test: add test for cache.

kraken/lib/src/launcher/bundle.dart

@@ -201,7 +201,7 @@ class NetworkAssetBundle extends AssetBundle {
         _additionalHttpHeaders = additionalHttpHeaders,
         httpClient = HttpClient();
 
-  int? contextId;
+  final int? contextId;
   final Uri _baseUrl;
   final HttpClient httpClient;
   final Map<String, String>? _additionalHttpHeaders;

kraken/test/kraken_test.dart

@@ -21,6 +21,8 @@ import 'src/css/values.dart' as css_values;
 
 import 'src/gesture/scroll_physics.dart' as scroll_physics;
 
+import 'src/launcher/bundle.dart' as bundle;
+
 // The main entry for kraken unit test.
 // Setup all common logic.
 void main() {
@@ -64,6 +66,10 @@ void main() {
     scroll_physics.main();
   });
 
+  group('launcher', () {
+    bundle.main();
+  });
+
   tearDownAll(() {
     if (tempDirectory.existsSync()) {
       tempDirectory.deleteSync(recursive: true);

kraken/test/src/launcher/bundle.dart

@@ -0,0 +1,23 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:kraken/launcher.dart';
+import 'package:test/test.dart';
+
+import '../../local_http_server.dart';
+
+void main() {
+  var server = LocalHttpServer.getInstance();
+
+  group('Bundle', () {
+    test('NetworkAssetsBundle basic', () async {
+      Uri uri = server.getUri('js_over_128k');
+      // Using contextId to active cache.
+      var bundle = NetworkAssetBundle(uri, contextId: 1);
+      ByteData data = await bundle.load(uri.toString());
+      var code = utf8.decode(data.buffer.asUint8List(data.offsetInBytes, data.lengthInBytes));
+
+      expect(code.length > 128 * 1024, true);
+    });
+  });
+}