UseCaseWithErrorsExample.kt

class GetMagicCardUseCase(
    private val mtgApi : MagicTheGatheringApi
) {

    suspend operator fun invoke(cardName: String) : Result<MagicCard, GetMagicCardUseCaseError> {
        if (!isCardNameValid(cardName)) {
            return Error(InvalidCardNameFormat)
        }

        return try {
            Success(mtgApi.getCard(cardName))
        } catch (t: Throwable) {
            val error = when (t) {
                is IOException -> RemoteServerNotReachedError
                is HttpException -> HttpUnsuccessfulCodeError(t.code())
                else -> UnexpectedApiCommunicationError
            }

            return Error(error)
        }
    }
}

sealed class GetMagicCardUseCaseError

object InvalidCardNameFormat : GetMagicCardUseCaseError()
class HttpUnsuccessfulCodeError(val httpCode: Int) : GetMagicCardUseCaseError()
object RemoteServerNotReachedError : GetMagicCardUseCaseError()
object UnexpectedApiCommunicationError : GetMagicCardUseCaseError()