
 class _patcher:
     TEST_PREFIX: str
     dict: type[_patch_dict]

stdlib/unittest/runner.pyi

@@ -4,15 +4,17 @@ import unittest.result
 import unittest.suite
 from _typeshed import SupportsFlush, SupportsWrite
 from collections.abc import Callable, Iterable
-from typing import Any, Generic, Protocol, TypeVar
+from typing import Any, Generic, Protocol, TypeVar, type_check_only
 from typing_extensions import Never, TypeAlias
 from warnings import _ActionKind
 
 _ResultClassType: TypeAlias = Callable[[_TextTestStream, bool, int], TextTestResult[Any]]
 
+@type_check_only
 class _SupportsWriteAndFlush(SupportsWrite[str], SupportsFlush, Protocol): ...
 
 # All methods used by unittest.runner.TextTestResult's stream
+@type_check_only
 class _TextTestStream(_SupportsWriteAndFlush, Protocol):
     def writeln(self, arg: str | None = None, /) -> None: ...