docstr: StreamQuery - QueryPack - query_execution - before start
docstr_tok: ["StreamQuery","-","QueryPack","-","query_execution","-","before","start"]
code: def test_query_execution_before_start(self):
      """StreamQuery - QueryPack - query_execution - before start"""
      assert_equals(self._query_pack.query_execution, None)
  
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 7 for calling the TestQueryPack obj's underlying member method code with example usage: obj.test_query_execution_before_start() without return types