Add a (failing) test for contextual serializers usage

Author: dkhalanskyjb

serialization/common/test/ContextualSerializationTest.kt

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2019-2021 JetBrains s.r.o.
+ * Use of this source code is governed by the Apache 2.0 License that can be found in the LICENSE.txt file.
+ */
+
+package kotlinx.datetime.serialization.test
+
+import kotlinx.datetime.*
+import kotlinx.datetime.serializers.*
+import kotlinx.serialization.Contextual
+import kotlinx.serialization.Serializable
+import kotlinx.serialization.decodeFromString
+import kotlinx.serialization.encodeToString
+import kotlinx.serialization.json.Json
+import kotlinx.serialization.modules.SerializersModule
+import kotlinx.serialization.modules.contextual
+import kotlin.test.Test
+import kotlin.test.assertEquals
+
+class ContextualSerializationTest {
+
+    @Serializable
+    data class Dummy(
+        @Contextual val instant: Instant,
+        @Contextual val date: LocalDate,
+        @Contextual val dateTime: LocalDateTime,
+        @Contextual val datePeriod: DatePeriod,
+        @Contextual val dateTimePeriod: DateTimePeriod,
+        )
+
+    private val module = SerializersModule {
+        contextual(InstantComponentSerializer)
+        contextual(LocalDateComponentSerializer)
+        contextual(LocalDateTimeComponentSerializer)
+        contextual(DatePeriodComponentSerializer)
+        contextual(DateTimePeriodComponentSerializer)
+    }
+
+    private val format = Json { serializersModule = module }
+
+    @Test
+    fun testContextualSerialization() {
+        val dummyValue = Dummy(
+            Instant.parse("2021-03-24T01:29:30.123456789Z"),
+            LocalDate.parse("2020-01-02"),
+            LocalDateTime.parse("2020-01-03T12:59:58.010203045"),
+            DatePeriod.parse("P20Y-2M-3D"),
+            DateTimePeriod.parse("-P50Y-1M-2DT3H4M5.0123S"),
+        )
+        val json = """{"instant":{"epochSeconds":1616549370,"nanosecondsOfSecond":123456789},""" +
+                """"date":{"year":2020,"month":1,"day":2},""" +
+                """"dateTime":{"year":2020,"month":1,"day":3,"hour":12,"minute":59,"second":58,"nanosecond":10203045},""" +
+                """"datePeriod":{"years":19,"months":10,"days":-3},"dateTimePeriod":"P-49Y-11M2DT-3H-4M-5.012300000S"}"""
+        assertEquals(json, format.encodeToString(dummyValue))
+        assertEquals(dummyValue, format.decodeFromString(json))
+    }
+}