How to initialize ThreeTen Android backport in a Unit test

I use this library for storing date & time related data in my app. When the application starts, AndroidThreeTen is initialized first to function properly. So I want to ask how to initialize it when unit testing? E.g. I want to test using LocalDate, LocalDateTime, etc.

My current way is like this:

class OverviewViewModelTest {


    @Rule
    @JvmField
    val rule = InstantTaskExecutorRule()

    @Before
    fun setup() {
        AndroidThreeTen.init(Application())
    }

    //...

}

But it throws this error:

java.lang.ExceptionInInitializerError
    at org.threeten.bp.ZoneRegion.ofId(ZoneRegion.java:143)
    at org.threeten.bp.ZoneId.of(ZoneId.java:358)
    at org.threeten.bp.ZoneId.of(ZoneId.java:286)
    at org.threeten.bp.ZoneId.systemDefault(ZoneId.java:245)

    at org.threeten.bp.Clock.systemDefaultZone(Clock.java:137)
    at org.threeten.bp.LocalDate.now(LocalDate.java:165)
Caused by: java.lang.RuntimeException: Method getAssets in android.content.ContextWrapper not mocked. See http://g.co/androidstudio/not-mocked for details.
    at android.content.ContextWrapper.getAssets(ContextWrapper.java)
    at com.jakewharton.threetenabp.AssetsZoneRulesInitializer.initializeProviders(AssetsZoneRulesInitializer.java:22)
    at org.threeten.bp.zone.ZoneRulesInitializer.initialize(ZoneRulesInitializer.java:89)
    at org.threeten.bp.zone.ZoneRulesProvider.(ZoneRulesProvider.java:82)
    ... 32 more

So how can I get this library to work in unit tests?