docstr: StreamQuery - QueryPack - query_execution - start
docstr_tok: ["StreamQuery","-","QueryPack","-","query_execution","-","start"]
code: def test_query_execution_start(self):
      """StreamQuery - QueryPack - query_execution - start"""
  
      self._config.generate_query.return_value = "MOCK QUERY STRING"
      self._execution.athena_client.run_async_query.return_value = (
          "query_id"
      )
  
      assert_equals(self._query_pack.start_query(), "query_id")
  
      self._execution.athena_client.run_async_query.assert_called_with(
          "MOCK QUERY STRING"
      )
  
imports: from datetime import datetime, timezone
  from mock import MagicMock, patch
  from nose.tools import assert_equals, assert_false, assert_true
  from streamalert.scheduled_queries.query_packs.manager import QueryPack, QueryPacksManager, QueryPackExecutionContext, QueryPacksManagerFactory
  from streamalert.scheduled_queries.query_packs.parameters import QueryParameterGenerator
label_desc: Use image node_id 8 for calling the TestQueryPack obj's underlying member method code with example usage: obj.test_query_execution_start() without return types