How mock companion lateinit var?

Question

I try to unit-test my presenter. I have method that update mark and when it failed, app shows toast with translated message.

override fun updateMark(cameraId: Int, markId: Int, createData: MarkCreateData, context: Context) {
        view?.let {
            view?.showOrHideProgressBar(true)
            apiManager.updateMark(cameraId, markId, createData)
                    .subsIoObsMain()
                    .subscribe({
                        view?.showOrHideProgressBar(false)
                        view?.updateMarkSuccess()
                    }) {
                        view?.showOrHideProgressBar(false)
                        view?.showToast(getStringForLayoutByKey("mark_updated_fail"))
                    }.addTo(compositeDisposable)
        }
    }

The method giving the translation is contained in LocalData object that use prefs.

object LocalData {

    private val prefs: SharedPreferences = App.instance.getSharedPreferences(this.javaClass.simpleName, Context.MODE_PRIVATE)

    fun getStringForLayoutByKey(key: String) =
            if (getJsonDataServer().getByKeyOrKeySave(key).isNullOrEmpty()) {
                getJsonDataClient().getByKeyOrKeySave(key) ?: ""
            } else {
                getJsonDataServer().getByKeyOrKeySave(key) ?: ""
            }
}

Prefs init with App.instance that is companion lateinit var.

class App @Inject constructor(): Application(), LifecycleObserver {

    companion object {
        @JvmStatic
        lateinit var instance: App

        @JvmField
        var localData: LocalData? = null
    }

    override fun onCreate() {
        ProcessLifecycleOwner.get().lifecycle.addObserver(this)
        super.onCreate()
        instance = this
        localData = LocalData
        buildDagger()
    }
}

So i try to run my unit test.

@RunWith(MockitoJUnitRunner::class)
class PlayerPresenterTest {
    @Rule
    @JvmField
    val rule = ImmediateSchedulerRule()
    @Mock
    lateinit var apiManager: NetworkManager
    @Mock
    lateinit var playerFragment: PlayerContract.View
    @Mock
    lateinit var context: Context
    @Mock
    lateinit var unknownError: UnknownHostException
    @Mock
    lateinit var localData: LocalData
    @Mock
    lateinit var sharedPreferences: SharedPreferences
    @Mock
    lateinit var app: App.Companion
    @Mock
    lateinit var instance: App

    //variables
    private lateinit var playerPresenter: PlayerPresenter
    private lateinit var markCreateData: MarkCreateData
    private val errorMarkUpdate = "mark updated fail. try later"

    @Before
    fun setup() {
        MockitoAnnotations.initMocks(this)
        MockKAnnotations.init(this, relaxUnitFun = true)

        playerPresenter = PlayerPresenter()
        playerPresenter.attachView(playerFragment)
        playerPresenter.apiManager = apiManager
        markCreateData = MarkCreateData()
    }

    //try update mark and get error
    @Test
    fun test_failed_update_mark() {
        val error = Observable.error<Mark>(unknownError)
        whenever(apiManager.updateMark(cameraId.toInt(), markId.toInt(), markCreateData)).thenReturn(error)

        mockkObject(App)
        every { App } returns app
        every { app.instance } returns instance
        every { instance.getSharedPreferences(this.javaClass.simpleName, Context.MODE_PRIVATE) } returns sharedPreferences
        every { localData.getStringForLayoutByKey("mark_updated_fail") } returns errorMarkUpdate

        playerPresenter.updateMark(cameraId.toInt(), markId.toInt(), markCreateData, context)
        verify(playerFragment, atLeastOnce()).showToast(errorMarkUpdate)
    }
}

and get error "Caused by: kotlin.UninitializedPropertyAccessException: lateinit property instance has not been initialized" that is referenced to LocalData private val prefs initialization. Could smb help me with this? How can i init instance in my unit-test and avoid that error? Or maybe how i have to mock LocalData object without using reference to App.instance?