From 9a3078b825372f1774003c09eccb085cd43cb7a0 Mon Sep 17 00:00:00 2001
From: Aurel Wildfellner <201101774+aurelwildfellner@users.noreply.github.com>
Date: Thu, 5 Mar 2026 13:44:17 +0100
Subject: [PATCH] Add test_unclosed_interpreter_on_fork to cover gh-139759

---
 Lib/test/test_interpreters/test_stress.py | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/Lib/test/test_interpreters/test_stress.py b/Lib/test/test_interpreters/test_stress.py
index 6b40a536bd3c31..4e4e39714d8148 100644
--- a/Lib/test/test_interpreters/test_stress.py
+++ b/Lib/test/test_interpreters/test_stress.py
@@ -1,3 +1,4 @@
+import os
 import threading
 import unittest
 
@@ -83,6 +84,24 @@ def test_create_interpreter_no_memory(self):
             _testcapi.set_nomemory(0, 1)
             _interpreters.create()
 
+    @support.requires_fork()
+    def test_unclosed_interpreter_on_fork(self):
+        interp = interpreters.create()
+        interp.exec("pass")
+
+        fds = os.pipe()
+        pid = os.fork()
+
+        if pid == 0:
+            os.close(fds[0])
+            os.write(fds[1], b"OK")
+            os._exit(0)
+        else:
+            os.close(fds[1])
+            self.addCleanup(os.close, fds[0])
+            value = os.read(fds[0], 100)
+            self.assertEqual(value, b"OK")
+
 
 if __name__ == '__main__':
     # Test needs to be a package, so we can do relative imports.