Using components private functions using Enzyme in Jest

Question

I'm looking at the answers here: How to unit test a method of react component?

I'm trying to use a components private function in one of my jest tests but when I do the following:

const nPanel = shallow(<NotificationsPanel />);
nPanel.dive().instance().openPanel(true);

But I get an error in my IDE (and when i run the test):

 Property 'openPanel' does not exist on type 'Component<{}, {}, any>'

Which it definitely doesn't. I'm using Typescript so do I need to type the instance or something? NotificationsPanel isn't a type so I cant do as NotificationsPanel.

I'm not sure where to go from here with it.

Here is the openPanel code:

const openPanel = useCallback((openState: boolean) =>
    {
        setOpen((previousValue) =>
        {
            if (openState != null)
            {
                return openState;
            }
            else
            {
                return !previousValue;
            }
        });

        setOpenedDateTime(Date.now());
    }, []);