Add a test on error followed by success

Author: rschlaikjer

tests/test_connection.py

@@ -5,6 +5,7 @@
 import selectors
 import socket
 import ssl
+import sys
 import threading
 import time
 import types
@@ -603,6 +604,40 @@ def test_connect_breaks_exception_reference_cycle(self):
         assert connect_frame is not None
         assert connect_frame.f_locals.get("err") is None
 
+    def test_connect_breaks_reference_cycle_when_a_later_address_succeeds(self):
+        """
+        When an address fails but a later one connects, _connect must not
+        return while still holding the caught exception.
+        The exception's traceback references the frame, so a retained local
+        would form a cycle only reclaimable by the GC.
+        """
+        conn = Connection(host="localhost", port=6379)
+        addr_infos = [
+            (socket.AF_INET, socket.SOCK_STREAM, 0, "", ("127.0.0.1", 6379)),
+            (socket.AF_INET, socket.SOCK_STREAM, 0, "", ("127.0.0.2", 6379)),
+        ]
+
+        # _connect calls getaddrinfo, so hook that as a way to peek the caller
+        connect_frames = []
+
+        def capturing_getaddrinfo(*args, **kwargs):
+            connect_frames.append(sys._getframe(1))
+            return addr_infos
+
+        failing_sock, working_sock = MagicMock(), MagicMock()
+        failing_sock.connect.side_effect = OSError("refused")
+
+        with (
+            patch.object(socket, "getaddrinfo", capturing_getaddrinfo),
+            patch.object(socket, "socket", side_effect=[failing_sock, working_sock]),
+        ):
+            assert conn._connect() is working_sock
+
+        # Error should be cleared in the connect frame
+        assert len(connect_frames) == 1
+        (connect_frame,) = connect_frames
+        assert connect_frame.f_locals.get("err") is None
+
     @pytest.mark.parametrize(
         "connection_kwargs",
         [