feat(app): 完善播放协议搜索与空状态

test/player/player_double_tap_hearts_test.dart

@@ -0,0 +1,29 @@
+// Author: fruit.com.cn
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:fruitshorts/pages/player/widgets/player_double_tap_hearts.dart';
+
+void main() {
+  testWidgets('should_show_three_medium_hearts_when_double_tap_burst_starts', (
+    tester,
+  ) async {
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Scaffold(body: PlayerDoubleTapHeartBurst(onCompleted: _noop)),
+      ),
+    );
+    await tester.pump(const Duration(milliseconds: 160));
+
+    expect(find.byIcon(Icons.favorite_rounded), findsNWidgets(3));
+    expect(_size(tester, 0), 48);
+    expect(_size(tester, 1), 36);
+    expect(_size(tester, 2), 40);
+  });
+}
+
+double _size(WidgetTester tester, int index) {
+  return tester.widget<Icon>(find.byKey(Key('double-tap-heart-$index'))).size!;
+}
+
+void _noop() {}