// verifyNoEvents verifies there is no event generated
func verifyNoEvents(e coreclientset.EventInterface, options api.ListOptions) error {
	events, err := e.List(options)
	if err != nil {
		return err
	}
	if len(events.Items) != 0 {
		return fmt.Errorf("unexpected events: %v", events.Items)
	}
	return nil
}
// verifyEvents verifies there are num specific events generated
func verifyEvents(e coreclientset.EventInterface, options api.ListOptions, num int, reason, message string) error {
	events, err := e.List(options)
	if err != nil {
		return err
	}
	count := 0
	for _, event := range events.Items {
		if event.Reason != reason || event.Message != message {
			return fmt.Errorf("unexpected event: %v", event)
		}
		count += int(event.Count)
	}
	if count != num {
		return fmt.Errorf("expect event number %d, got %d: %v", num, count, events.Items)
	}
	return nil
}