1 files changed, 151 insertions, 0 deletions
diff --git a/formats/json-tests/commonTest/src/kotlinx/serialization/json/AbstractJsonImplicitNullsTest.kt b/formats/json-tests/commonTest/src/kotlinx/serialization/json/AbstractJsonImplicitNullsTest.kt
new file mode 100644
index 00000000..a2f4a9df
--- /dev/null
+++ b/formats/json-tests/commonTest/src/kotlinx/serialization/json/AbstractJsonImplicitNullsTest.kt
@@ -0,0 +1,151 @@
+package kotlinx.serialization.json
+
+import kotlinx.serialization.*
+import kotlin.test.*
+
+/*
+ * Actual testing should be performed in subclasses.
+ * Subclasses implement serialization and deserialization for different types: serial Kotlin classes, JsonElement, dynamic etc
+ */
+@Ignore
+abstract class AbstractJsonImplicitNullsTest {
+    @Serializable
+    data class Nullable(
+        val f0: Int?,
+        val f1: Int?,
+        val f2: Int?,
+        val f3: Int?,
+    )
+
+    @Serializable
+    data class WithNotNull(
+        val f0: Int?,
+        val f1: Int?,
+        val f2: Int,
+    )
+
+    @Serializable
+    data class WithOptional(
+        val f0: Int?,
+        val f1: Int? = 1,
+        val f2: Int = 2,
+    )
+
+    @Serializable
+    data class Outer(val i: Inner)
+
+    @Serializable
+    data class Inner(val s1: String?, val s2: String?)
+
+    @Serializable
+    data class ListWithNullable(val l: List<Int?>)
+
+    @Serializable
+    data class MapWithNullable(val m: Map<Int?, Int?>)
+
+    @Serializable
+    data class NullableList(val l: List<Int>?)
+
+    @Serializable
+    data class NullableMap(val m: Map<Int, Int>?)
+
+
+    private val format = Json { explicitNulls = false }
+
+    protected abstract fun <T> Json.encode(value: T, serializer: KSerializer<T>): String
+
+    protected abstract fun <T> Json.decode(json: String, serializer: KSerializer<T>): T
+
+    @Test
+    fun testExplicit() {
+        val plain = Nullable(null, 10, null, null)
+        val json = """{"f0":null,"f1":10,"f2":null,"f3":null}"""
+
+        assertEquals(json, Json.encode(plain, Nullable.serializer()))
+        assertEquals(plain, Json.decode(json, Nullable.serializer()))
+    }
+
+    @Test
+    fun testNullable() {
+        val plain = Nullable(null, 10, null, null)
+        val json = """{"f1":10}"""
+
+        assertEquals(json, format.encode(plain, Nullable.serializer()))
+        assertEquals(plain, format.decode(json, Nullable.serializer()))
+    }
+
+    @Test
+    fun testMissingNotNull() {
+        val json = """{"f1":10}"""
+
+        assertFailsWith(SerializationException::class) {
+            format.decode(json, WithNotNull.serializer())
+        }
+    }
+
+    @Test
+    fun testDecodeOptional() {
+        val json = """{}"""
+
+        val decoded = format.decode(json, WithOptional.serializer())
+        assertEquals(WithOptional(null), decoded)
+    }
+
+
+    @Test
+    fun testNestedJsonObject() {
+        val json = """{"i": {}}"""
+
+        val decoded = format.decode(json, Outer.serializer())
+        assertEquals(Outer(Inner(null, null)), decoded)
+    }
+
+    @Test
+    fun testListWithNullable() {
+        val jsonWithNull = """{"l":[null]}"""
+        val jsonWithEmptyList = """{"l":[]}"""
+
+        val encoded = format.encode(ListWithNullable(listOf(null)), ListWithNullable.serializer())
+        assertEquals(jsonWithNull, encoded)
+
+        val decoded = format.decode(jsonWithEmptyList, ListWithNullable.serializer())
+        assertEquals(ListWithNullable(emptyList()), decoded)
+    }
+
+    @Test
+    fun testMapWithNullable() {
+        val jsonWithNull = """{"m":{null:null}}"""
+        val jsonWithQuotedNull = """{"m":{"null":null}}"""
+        val jsonWithEmptyList = """{"m":{}}"""
+
+        val encoded = format.encode(MapWithNullable(mapOf(null to null)), MapWithNullable.serializer())
+        //Json encode map null key as `null:` but other external utilities may encode it as a String `"null":`
+        assertTrue { listOf(jsonWithNull, jsonWithQuotedNull).contains(encoded) }
+
+        val decoded = format.decode(jsonWithEmptyList, MapWithNullable.serializer())
+        assertEquals(MapWithNullable(emptyMap()), decoded)
+    }
+
+    @Test
+    fun testNullableList() {
+        val json = """{}"""
+
+        val encoded = format.encode(NullableList(null), NullableList.serializer())
+        assertEquals(json, encoded)
+
+        val decoded = format.decode(json, NullableList.serializer())
+        assertEquals(NullableList(null), decoded)
+    }
+
+    @Test
+    fun testNullableMap() {
+        val json = """{}"""
+
+        val encoded = format.encode(NullableMap(null), NullableMap.serializer())
+        assertEquals(json, encoded)
+
+        val decoded = format.decode(json, NullableMap.serializer())
+        assertEquals(NullableMap(null), decoded)
+    }
+
+}