test: test for on_connect to handle AUTH failure

Author: zeze1004

tests/test_connection.py

@@ -210,6 +210,60 @@ def test_on_connect_fail_hello(self, mock_read_response, mock_send_command):
         mock_send_command.assert_called()
         mock_read_response.assert_called()
 
+    @patch.object(Connection, 'send_command')
+    @patch.object(Connection, 'read_response')
+    def test_on_connect_fail_auth(self, mock_read_response, mock_send_command):
+        """Test that on_connect handles connection failure AUTH command"""
+        conn = Connection()
+
+        conn._parser = MagicMock()
+        conn._parser.on_connect.return_value = None
+        conn.credential_provider = None
+        conn.username = "myuser"
+        conn.password = "wrong-password"
+        conn.protocol = 3
+        conn.client_name = "test-client"
+        conn.lib_name = "test"
+        conn.lib_version = "1234"
+        conn.db = 1
+        conn.client_cache = True
+
+        # simulate a failure in the HELLO command response
+        mock_read_response.side_effect = itertools.cycle([
+            {"proto": 3, "version": "6"},   # HELLO
+            b'QUEUED',  # MULTI
+            b'QUEUED',  # AUTH
+            b'QUEUED',  # CLIENT SETNAME
+            b'QUEUED',  # CLIENT SETINFO LIB-NAME
+            b'QUEUED',  # CLIENT SETINFO LIB-VER
+            b'QUEUED',  # SELECT
+            b'QUEUED',  # CLIENT TRACKING ON
+            [
+                {"proto": 3, "version": "6"},  # HELLO response
+                b'ERR invalid password',  # AUTH response
+                b'OK',  # CLIENT SETNAME response
+                b'OK',  # CLIENT SETINFO LIB-NAME response
+                b'OK',  # CLIENT SETINFO LIB-VER response
+                b'OK',  # SELECT response
+                b'OK'   # CLIENT TRACKING ON response
+            ]
+        ])
+
+        with self.assertRaises(AuthenticationError):
+            conn.on_connect()
+
+        mock_send_command.assert_any_call(
+            'HELLO', 3, 'AUTH', 'myuser', 'wrong-password'),
+        mock_send_command.assert_any_call('CLIENT', 'SETNAME', 'test-client'),
+        mock_send_command.assert_any_call('CLIENT', 'SETINFO', 'LIB-NAME', 'test'),
+        mock_send_command.assert_any_call('CLIENT', 'SETINFO', 'LIB-VER', '1234'),
+        mock_send_command.assert_any_call('SELECT', 1),
+        mock_send_command.assert_any_call('CLIENT', 'TRACKING', 'ON'),
+        mock_send_command.assert_any_call('EXEC')
+
+        mock_send_command.assert_called()
+        mock_read_response.assert_called()
+
 
 
 @pytest.mark.onlynoncluster