Feat: Fix Windows handle invalid error with subprocess.Popen under capture (Python 3.14)

src/_pytest/capture.py

@@ -516,10 +516,32 @@ def _assert_state(self, op: str, states: tuple[str, ...]) -> None:
             )
         )
 
+    def _sync_win32_stdhandle(self, targetfd: int) -> None:
+        if sys.platform != "win32":
+            return
+
+        import ctypes
+        import msvcrt
+
+        fd_to_std = {
+            0: -10,  # STD_INPUT_HANDLE
+            1: -11,  # STD_OUTPUT_HANDLE
+            2: -12,  # STD_ERROR_HANDLE
+        }
+
+        std_id = fd_to_std.get(targetfd)
+        if std_id is None:
+            return
+
+        handle = msvcrt.get_osfhandle(targetfd)
+        ctypes.windll.kernel32.SetStdHandle(std_id, handle)
+
     def start(self) -> None:
         """Start capturing on targetfd using memorized tmpfile."""
         self._assert_state("start", ("initialized",))
         os.dup2(self.tmpfile.fileno(), self.targetfd)
+
+        self._sync_win32_stdhandle(self.targetfd)
         self.syscapture.start()
         self._state = "started"
 
@@ -530,6 +552,7 @@ def done(self) -> None:
         if self._state == "done":
             return
         os.dup2(self.targetfd_save, self.targetfd)
+        self._sync_win32_stdhandle(self.targetfd)
         os.close(self.targetfd_save)
         if self.targetfd_invalid is not None:
             if self.targetfd_invalid != self.targetfd:
@@ -545,6 +568,7 @@ def suspend(self) -> None:
             return
         self.syscapture.suspend()
         os.dup2(self.targetfd_save, self.targetfd)
+        self._sync_win32_stdhandle(self.targetfd)
         self._state = "suspended"
 
     def resume(self) -> None:
@@ -553,6 +577,7 @@ def resume(self) -> None:
             return
         self.syscapture.resume()
         os.dup2(self.tmpfile.fileno(), self.targetfd)
+        self._sync_win32_stdhandle(self.targetfd)
         self._state = "started"