title: How to initialize ThreeTen Android backport in a Unit test
body: <p>I use <a href="https://github.com/JakeWharton/ThreeTenABP" rel="noreferrer">this library</a> for storing date &amp; time related data in my app. When the application starts, <code>AndroidThreeTen</code> 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 <code>LocalDate</code>, <code>LocalDateTime</code>, etc.</p>
  
  <p>My current way is like this:</p>
  
  <pre><code>class OverviewViewModelTest {
  
      @Rule
      @JvmField
      val rule = InstantTaskExecutorRule()
  
      @Before
      fun setup() {
          AndroidThreeTen.init(Application())
      }
  
      //...
  }
  </code></pre>
  
  <p>But it throws this error:</p>
  
  <pre><code>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.&lt;clinit&gt;(ZoneRulesProvider.java:82)
      ... 32 more
  </code></pre>
  
  <p>So how can I get this library to work in unit tests?</p>