code: public function persist($testSessionId)
      {
          $extendedState = $this->getExtendedState($testSessionId);
          $extendedState->save();
          $this->getStorageService()->persist($extendedState->getUserId(), $extendedState->getStorageKey());
      }
docs: Persists the extended state
  @param string $testSessionId
  @throws \common_exception_Error