RxJavaErrorHandling2.kt

class RxJavaUnitTest {

  companion object {
    private const val NAME = "John Doe"
    private const val AGE = 20
    private const val EMPTY = ""
  }

  @Test
  fun getUserWithError() {
    getUserId()
      .flatMap(this::getUser)
      .flatMap(this::saveUser)
      .subscribe { user ->
        if (user.hasError) {
          println("user ID is invalid")
        } else {
          println(user)
        }
      }
  }

  private fun getUserId(): Observable<String> {
    return Observable.fromCallable {
      EMPTY
    }
  }

  private fun getUser(id: String): Observable<User> {
    if (id == EMPTY) {
      val defaultUser = User(
        id = EMPTY,
        name = EMPTY,
        age = -1,
        hasError = true
      )
      return Observable.just(defaultUser)
    }
    val user = User(
        id = id,
        name = NAME,
        age =  AGE
    )
    return Observable.fromCallable { user }
  }

  private fun saveUser(user: User): Observable<User> {
    if (user.hasError) {
      return Observable.just(user)
    }
    // Perform save to user
    return Observable.fromCallable { user }
  }
}

data class User(
  val id: String,
  val name: String,
  val age: Int,
  var hasError: Boolean = false
)