code: def test_serialize_cell(self):
      assert "foo" == self.db_hook._serialize_cell("foo", None)
  
imports: from __future__ import annotations
  import json
  import os
  import uuid
  from contextlib import closing
  from unittest import mock
  import pytest
  from airflow.models import Connection
  from airflow.models.dag import DAG
  from airflow.utils import timezone
  from tests.test_utils.asserts import assert_equal_ignore_multiple_spaces
label_desc: Use image node_id 12 for calling the TestMySqlHook obj's underlying member method code with example usage: obj.test_serialize_cell() without return types