code: def test_column_hash_property(self):
      # Test column_hash property
      mock_df = Mock()
      mock_df.columns = ["Column1", "Column2"]
      self.connector.head = Mock(return_value=mock_df)
      column_hash = self.connector.column_hash
      self.assertIsNotNone(column_hash)
      self.assertEqual(
          column_hash,
          "ea6a80582b83e1511f8be83412b13e7b86d20c45b96fcf9731f3b99dc3b568aa",
      )
  
imports: import unittest
  import pandas
  from unittest.mock import Mock, patch
  from pandasai.connectors.base import SQLConnectorConfig
  from pandasai.connectors.sql import PostgreSQLConnector, SQLConnector
  from pandasai.exceptions import MaliciousQueryError
label_desc: Use image node_id 8 for calling the TestSQLConnector obj's underlying member method code with example usage: obj.test_column_hash_property() without return types