docstr: updating records updates tracked buffer size
docstr_tok: ["updating","records","updates","tracked","buffer","size"]
code: def test_cull_size_update(self):
      """updating records updates tracked buffer size"""
      self.db = (
          self.create_db()
      )  # skip the load-records init from setUp
      self.db.size_limit = 1000
      self.db.cull_fraction = 0.2
      self.load_records(100, buffer_size=10)
      assert len(self.db.get_history()) == 100
      msg_id = self.db.get_history()[-1]
      self.db.update_record(
          msg_id, dict(result_buffers=[os.urandom(10)], buffers=[])
      )
      assert len(self.db.get_history()) == 100
      self.db.update_record(
          msg_id, dict(result_buffers=[os.urandom(11)], buffers=[])
      )
      assert len(self.db.get_history()) == 79
  
imports: import logging
  import os
  import tempfile
  import time
  from datetime import datetime, timedelta
  from unittest import TestCase
  import pytest
  from jupyter_client.session import Session
  from ipyparallel import util
  from ipyparallel.controller.dictdb import DictDB
  from ipyparallel.controller.hub import init_record
  from ipyparallel.controller.sqlitedb import SQLiteDB
  from ipyparallel.util import utc
label_desc: Use image node_id 5 for calling the TestDictBackend obj's underlying member method code with example usage: obj.test_cull_size_update() without return types