Added tests on support of local serializable classes (Kotlin#1532)

Author: shanshin

formats/json/commonTest/src/kotlinx/serialization/features/LocalClassesTest.kt

@@ -0,0 +1,93 @@
+package kotlinx.serialization.features
+
+import kotlinx.serialization.*
+import kotlinx.serialization.descriptors.PrimitiveKind
+import kotlinx.serialization.descriptors.SerialDescriptor
+import kotlinx.serialization.descriptors.buildSerialDescriptor
+import kotlinx.serialization.encoding.Decoder
+import kotlinx.serialization.encoding.Encoder
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.test.jvmOnly
+import kotlinx.serialization.test.noLegacyJs
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class LocalClassesTest {
+    object ObjectCustomSerializer: KSerializer<Any?> {
+        override val descriptor: SerialDescriptor = buildSerialDescriptor("tmp", PrimitiveKind.INT)
+        override fun serialize(encoder: Encoder, value: Any?) {
+            encoder.encodeNull()
+        }
+
+        override fun deserialize(decoder: Decoder): Any? {
+            return decoder.decodeNull()
+        }
+    }
+
+    class ClassCustomSerializer: KSerializer<Any?> {
+        override val descriptor: SerialDescriptor = buildSerialDescriptor("tmp", PrimitiveKind.INT)
+        override fun serialize(encoder: Encoder, value: Any?) {
+            encoder.encodeNull()
+        }
+
+        override fun deserialize(decoder: Decoder): Any? {
+            return decoder.decodeNull()
+        }
+    }
+
+    @Test
+    fun testGeneratedSerializer() {
+        @Serializable
+        data class Local(val i: Int)
+
+        val origin = Local(42)
+
+        noLegacyJs {
+            val decoded: Local = Json.decodeFromString(Json.encodeToString(origin))
+            assertEquals(origin, decoded)
+        }
+    }
+
+    @Test
+    fun testInLambda() {
+        42.let {
+            @Serializable
+            data class Local(val i: Int)
+
+            val origin = Local(it)
+
+            noLegacyJs {
+                val decoded: Local = Json.decodeFromString(Json.encodeToString(origin))
+                assertEquals(origin, decoded)
+            }
+        }
+    }
+
+    @Test
+    fun testObjectCustomSerializer() {
+        @Serializable(with = ObjectCustomSerializer::class)
+        data class Local(val i: Int)
+
+        val origin: Local? = null
+
+        noLegacyJs {
+            val decoded: Local? = Json.decodeFromString(Json.encodeToString(origin))
+            assertEquals(origin, decoded)
+        }
+    }
+
+    @Test
+    fun testClassCustomSerializer() {
+        @Serializable(with = ClassCustomSerializer::class)
+        data class Local(val i: Int)
+
+        val origin: Local? = null
+
+        // FIXME change to `noLegacyJs` when lookup of `ClassCustomSerializer` will work on Native and JS/IR
+        jvmOnly {
+            val decoded: Local? = Json.decodeFromString(Json.encodeToString(origin))
+            assertEquals(origin, decoded)
+        }
+    }
+
+}