docstr: Apply default values to the given test event
docstr_tok: ["Apply","default","values","to","the","given","test","event"]
code: def _apply_defaults(self, config):
      """Apply default values to the given test event"""
      if not self.override_record:
          return
  
      # The existence of this is checked in the is_valid function
      event_log = config["logs"].get(self.log)
  
      configuration = event_log.get("configuration", {})
      schema = configuration.get("envelope_keys", event_log["schema"])
  
      # Add apply default values based on the declared schema
      default_test_event = {
          key: ParserBase.default_optional_values(value)
          for key, value in schema.items()
      }
  
      # Overwrite the fields included in the 'override_record' field,
      # and update the test event with a full 'data' key
      default_test_event.update(self.override_record)
      self._event["data"] = default_test_event
  
imports: import base64
  import json
  import re
  import time
  import zlib
  from mock import patch
  from streamalert.classifier.parsers import ParserBase
  from streamalert.shared import rule
  from streamalert.shared.logger import get_logger
  from streamalert_cli.test.mocks import LookupTableMocks, ThreatIntelMocks
label_desc: Use image node_id 26 for calling the TestEvent obj's underlying member method code with example usage: obj._apply_defaults(config) without return types