Solution: All users flow
class AllUsers(private val repository: UserRepository) {
fun getAllUsers(): Flow<User> = flow {
var pageNumber = 0
do {
val users = repository.fetchUsers(pageNumber)
users.forEach { emit(it) }
pageNumber++
} while (users.isNotEmpty())
}
}
Example solution in playground
import kotlinx.coroutines.flow.Flow
import kotlinx.coroutines.flow.count
import kotlinx.coroutines.flow.flow
import kotlinx.coroutines.test.runTest
import org.junit.Test
import kotlin.test.assertEquals
class AllUsers(private val repository: UserRepository) {
fun getAllUsers(): Flow<User> = flow {
var pageNumber = 0
do {
val users = repository.fetchUsers(pageNumber)
users.forEach { emit(it) }
pageNumber++
} while (users.isNotEmpty())
}
}
interface UserRepository {
fun fetchUsers(pageNumber: Int): List<User>
}
data class User(val name: String)
internal class AllUsersTests {
@Test
fun test() = runTest {
val size = 10_000
val pageSize = 10
val repo = object : UserRepository {
val users = List(size) { User("User$it") }
var timesUsed = 0
override fun fetchUsers(pageNumber: Int): List<User> =
users.drop(pageSize * pageNumber)
.take(pageSize)
.also { timesUsed++ }
}
val service = AllUsers(repo)
val s = service.getAllUsers()
assertEquals(size, s.count())
assertEquals(size / pageSize + 1, repo.timesUsed)
}
}
