@spy Mockito for map or switchMap livedata

I have a map liveData in view model.

val isOpen: LiveData<Boolean> = Transformations.map(shouldTry) {
        println("in map")
        close()
        false
}
    
fun open() {
        println("open called")
}

how can use @spy for open called or not?

@Test
fun test() :runBlockingTest{
    
        viewModel = spy(ViewModel())
        
        // Action
        viewModel.shouldTry.value = true

        // Expected
        verify(viewModel).open()
}