def METHOD_NAME(self):
    with patch("src.chain.web3.get_web3") as mock_function:
        with patch(
            "src.chain.web3.Config.polygon_mumbai.private_key",
            DEFAULT_GAS_PAYER_PRIV,
        ):
            mock_function.return_value = self.w3
            signed_message = sign_message(ChainId.POLYGON_MUMBAI.value, "message")
        self.assertEqual(signed_message, SIGNATURE)