PromotionRepositoryTest.kt

import io.reactivex.android.plugins.RxAndroidPlugins
import io.reactivex.plugins.RxJavaPlugins
import io.reactivex.schedulers.Schedulers
import okhttp3.MediaType
import okhttp3.ResponseBody
import org.junit.Before
import org.junit.Test
import org.mockito.ArgumentMatchers.any
import org.mockito.Mock
import org.mockito.Mockito
import org.mockito.MockitoAnnotations
import retrofit2.HttpException
import retrofit2.Response


class PromotionRepositoryTest {

    @Mock
    private lateinit var promotionService: PromotionService

    private lateinit var promotionRepository: PromotionRepository

    @Before
    fun setUp() {

        RxJavaPlugins.setIoSchedulerHandler { Schedulers.trampoline() }
        RxJavaPlugins.setNewThreadSchedulerHandler { Schedulers.trampoline() }
        RxJavaPlugins.setComputationSchedulerHandler { Schedulers.trampoline() }
        RxJavaPlugins.setSingleSchedulerHandler { Schedulers.trampoline() }
        RxAndroidPlugins.setMainThreadSchedulerHandler { Schedulers.trampoline() }

        MockitoAnnotations.initMocks(this)

        promotionRepository = PromotionRepository(
            promotionService
        )

    }

    private fun <T> serverError500(): Response<T> {
        return Response.error<T>(
            500,
            ResponseBody.create(
                MediaType.parse("application/json"),
                "{\"code\":500,\"message\":\"Internal Server Error\"}"
            )
        )
    }


    @Test
    fun testFetchAdsFail(){
        Mockito.`when`(promotionService.fetchAds(any()))
            .thenReturn(Single.just(serverError500()))
        val receivedAds = promotionRepository.fetchAds(1)
        // it's important to note the response is already consumed by the repository class
        // so when we want to crosscheck the error, we need to build that again
        // that's why we call serverError500<List<Ad>>() again
        receivedAds.test()
            .assertError(HttpException(serverError500<List<Ad>>()))
    }

    @Test
    fun testFetchAdsSuccess(){
        val ads = listOf(
            Ad(),
            Ad()
        )
        Mockito.`when`(promotionService.fetchAds(any()))
            .thenReturn(Single.just(Response.success(ads)))
        val receivedAds = promotionRepository.fetchAds(1)
        receivedAds.test()
            .assertValue { it.get() == ads }
    }

    @Test
    fun testFetchAdsSuccessNull(){
        Mockito.`when`(promotionService.fetchAds(any()))
            .thenReturn(Single.just(Response.success(null)))
        val receivedAds = promotionRepository.fetchAds(1)
        receivedAds.test()
            .assertValue { it.isEmpty }
    }


}