Contacts.kt

data class Contact(val name:String, val phoneNum:String)

interface ContactsListsApi{
  fetchContacts(): Single<List<Contact>>
}
interface ContactsListsContract{
  interface View{
    fun showProgress()
    fun hideProgress()
    fun setData(contacts: List<Contact>)
    fun showError(errorMessage:String)
  }
  interface Presenter{
    fun fetchContacts()
  }
}

class ContactsListPresenter(val view: ContactsListsContract.View, val api:ContactsListsApi): ContactsListsContract.Presenter {
  override fun fetchContacts(){
  }
}

ContactsTests.kt

@Mock lateinit var view: ContactsListsContract.View
@Mock lateinit var api: ContactsListsApi
lateinit var presenter: ContactsListPresenter

@Before
fun setUp(){
  MockitoAnnotations.init(this)
  presenter = ContactsListPresenter(view, api)
}

@Test
fun `fetch contacts, success`(){
  //given
  whenver(api.fetchContacts()).thenReturn{Single.just(emptyList())}
  //when
  presenter.fetchContacts()
  //then
  val inOrder = inOrder(view, api)
  inOrder.verify(view).showProgress()
  inOrder.verify(api).fetchContacts()
  inOrder.verify(view).hideProgress()
  inOrder.verify(view).setData(anyList)
  inOrder.verifyNoMoreInteractions()
}