docstr: DB Eng Specs (postgres): Test test_query_cost_formatter example costs
docstr_tok: ["DB","Eng","Specs","(","postgres",")",":","Test","test_query_cost_formatter","example","costs"]
code: def test_query_cost_formatter_example_costs(self):
      """
      DB Eng Specs (postgres): Test test_query_cost_formatter example costs
      """
      raw_cost = [
          {
              "Start-up cost": 0.00,
              "Total cost": 1537.91,
          },
          {
              "Start-up cost": 10.00,
              "Total cost": 1537.00,
          },
      ]
      result = PostgresEngineSpec.query_cost_formatter(raw_cost)
      self.assertEqual(
          result,
          [
              {
                  "Start-up cost": "0.0",
                  "Total cost": "1537.91",
              },
              {
                  "Start-up cost": "10.0",
                  "Total cost": "1537.0",
              },
          ],
      )
  
imports: from textwrap import dedent
  from unittest import mock
  from flask.ctx import AppContext
  from sqlalchemy import column, literal_column
  from sqlalchemy.dialects import postgresql
  from superset.db_engine_specs import load_engine_specs
  from superset.db_engine_specs.postgres import PostgresEngineSpec
  from superset.errors import ErrorLevel, SupersetError, SupersetErrorType
  from superset.models.sql_lab import Query
  from superset.utils.database import get_example_database
  from tests.integration_tests.db_engine_specs.base_tests import TestDbEngineSpec
  from tests.integration_tests.fixtures.certificates import ssl_certificate
  from tests.integration_tests.fixtures.database import default_db_extra
label_desc: Use image node_id 14 for calling the TestPostgresDbEngineSpec obj's underlying member method code with example usage: obj.test_query_cost_formatter_example_costs() without return types