MainDispatcherRule.kt

class MainDispatcherRule(
  val dispatcher = TestCoroutineDispatcher()
) : TestWatcher() {

  override fun starting(description: Description?) {
    super.starting(description)
    Dispatchers.setMain(dispatcher)
  }

  override fun finished(description: Description?) {
    super.finished(description)
    Dispatchers.resetMain()
    dispatcher.cleanupTestCoroutines()
  }
}