1 files changed, 100 insertions, 0 deletions
diff --git a/core/commonTest/src/kotlinx/serialization/SerializersLookupNamedCompanionTest.kt b/core/commonTest/src/kotlinx/serialization/SerializersLookupNamedCompanionTest.kt
new file mode 100644
index 00000000..65324c4c
--- /dev/null
+++ b/core/commonTest/src/kotlinx/serialization/SerializersLookupNamedCompanionTest.kt
@@ -0,0 +1,100 @@
+/*
+ * Copyright 2017-2023 JetBrains s.r.o. Use of this source code is governed by the Apache 2.0 license.
+ */
+
+@file:Suppress("RUNTIME_ANNOTATION_NOT_SUPPORTED")
+
+package kotlinx.serialization
+
+import kotlinx.serialization.builtins.*
+import kotlinx.serialization.descriptors.*
+import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
+import kotlinx.serialization.encoding.*
+import kotlinx.serialization.internal.*
+import kotlinx.serialization.test.*
+import kotlin.reflect.*
+import kotlin.test.*
+
+class SerializersLookupNamedCompanionTest {
+    @Serializable
+    class Plain(val i: Int) {
+        companion object Named
+    }
+
+    @Serializable
+    class Parametrized<T>(val value: T) {
+        companion object Named
+    }
+
+
+    @Serializer(forClass = PlainWithCustom::class)
+    object PlainSerializer
+
+    @Serializable(PlainSerializer::class)
+    class PlainWithCustom(val i: Int) {
+        companion object Named
+    }
+
+    class ParametrizedSerializer<T : Any>(val serializer: KSerializer<T>) : KSerializer<ParametrizedWithCustom<T>> {
+        override val descriptor: SerialDescriptor =
+            PrimitiveSerialDescriptor("parametrized (${serializer.descriptor})", PrimitiveKind.STRING)
+
+        override fun deserialize(decoder: Decoder): ParametrizedWithCustom<T> = TODO("Not yet implemented")
+        override fun serialize(encoder: Encoder, value: ParametrizedWithCustom<T>) = TODO("Not yet implemented")
+    }
+
+    @Serializable(ParametrizedSerializer::class)
+    class ParametrizedWithCustom<T>(val i: T) {
+        companion object Named
+    }
+
+    @Serializable
+    sealed interface SealedInterface {
+        companion object Named
+    }
+
+    @Serializable
+    sealed interface SealedInterfaceWithExplicitAnnotation {
+        @NamedCompanion
+        companion object Named
+    }
+
+
+    @Test
+    fun test() {
+        assertSame<KSerializer<*>>(Plain.serializer(), serializer(typeOf<Plain>()))
+
+        shouldFail<SerializationException>(beforeKotlin = "1.9.20", onJs = false, onNative = false, onWasm = false) {
+            assertSame<KSerializer<*>>(PlainSerializer, serializer(typeOf<PlainWithCustom>()))
+        }
+
+        shouldFail<SerializationException>(beforeKotlin = "1.9.20", onJs = false, onNative = false, onWasm = false) {
+            assertEquals(
+                Parametrized.serializer(Int.serializer()).descriptor.toString(),
+                serializer(typeOf<Parametrized<Int>>()).descriptor.toString()
+            )
+        }
+
+        shouldFail<SerializationException>(beforeKotlin = "1.9.20", onJs = false, onNative = false, onWasm = false) {
+            assertEquals(
+                ParametrizedWithCustom.serializer(Int.serializer()).descriptor.toString(),
+                serializer(typeOf<ParametrizedWithCustom<Int>>()).descriptor.toString()
+            )
+        }
+
+        shouldFail<SerializationException>(beforeKotlin = "1.9.20", onJs = false, onNative = false, onWasm = false) {
+            assertEquals(
+                SealedInterface.serializer().descriptor.toString(),
+                serializer(typeOf<SealedInterface>()).descriptor.toString()
+            )
+        }
+
+        // should fail because annotation @NamedCompanion will be placed again by the compilation plugin
+        // and they both will be placed into @Container annotation - thus they will be invisible to the runtime
+        shouldFail<SerializationException>(sinceKotlin = "1.9.20", onJs = false, onNative = false, onWasm = false) {
+            serializer(typeOf<SealedInterfaceWithExplicitAnnotation>())
+        }
+    }
+
+
+}
+\ No newline at end of file