fix(home): 首切频道预取并保留播放画面

test/home/k28_a_navigation_test.dart

@@ -1,12 +1,16 @@
 // Author: fruit.com.cn
 
+import 'dart:async';
+
 import 'package:flutter/material.dart';
 import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:fruitshorts/app.dart';
+import 'package:fruitshorts/core/data/models/feed_page.dart';
 import 'package:fruitshorts/core/data/repositories/favorite_repository.dart';
 import 'package:fruitshorts/core/data/repositories/playback_repository.dart';
 import 'package:fruitshorts/core/data/repositories/watch_history_repository.dart';
+import 'package:fruitshorts/pages/home/home_feed_channel.dart';
 import 'package:fruitshorts/pages/player/player_view.dart';
 import 'package:shared_preferences_platform_interface/in_memory_shared_preferences_async.dart';
 import 'package:shared_preferences_platform_interface/shared_preferences_async_platform_interface.dart';
@@ -130,6 +134,44 @@ void main() {
     expect(find.byKey(const Key('home-feed-title')), findsOneWidget);
   });
 
+  testWidgets('should_keep_player_when_first_anime_switch_is_loading', (
+    tester,
+  ) async {
+    final catalog = _PendingAnimeCatalog();
+    await _pumpApp(tester, catalog: catalog);
+    for (var attempt = 0; attempt < 5 && catalog.animeCalls == 0; attempt++) {
+      await tester.pump();
+    }
+    expect(catalog.animeCalls, 1);
+
+    await tester.tap(find.byKey(const Key('home-feed-tab-anime')));
+    await tester.pump();
+
+    expect(find.byType(PlayerPage), findsOneWidget);
+    expect(find.byKey(const Key('home-feed-channel-loading')), findsOneWidget);
+
+    catalog.anime.complete(FeedPage(dramas: [demoDramas[1]]));
+    await tester.pumpAndSettle();
+
+    expect(find.byKey(const Key('home-feed-channel-loading')), findsNothing);
+    expect(
+      tester.widget<PlayerPage>(find.byType(PlayerPage)).feedChannel,
+      HomeFeedChannel.anime,
+    );
+  });
+
+  testWidgets('should_show_empty_state_when_anime_has_no_dramas', (
+    tester,
+  ) async {
+    await _pumpApp(tester, catalog: _EmptyAnimeCatalog());
+
+    await tester.tap(find.byKey(const Key('home-feed-tab-anime')));
+    await tester.pumpAndSettle();
+
+    expect(find.byType(PlayerPage), findsNothing);
+    expect(find.text('No stories available yet.'), findsOneWidget);
+  });
+
   testWidgets('should_refresh_feed_without_blank_loading', (tester) async {
     await _pumpApp(tester);
 
@@ -446,19 +488,20 @@ bool _hasLightStatusBar(WidgetTester tester) => tester
 Future<void> _pumpApp(
   WidgetTester tester, {
   Size size = const Size(390, 844),
+  FakeCatalogRepository? catalog,
 }) async {
   tester.view.physicalSize = size;
   tester.view.devicePixelRatio = 1;
   addTearDown(tester.view.resetPhysicalSize);
   addTearDown(tester.view.resetDevicePixelRatio);
-  final catalog = FakeCatalogRepository();
+  final repository = catalog ?? FakeCatalogRepository();
   await tester.pumpWidget(
     LumaDramaApp(
       playerFactory: createWidgetPlayer,
-      catalogRepository: catalog,
-      categoryRepository: FakeCategoryRepository(catalog: catalog),
+      catalogRepository: repository,
+      categoryRepository: FakeCategoryRepository(catalog: repository),
       watchHistoryRepository: InMemoryWatchHistoryRepository(),
-      favoriteRepository: InMemoryFavoriteRepository(cards: catalog.dramas),
+      favoriteRepository: InMemoryFavoriteRepository(cards: repository.dramas),
       playbackRepository: FakePlaybackRepository(),
       commentRepository: FakeCommentRepository(),
       interactionRepository: FakeInteractionRepository(),
@@ -467,3 +510,35 @@ Future<void> _pumpApp(
   );
   await tester.pumpAndSettle();
 }
+
+class _PendingAnimeCatalog extends FakeCatalogRepository {
+  final anime = Completer<FeedPage>();
+  int animeCalls = 0;
+
+  @override
+  Future<FeedPage> fetchFeed({
+    List<String> types = const [],
+    String? cursor,
+    int size = 10,
+  }) {
+    if (types.contains('ANIME')) {
+      animeCalls++;
+      return anime.future;
+    }
+    return super.fetchFeed(types: types, cursor: cursor, size: size);
+  }
+}
+
+class _EmptyAnimeCatalog extends FakeCatalogRepository {
+  @override
+  Future<FeedPage> fetchFeed({
+    List<String> types = const [],
+    String? cursor,
+    int size = 10,
+  }) {
+    if (types.contains('ANIME')) {
+      return Future.value(const FeedPage(dramas: []));
+    }
+    return super.fetchFeed(types: types, cursor: cursor, size: size);
+  }
+}