Solution: Conversion and measurement unit creation
fun User.toUserJson(): UserJson = UserJson(
username = username,
email = email.value,
registrationDate = registrationDate.toString(),
heightCm = height.value,
)
fun UserJson.toUser(): User = User(
username = username,
email = Email(email),
registrationDate = LocalDateTime.parse(registrationDate),
height = heightCm.cm,
)
val Int.cm: Centimeters get() = Centimeters(this)
Example solution in playground
import org.junit.Test
import java.time.LocalDateTime
import kotlin.test.assertEquals
fun User.toUserJson(): UserJson = UserJson(
username = username,
email = email.value,
registrationDate = registrationDate.toString(),
heightCm = height.value,
)
fun UserJson.toUser(): User = User(
username = username,
email = Email(email),
registrationDate = LocalDateTime.parse(registrationDate),
height = heightCm.cm,
)
val Int.cm: Centimeters get() = Centimeters(this)
data class User(
val username: String,
val email: Email,
val registrationDate: LocalDateTime,
val height: Centimeters,
)
data class Email(val value: String)
data class Centimeters(val value: Int)
data class UserJson(
val username: String,
val email: String,
val registrationDate: String,
val heightCm: Int,
)
// TODO: Implement extensions to convert User to UserJson and vice versa,
// and to create Centimeters from Int
fun main() {
val user = User(
username = "alex",
email = Email("alex@example.com"),
registrationDate = LocalDateTime
.of(1410, 7, 15, 10, 13),
height = 170.cm,
)
val userJson = user.toUserJson()
println(userJson)
// UserJson(username=alex, email=alex@example.com,
// registrationDate=1410-07-15T10:13, heightCm=170)
val user2 = userJson.toUser()
println(user2) // User(username=alex,
// email=Email(value=alex@example.com),
// registrationDate=1410-07-15T10:13,
// height=Centimeters(value=170))
}
class DataConversionTest {
@Test
fun `test User to UserJson conversion`() {
val user = User(
username = "alex",
email = Email("alex@example.com"),
registrationDate = LocalDateTime.now(),
height = 170.cm
)
val userJson = user.toUserJson()
assertEquals("alex", userJson.username)
assertEquals("alex@example.com", userJson.email)
assertEquals(user.registrationDate.toString(), userJson.registrationDate)
assertEquals(user.height.value, userJson.heightCm)
}
@Test
fun `test UserJson to User conversion`() {
val userJson = UserJson(
username = "alex",
email = "alex@example.com",
registrationDate = LocalDateTime.now().toString(),
heightCm = 170
)
val user = userJson.toUser()
assertEquals("alex", user.username)
assertEquals("alex@example.com", user.email.value)
assertEquals(userJson.registrationDate, user.registrationDate.toString())
assertEquals(userJson.heightCm.cm, user.height)
}
@Test
fun `test cm extension property`() {
val value = 150
val cm = value.cm
assertEquals(value, cm.value)
}
}
