Tell typecheckers that Promise is a context manager

bitprophet · bitprophet · commit 9b086f4e511c · 2026-04-06T18:32:02.000-04:00
diff --git a/invoke/runners.py b/invoke/runners.py
@@ -6,6 +6,7 @@
 import sys
 import threading
 import time
+from contextlib import AbstractContextManager
 from subprocess import PIPE, Popen
 from types import TracebackType
 from typing import (
@@ -1614,7 +1615,7 @@ def tail(self, stream: str, count: int = 10) -> str:
         return "\n\n" + "\n".join(getattr(self, stream).splitlines()[-count:])
 
 
-class Promise(Result):
+class Promise(Result, AbstractContextManager):
     """
     A promise of some future `Result`, yielded from asynchronous execution.
 
diff --git a/tests/runners.py b/tests/runners.py
@@ -6,6 +6,7 @@
 import termios
 import threading
 import types
+from contextlib import AbstractContextManager
 from io import BytesIO, StringIO
 from itertools import chain, repeat
 from unittest.mock import Mock, call, patch
@@ -1825,6 +1826,10 @@ def works_for_stderr_too(self):
 
 
 class Promise_:
+    def explicitly_inherits_from_abstract_base_class(self) -> None:
+        # Supports improved downstream typechecking.
+        assert AbstractContextManager in Promise.__mro__
+
     def exposes_read_only_run_params(self):
         runner = _runner()
         promise = runner.run(
