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/*
* Copyright 2017-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
*/
package kotlinx.serialization
import kotlinx.serialization.descriptors.*
import kotlinx.serialization.encoding.*
import kotlinx.serialization.json.*
import kotlinx.serialization.test.*
import kotlin.test.*
public class SerializerForNullableTypeTest : JsonTestBase() {
// Nullable boxes
@Serializable(with = StringHolderSerializer::class)
data class StringHolder(val s: String)
object StringHolderSerializer : KSerializer<StringHolder?> {
override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("SHS", PrimitiveKind.STRING).nullable
override fun serialize(encoder: Encoder, value: StringHolder?) {
if (value == null) encoder.encodeString("nullable")
else encoder.encodeString("non-nullable")
}
override fun deserialize(decoder: Decoder): StringHolder? {
if (decoder.decodeNotNullMark()) {
return StringHolder("non-null: " + decoder.decodeString())
}
decoder.decodeNull()
return StringHolder("nullable")
}
}
@Serializable
data class Box(val s: StringHolder?)
@Test
fun testNullableBoxWithNotNull() {
val b = Box(StringHolder("box"))
val string = Json.encodeToString(b)
assertEquals("""{"s":"non-nullable"}""", string)
val deserialized = Json.decodeFromString<Box>(string)
assertEquals(Box(StringHolder("non-null: non-nullable")), deserialized)
}
@Test
fun testNullableBoxWithNull() {
val b = Box(null)
val string = Json.encodeToString(b)
assertEquals("""{"s":"nullable"}""", string)
val deserialized = Json.decodeFromString<Box>(string)
assertEquals(Box(StringHolder("non-null: nullable")), deserialized)
}
@Test
fun testNullableBoxDeserializeNull() {
val deserialized = Json.decodeFromString<Box>("""{"s":null}""")
assertEquals(Box(StringHolder("nullable")), deserialized)
}
// Nullable primitives
object NullableLongSerializer : KSerializer<Long?> {
@Serializable
data class OptionalLong(val initialized: Boolean, val value: Long? = 0)
override val descriptor: SerialDescriptor = buildClassSerialDescriptor("NLS") {
element<Boolean>("initialized")
element<Long?>("value")
}.nullable
override fun serialize(encoder: Encoder, value: Long?) {
val opt = OptionalLong(value != null, value)
encoder.encodeSerializableValue(OptionalLong.serializer(), opt)
}
override fun deserialize(decoder: Decoder): Long? {
val value = decoder.decodeSerializableValue(OptionalLong.serializer())
return if (value.initialized) value.value else null
}
}
@Serializable
data class NullablePrimitive(
@Serializable(with = NullableLongSerializer::class) val value: Long?
)
@Test
fun testNullableLongWithNotNull() {
val data = NullablePrimitive(42)
val json = Json.encodeToString(data)
assertEquals("""{"value":{"initialized":true,"value":42}}""", Json.encodeToString(data))
assertEquals(data, Json.decodeFromString(json))
}
@Test
fun testNullableLongWithNull() {
val data = NullablePrimitive(null)
val json = Json.encodeToString(data)
assertEquals("""{"value":{"initialized":false,"value":null}}""", Json.encodeToString(data))
assertEquals(data, Json.decodeFromString(json))
}
// Now generics
@Serializable
data class GenericNullableBox<T: Any>(val value: T?)
@Serializable
data class GenericBox<T>(val value: T?)
@Test
fun testGenericBoxNullable() {
val data = GenericBox<StringHolder?>(null)
val json = Json.encodeToString(data)
assertEquals("""{"value":"nullable"}""", Json.encodeToString(data))
assertEquals(GenericBox(StringHolder("non-null: nullable")), Json.decodeFromString(json))
}
@Test
fun testGenericNullableBoxFromNull() {
assertEquals(GenericBox(StringHolder("nullable")), Json.decodeFromString("""{"value":null}"""))
}
@Test
fun testGenericNullableBoxNullable() {
val data = GenericNullableBox<StringHolder>(null)
val json = Json.encodeToString(data)
assertEquals("""{"value":"nullable"}""", Json.encodeToString(data))
assertEquals(GenericNullableBox(StringHolder("non-null: nullable")), Json.decodeFromString(json))
}
@Test
fun testGenericBoxNullableFromNull() {
assertEquals(GenericNullableBox(StringHolder("nullable")), Json.decodeFromString("""{"value":null}"""))
}
}
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