bpo-31786: Make functions in the select module blocking when timeout is a small negative value. (#4003)
diff --git a/Lib/test/test_poll.py b/Lib/test/test_poll.py
index 16c2d2e..028dd2d 100644
--- a/Lib/test/test_poll.py
+++ b/Lib/test/test_poll.py
@@ -204,6 +204,28 @@
os.write(w, b'spam')
t.join()
+ @unittest.skipUnless(threading, 'Threading required for this test.')
+ @reap_threads
+ def test_poll_blocks_with_negative_ms(self):
+ for timeout_ms in [None, -1, -1.0, -0.1, -1e-100]:
+ # Create two file descriptors. This will be used to unlock
+ # the blocking call to poll.poll inside the thread
+ r, w = os.pipe()
+ pollster = select.poll()
+ pollster.register(r, select.POLLIN)
+
+ poll_thread = threading.Thread(target=pollster.poll, args=(timeout_ms,))
+ poll_thread.start()
+ poll_thread.join(timeout=0.1)
+ self.assertTrue(poll_thread.is_alive())
+
+ # Write to the pipe so pollster.poll unblocks and the thread ends.
+ os.write(w, b'spam')
+ poll_thread.join()
+ self.assertFalse(poll_thread.is_alive())
+ os.close(r)
+ os.close(w)
+
def test_main():
run_unittest(PollTests)