1 files changed, 44 insertions, 0 deletions
diff --git a/formats/json-tests/jvmTest/src/kotlinx/serialization/SerializerForNullableJavaTypeTest.kt b/formats/json-tests/jvmTest/src/kotlinx/serialization/SerializerForNullableJavaTypeTest.kt
new file mode 100644
index 00000000..ebed6f37
--- /dev/null
+++ b/formats/json-tests/jvmTest/src/kotlinx/serialization/SerializerForNullableJavaTypeTest.kt
@@ -0,0 +1,44 @@
+/*
+ * 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 org.junit.Test
+import java.util.*
+import kotlin.test.*
+
+class SerializerForNullableJavaTypeTest {
+
+    // User-reported generic serialization
+    class DateSerializer : KSerializer<Date?> {
+
+        override val descriptor = PrimitiveSerialDescriptor("LocalTime?", PrimitiveKind.LONG).nullable
+
+        override fun deserialize(decoder: Decoder): Date? = when (val seconds = decoder.decodeLong()) {
+            -1L -> null
+            else -> Date(seconds)
+        }
+
+        override fun serialize(encoder: Encoder, value: Date?) {
+            when (value) {
+                null -> encoder.encodeLong(-1L) //this line is never reached despite that nulls exist in serialized lists
+                else -> encoder.encodeLong(value.toInstant().toEpochMilli())
+            }
+        }
+    }
+
+    @Serializable
+    private data class ListWrapper(val times: List<@Serializable(with = DateSerializer::class) Date?>)
+
+    @Test
+    fun testMixedList() {
+        val data = ListWrapper(listOf(Date(42), null))
+        val str = Json.encodeToString(data)
+        assertEquals("""{"times":[42,-1]}""", str)
+        assertEquals(data, Json.decodeFromString(str))
+    }
+}