Merge pull request #1496 from Jaehwa-Noh/api-21

Add api 21 into CI

core/network/src/main/kotlin/com/google/samples/apps/nowinandroid/core/network/demo/DemoNiaNetworkDataSource.kt

@@ -17,6 +17,8 @@
 package com.google.samples.apps.nowinandroid.core.network.demo
 
 import JvmUnitTestDemoAssetManager
+import android.os.Build.VERSION.SDK_INT
+import android.os.Build.VERSION_CODES.M
 import com.google.samples.apps.nowinandroid.core.network.Dispatcher
 import com.google.samples.apps.nowinandroid.core.network.NiaDispatchers.IO
 import com.google.samples.apps.nowinandroid.core.network.NiaNetworkDataSource
@@ -28,6 +30,7 @@ import kotlinx.coroutines.withContext
 import kotlinx.serialization.ExperimentalSerializationApi
 import kotlinx.serialization.json.Json
 import kotlinx.serialization.json.decodeFromStream
+import java.io.BufferedReader
 import javax.inject.Inject
 
 /**
@@ -39,17 +42,11 @@ class DemoNiaNetworkDataSource @Inject constructor(
     private val assets: DemoAssetManager = JvmUnitTestDemoAssetManager,
 ) : NiaNetworkDataSource {
 
-    @OptIn(ExperimentalSerializationApi::class)
     override suspend fun getTopics(ids: List<String>?): List<NetworkTopic> =
-        withContext(ioDispatcher) {
+        getDataFromJsonFile(TOPICS_ASSET)
-            assets.open(TOPICS_ASSET).use(networkJson::decodeFromStream)
-        }
 
-    @OptIn(ExperimentalSerializationApi::class)
     override suspend fun getNewsResources(ids: List<String>?): List<NetworkNewsResource> =
-        withContext(ioDispatcher) {
+        getDataFromJsonFile(NEWS_ASSET)
-            assets.open(NEWS_ASSET).use(networkJson::decodeFromStream)
-        }
 
     override suspend fun getTopicChangeList(after: Int?): List<NetworkChangeList> =
         getTopics().mapToChangeList(NetworkTopic::id)
@@ -57,6 +54,27 @@ class DemoNiaNetworkDataSource @Inject constructor(
     override suspend fun getNewsResourceChangeList(after: Int?): List<NetworkChangeList> =
         getNewsResources().mapToChangeList(NetworkNewsResource::id)
 
+    /**
+     * Get data from the given JSON [fileName].
+     */
+    @OptIn(ExperimentalSerializationApi::class)
+    private suspend inline fun <reified T> getDataFromJsonFile(fileName: String): List<T> =
+        withContext(ioDispatcher) {
+            assets.open(fileName).use { inputStream ->
+                if (SDK_INT <= M) {
+                    /**
+                     * On API 23 (M) and below we must use a workaround to avoid an exception being
+                     * thrown during deserialization. See:
+                     * https://github.com/Kotlin/kotlinx.serialization/issues/2457#issuecomment-1786923342
+                     */
+                    inputStream.bufferedReader().use(BufferedReader::readText)
+                        .let(networkJson::decodeFromString)
+                } else {
+                    networkJson.decodeFromStream(inputStream)
+                }
+            }
+        }
+
     companion object {
         private const val NEWS_ASSET = "news.json"
         private const val TOPICS_ASSET = "topics.json"