context_management: add a type stub override to fix typing

.pre-commit-config.yaml

@@ -51,6 +51,8 @@ repos:
         args: [--show-error-codes, --ignore-missing-imports]
         additional_dependencies:
           [types-setuptools, types-requests, types-python-dateutil]
+          # This file is overridden by a type stub
+        exclude: "specfile/context_management.py"
   - repo: https://github.com/teemtee/tmt.git
     rev: 1.41.0
     hooks:

specfile/context_management.pyi

@@ -0,0 +1,25 @@
+# Copyright Contributors to the Packit project.
+# SPDX-License-Identifier: MIT
+
+import contextlib
+from collections.abc import Iterator
+from typing import Callable, Generator, ParamSpec, TypeVar
+
+_T_co = TypeVar("_T_co", covariant=True)
+_P = ParamSpec("_P")
+
+@contextlib.contextmanager
+def capture_stderr() -> Generator[list[bytes], None, None]: ...
+
+class GeneratorContextManager(contextlib._GeneratorContextManager[_T_co]):
+    def __init__(self, function: Callable[..., _T_co]) -> None: ...
+    def __del__(self) -> None: ...
+    @property
+    def content(self) -> _T_co: ...
+
+# Instead of the original descriptor class, tell the type checker to treat
+# ContextManager as a simple decorator function which is something that it
+# understands.
+def ContextManager(
+    func: Callable[_P, Iterator[_T_co]],
+) -> Callable[_P, GeneratorContextManager[_T_co]]: ...