fix decoding null

Author: nbransby

build.gradle.kts

@@ -18,7 +18,7 @@ buildscript {
         }
     }
     dependencies {
-        classpath("com.android.tools.build:gradle:4.1.2")
+        classpath("com.android.tools.build:gradle:4.0.2")
         classpath("com.adarshr:gradle-test-logger-plugin:2.1.1")
     }
 }

firebase-common/src/commonMain/kotlin/dev/gitlive/firebase/decoders.kt

@@ -60,8 +60,7 @@ class FirebaseDecoder(internal val value: Any?, private val decodeDouble: (value
     override fun decodeNull() = decodeNull(value)
 
     @ExperimentalSerializationApi
-    override fun decodeInline(inlineDescriptor: SerialDescriptor): Decoder =
-        FirebaseDecoder(value, decodeDouble)
+    override fun decodeInline(inlineDescriptor: SerialDescriptor) = FirebaseDecoder(value, decodeDouble)
 }
 
 class FirebaseClassDecoder(
@@ -79,13 +78,6 @@ class FirebaseClassDecoder(
             .firstOrNull { !descriptor.isElementOptional(it) || containsKey(descriptor.getElementName(it)) }
             ?.also { index = it + 1 }
             ?: DECODE_DONE
-
-    override fun <T : Any> decodeNullableSerializableElement(
-        descriptor: SerialDescriptor,
-        index: Int,
-        deserializer: DeserializationStrategy<T?>,
-        previousValue: T?
-    ) = decodeSerializableElement(descriptor, index, deserializer, previousValue)
 }
 
 open class FirebaseCompositeDecoder constructor(
@@ -123,13 +115,15 @@ open class FirebaseCompositeDecoder constructor(
 
     override fun decodeLongElement(descriptor: SerialDescriptor, index: Int) = decodeLong(get(descriptor, index))
 
-    @ExperimentalSerializationApi
     override fun <T : Any> decodeNullableSerializableElement(
         descriptor: SerialDescriptor,
         index: Int,
         deserializer: DeserializationStrategy<T?>,
         previousValue: T?
-    ) = decodeSerializableElement(descriptor, index, deserializer, previousValue)
+    ): T? {
+        val isNullabilitySupported = deserializer.descriptor.isNullable
+        return if (isNullabilitySupported || decodeNotNullMark(get(descriptor, index))) decodeSerializableElement(descriptor, index, deserializer, previousValue) else decodeNull(get(descriptor, index))
+    }
 
     override fun decodeShortElement(descriptor: SerialDescriptor, index: Int) = decodeShort(get(descriptor, index))
 
@@ -206,5 +200,4 @@ private fun decodeNotNullMark(value: Any?) = value != null
 
 private fun decodeNull(value: Any?) = value as Nothing?
 
-private fun decodeUnit(value: Any?) = value as Unit
 

firebase-common/src/commonTest/kotlin/dev/gitlive/firebase/EncodersTest.kt

@@ -8,6 +8,7 @@ import kotlinx.serialization.Serializable
 import kotlinx.serialization.builtins.ListSerializer
 import kotlin.test.Test
 import kotlin.test.assertEquals
+import kotlin.test.assertNull
 
 expect fun nativeMapOf(vararg pairs: Pair<String, Any>): Any
 expect fun nativeListOf(vararg elements: Any): Any
@@ -47,4 +48,10 @@ class EncodersTest {
         val decoded = decode(ListSerializer(TestData.serializer()), nativeListOf(nativeMapOf("map" to nativeMapOf("key" to "value"))))
         assertEquals(listOf(TestData(mapOf("key" to "value"), false)), decoded)
     }
+
+    @Test
+    fun decodeObjectNullableValue() {
+        val decoded = decode(TestData.serializer(), mapOf("map" to mapOf("key" to "value"), "nullableBool" to null))
+        assertNull(decoded.nullableBool)
+    }
 }