Don't require IO for redirect_stdout (#14905)

Author: beauxq

stdlib/contextlib.pyi

@@ -4,7 +4,7 @@ from _typeshed import FileDescriptorOrPath, Unused
 from abc import ABC, abstractmethod
 from collections.abc import AsyncGenerator, AsyncIterator, Awaitable, Callable, Generator, Iterator
 from types import TracebackType
-from typing import IO, Any, Generic, Protocol, TypeVar, overload, runtime_checkable, type_check_only
+from typing import Any, Generic, Protocol, TypeVar, overload, runtime_checkable, type_check_only
 from typing_extensions import ParamSpec, Self, TypeAlias
 
 __all__ = [
@@ -30,7 +30,6 @@ if sys.version_info >= (3, 11):
 
 _T = TypeVar("_T")
 _T_co = TypeVar("_T_co", covariant=True)
-_T_io = TypeVar("_T_io", bound=IO[str] | None)
 _ExitT_co = TypeVar("_ExitT_co", covariant=True, bound=bool | None, default=bool | None)
 _F = TypeVar("_F", bound=Callable[..., Any])
 _G_co = TypeVar("_G_co", bound=Generator[Any, Any, Any] | AsyncGenerator[Any, Any], covariant=True)
@@ -141,14 +140,24 @@ class suppress(AbstractContextManager[None, bool]):
         self, exctype: type[BaseException] | None, excinst: BaseException | None, exctb: TracebackType | None
     ) -> bool: ...
 
-class _RedirectStream(AbstractContextManager[_T_io, None]):
-    def __init__(self, new_target: _T_io) -> None: ...
+# This is trying to describe what is needed for (most?) uses
+# of `redirect_stdout` and `redirect_stderr`.
+# https://github.com/python/typeshed/issues/14903
+@type_check_only
+class _SupportsRedirect(Protocol):
+    def write(self, s: str, /) -> int: ...
+    def flush(self) -> None: ...
+
+_SupportsRedirectT = TypeVar("_SupportsRedirectT", bound=_SupportsRedirect | None)
+
+class _RedirectStream(AbstractContextManager[_SupportsRedirectT, None]):
+    def __init__(self, new_target: _SupportsRedirectT) -> None: ...
     def __exit__(
         self, exctype: type[BaseException] | None, excinst: BaseException | None, exctb: TracebackType | None
     ) -> None: ...
 
-class redirect_stdout(_RedirectStream[_T_io]): ...
-class redirect_stderr(_RedirectStream[_T_io]): ...
+class redirect_stdout(_RedirectStream[_SupportsRedirectT]): ...
+class redirect_stderr(_RedirectStream[_SupportsRedirectT]): ...
 
 class _BaseExitStack(Generic[_ExitT_co]):
     def enter_context(self, cm: AbstractContextManager[_T, _ExitT_co]) -> _T: ...