1 files changed, 137 insertions, 0 deletions
diff --git a/formats/json-tests/commonTest/src/kotlinx/serialization/features/ContextAndPolymorphicTest.kt b/formats/json-tests/commonTest/src/kotlinx/serialization/features/ContextAndPolymorphicTest.kt
new file mode 100644
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--- /dev/null
+++ b/formats/json-tests/commonTest/src/kotlinx/serialization/features/ContextAndPolymorphicTest.kt
@@ -0,0 +1,137 @@
+/*
+ * Copyright 2017-2020 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+package kotlinx.serialization.features
+
+import kotlinx.serialization.*
+import kotlinx.serialization.builtins.*
+import kotlinx.serialization.descriptors.*
+import kotlinx.serialization.encoding.*
+import kotlinx.serialization.json.*
+import kotlinx.serialization.modules.*
+import kotlinx.serialization.test.*
+import kotlin.test.*
+
+class ContextAndPolymorphicTest {
+
+    @Serializable
+    data class Data(val a: Int, val b: Int = 42)
+
+    @Serializable
+    data class EnhancedData(
+        val data: Data,
+        @Contextual val stringPayload: Payload,
+        @Serializable(with = BinaryPayloadSerializer::class) val binaryPayload: Payload
+    )
+
+    @Serializable
+    @SerialName("Payload")
+    data class Payload(val s: String)
+
+    @Serializable
+    data class PayloadList(val ps: List<@Contextual Payload>)
+
+    @Serializer(forClass = Payload::class)
+    object PayloadSerializer
+
+    object BinaryPayloadSerializer : KSerializer<Payload> {
+        override val descriptor: SerialDescriptor = PrimitiveSerialDescriptor("BinaryPayload", PrimitiveKind.STRING)
+
+        override fun serialize(encoder: Encoder, value: Payload) {
+            encoder.encodeString(InternalHexConverter.printHexBinary(value.s.encodeToByteArray()))
+        }
+
+        override fun deserialize(decoder: Decoder): Payload {
+            return Payload(InternalHexConverter.parseHexBinary(decoder.decodeString()).decodeToString())
+        }
+    }
+
+    private val value = EnhancedData(Data(100500), Payload("string"), Payload("binary"))
+    private lateinit var json: Json
+
+    @BeforeTest
+    fun initContext() {
+        val scope = serializersModuleOf(Payload::class, PayloadSerializer)
+        val bPolymorphicModule = SerializersModule { polymorphic(Any::class) { subclass(PayloadSerializer) } }
+        json = Json {
+            useArrayPolymorphism = true
+            encodeDefaults = true
+            serializersModule = scope + bPolymorphicModule
+        }
+    }
+
+    @Test
+    fun testWriteCustom() {
+        val s = json.encodeToString(EnhancedData.serializer(), value)
+        assertEquals("""{"data":{"a":100500,"b":42},"stringPayload":{"s":"string"},"binaryPayload":"62696E617279"}""", s)
+    }
+
+    @Test
+    fun testReadCustom() {
+        val s = json.decodeFromString(
+            EnhancedData.serializer(),
+            """{"data":{"a":100500,"b":42},"stringPayload":{"s":"string"},"binaryPayload":"62696E617279"}""")
+        assertEquals(value, s)
+    }
+
+    @Test
+    fun testWriteCustomList() {
+        val s = json.encodeToString(PayloadList.serializer(), PayloadList(listOf(Payload("1"), Payload("2"))))
+        assertEquals("""{"ps":[{"s":"1"},{"s":"2"}]}""", s)
+    }
+
+    @Test
+    fun testPolymorphicResolve() {
+        val map = mapOf<String, Any>("Payload" to Payload("data"))
+        val serializer = MapSerializer(String.serializer(), PolymorphicSerializer(Any::class))
+        val s = json.encodeToString(serializer, map)
+        assertEquals("""{"Payload":["Payload",{"s":"data"}]}""", s)
+    }
+
+    @Test
+    fun testDifferentRepresentations() {
+        val simpleModule = serializersModuleOf(PayloadSerializer)
+        val binaryModule = serializersModuleOf(BinaryPayloadSerializer)
+
+        val json1 = Json { useArrayPolymorphism = true; serializersModule = simpleModule }
+        val json2 = Json { useArrayPolymorphism = true; serializersModule = binaryModule }
+
+        // in json1, Payload would be serialized with PayloadSerializer,
+        // in json2, Payload would be serialized with BinaryPayloadSerializer
+
+        val list = PayloadList(listOf(Payload("string")))
+        assertEquals("""{"ps":[{"s":"string"}]}""", json1.encodeToString(PayloadList.serializer(), list))
+        assertEquals("""{"ps":["737472696E67"]}""", json2.encodeToString(PayloadList.serializer(), list))
+    }
+
+    private fun SerialDescriptor.inContext(module: SerializersModule): SerialDescriptor = when (kind) {
+        SerialKind.CONTEXTUAL -> requireNotNull(module.getContextualDescriptor(this)) { "Expected $this to be registered in module" }
+        else -> error("Expected this function to be called on CONTEXTUAL descriptor")
+    }
+
+    @Test
+    fun testResolveContextualDescriptor() {
+        val simpleModule = serializersModuleOf(PayloadSerializer)
+        val binaryModule = serializersModuleOf(BinaryPayloadSerializer)
+
+        val contextDesc = EnhancedData.serializer().descriptor.elementDescriptors.toList()[1] // @ContextualSer stringPayload
+        assertEquals(SerialKind.CONTEXTUAL, contextDesc.kind)
+        assertEquals(0, contextDesc.elementsCount)
+
+        val resolvedToDefault = contextDesc.inContext(simpleModule)
+        assertEquals(StructureKind.CLASS, resolvedToDefault.kind)
+        assertEquals("Payload", resolvedToDefault.serialName)
+        assertEquals(1, resolvedToDefault.elementsCount)
+
+        val resolvedToBinary = contextDesc.inContext(binaryModule)
+        assertEquals(PrimitiveKind.STRING, resolvedToBinary.kind)
+        assertEquals("BinaryPayload", resolvedToBinary.serialName)
+    }
+
+    @Test
+    fun testContextualSerializerUsesDefaultIfModuleIsEmpty() {
+        val s = Json { useArrayPolymorphism = true; encodeDefaults = true }.encodeToString(EnhancedData.serializer(), value)
+        assertEquals("""{"data":{"a":100500,"b":42},"stringPayload":{"s":"string"},"binaryPayload":"62696E617279"}""", s)
+    }
+}