The esample with RX

MainPresenterRX.kt

package com.mcatta.mockksample.ui

import com.mcatta.mockksample.data.DataRepository
import com.mcatta.mockksample.domain.DataModel
import io.reactivex.Single
import io.reactivex.SingleObserver
import io.reactivex.disposables.Disposable
import io.reactivex.schedulers.Schedulers
import java.util.*

class MainPresenter(
    private val view: MainContract.View,
    private val dataRepository: DataRepository
) : MainContract.Presenter {

    override fun fetchDataViaRX() {
        dataRepository.fetchDataWithRX()
            .flatMap { result ->
                val output =
                    result.map { UiDataModel(UUID.randomUUID().toString(), it.id, it.value) }
                Single.just(output)
            }
            .subscribe(object : SingleObserver<List<UiDataModel>> {
                override fun onSuccess(t: List<UiDataModel>) {
                    view.onResult(t)
                }

                override fun onSubscribe(d: Disposable) {}

                override fun onError(e: Throwable) {
                    view.onError(e)
                }

            })
    }

}