MainViewModelMockitoUnitTest.kt

class MainViewModel(private val dependency: Any): ViewModel {
  
  fun sampleMethod() {
    viewModelScope.launch {
      val hashCode = dependency.hashCode()
      // TODO: do something with hashCode
  }
}

class MainViewModelUnitTest {

  // Mockito setup goes here
  ...
  
  @get:Rule
  var coroutinesTestRule = CoroutinesTestRule()
  
  @Test
  fun test() = coroutinesTestRule.testDispatcher.runBlockingTest {
    val subject = MainViewModel(mockObject)
    subject.sampleMethod()
    // Checks mockObject called the hashCode method that is expected from the coroutine created in sampleMethod
    verify(mockObject).hashCode()
  }
}