jraska

fun <K, V> lazyMap(initializer: (K) -> V): Map<K, V> {
  val map = mutableMapOf<K, V>()
  return map.withDefault { key ->
    val newValue = initializer(key)
    map[key] = newValue
    return@withDefault newValue
  }
}

jraska

class ContactsViewModel(val getContactsUseCase: GetContactsUseCase) : ViewModel() {
  private val contactsLiveData: Map<Parameters, LiveData<Contacts>> = lazyMap { parameters ->
    val liveData = MutableLiveData<Contacts>()
    getContactsUseCase.loadContacts(parameters) { liveData.value = it }
    return@lazyMap liveData
  }

  fun contacts(parameters: Parameters): LiveData<Contacts> = contactsLiveData.getValue(parameters)
}

jraska

class ContactsViewModel(val getContactsUseCase: GetContactsUseCase) : ViewModel() {
  private val contactsLiveData = MutableLiveData<Contacts>()

  fun loadContacts(parameters: Parameters) {
    getContactsUseCase.loadContacts(parameters) { contactsLiveData.value = it }
  }

  fun contacts(): LiveData<Contacts> = contactsLiveData
}

jraska

class GetContactsUseCase {
  fun loadContacts(parameters: Parameters): Flowable<Contacts> { /* Implementation detail */ }
}

class ContactsViewModel(val getContactsUseCase: GetContactsUseCase) : ViewModel() {
  fun contacts(parameters: Parameters): LiveData<Contacts> {
    return getContactsUseCase.loadContacts(parameters).toLiveData()
  }
}

jraska

class ContactsViewModel(val getContactsUseCase: GetContactsUseCase) : ViewModel() {
  private val contactsLiveData by lazy {
    val liveData = MutableLiveData<Contacts>()
    getContactsUseCase.loadContacts(Parameters()) { liveData.value = it }
    return@lazy liveData
  }

  fun contacts(): LiveData<Contacts> = contactsLiveData
}

jraska

class ContactsViewModel(val getContactsUseCase: GetContactsUseCase) : ViewModel() {
  private val contactsLiveData = MutableLiveData<Contacts>()

  init {
    getContactsUseCase.loadContacts(Parameters()) { contactsLiveData.value = it }
  }

  fun contacts(): LiveData<Contacts> = contactsLiveData
}

jraska

class Contacts(val names: List<String>)

data class Parameters(val namePrefix: String = "")

class GetContactsUseCase {
  fun loadContacts(parameters: Parameters, onLoad: (Contacts) -> Unit) { /* Implementation detail */ }
}

class ContactsViewModel(val getContactsUseCase: GetContactsUseCase) : ViewModel() {
  // TODO When to call getContactsUseCase.loadContacts?

jraska

  @Test
  fun writePostAndReadInList() {
    val testObserver = postDao.getAll().test()
    testObserver.assertValue { it.isEmpty() }

    val post = TestUtil.createPost(id = 42)
    postDao.insert(post)

    testObserver.assertValue { it.size == 1 }
  }

jraska

class ViewModelFactory @Inject constructor(val providersMap: Map<Class<*>, Provider<ViewModel>>) 
  : ViewModelProvider.Factory {
  
  override fun <T : ViewModel> create(aClass: Class<T>): T {
    val provider = providersMap[aClass] ?: throw IllegalArgumentException("No $aClass provider")
    return provider.get() as T
  }
}

jraska

interface Navigator {
  fun startUserDetail(login: String)

  fun startRepoDetail(fullPath: String)
}