Issue #16230: Fix a crash in select.select() when one the lists changes size while iterated on.

Patch by Serhiy Storchaka.

1 files changed, 10 insertions, 0 deletions

diff --git a/Lib/test/test_select.py b/Lib/test/test_select.py
index fe92f45..4ddc217 100644
--- a/Lib/test/test_select.py
+++ b/Lib/test/test_select.py
@@ -49,6 +49,16 @@ class SelectTestCase(unittest.TestCase):
             self.fail('Unexpected return values from select():', rfd, wfd, xfd)
         p.close()
 
+    # Issue 16230: Crash on select resized list
+    def test_select_mutated(self):
+        a = []
+        class F:
+            def fileno(self):
+                del a[-1]
+                return sys.__stdout__.fileno()
+        a[:] = [F()] * 10
+        self.assertEqual(select.select([], a, []), ([], a[:5], []))
+
 def test_main():
     support.run_unittest(SelectTestCase)
     support.reap_children()