如何使用Powermock模拟具有RxJava的私有方法？

Question

TrendingViewModel

class TrendingViewModel(
val trendingRepository: TrendingRepository
) : ViewModel() {

fun fetchTrendingRepos() {
    if (isConnected) {
        compositeDisposable.add(
            trendingRepository.getTrendingRepos().subscribeOn(Schedulers.io())
                .observeOn(AndroidSchedulers.mainThread())
                .subscribe({ response ->
                    run {
                        saveDataToDb(response)

                    }
                },
                    { error ->

                    }
                )
        )
    }


private fun saveDataToDb(response: List<TrendingRepo>) {
    trendingRepository.insertTrendingUsers(response)
        .subscribeOn(Schedulers.io())
        .observeOn(Schedulers.io())
        .subscribe(object : DisposableCompletableObserver() {
            override fun onComplete() {
                Log.d("Status", "Save Success")
            }

            override fun onError(e: Throwable) {
                Log.d("Status", "error ${e.localizedMessage}")
            }
        })
}

TrendingViewModelTest

@RunWith(JUnit4::class)
class TrendingViewModelTest {
@Test
fun testWithNetwork() {
    trendingViewModel.isConnected = true
    Mockito.`when`(trendingRepository.getTrendingRepos()).thenReturn(
        Single.just(list) )
    trendingViewModel.fetchTrendingRepos()
  //  trendingRepository.insertTrendingUsers(list).blockingAwait()
    verify(trendingRepository, times(1)).getTrendingRepos()
}