Vue: How to test function within another function with Vitest

Question

So I have this function inside my Vue Component:

function openLink(event: Event, url: string, type: string) {
  switch (type) {
    case 'onetype':
    case 'twotype':
      event.preventDefault()
      openURLInBrowser(url, '_blank');
      break
  }
}

I am writing my unit test with Vitest. I can easily test, if openLink have been called:

const wrapper = shallowMount(MyLinks, {
    propsData: {
       myLinks: linkDataStructure
    }
})

const a = wrapper.find('a');
const openLink= vi.spyOn(wrapper.vm, 'openLink')

await a.trigger('click');
expect(openLink).toHaveBeenCalled()

This works great. Now I need to test the case, if type is onetype, the method openURLInBrowser is called. So basically the switchcase inside the openLink function.

If I use following, I get: openURLInBrowser does not exist.

const openLink= vi.spyOn(wrapper.vm, 'openURLInBrowser')

How can I access this method inside the function to test it?

Note: The function openURLInBrowser is imported from a openURLInBrowser.ts-File.