fix(flutter): 修复 iOS 视频首帧闪屏

test/player/player_video_surface_test.dart

@@ -0,0 +1,114 @@
+// Author: fruit.com.cn
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:video_player/video_player.dart';
+
+import 'package:fruitshorts/pages/player/widgets/player_video_surface.dart';
+
+void main() {
+  testWidgets('should_keep_fallback_visible_before_video_is_ready', (
+    tester,
+  ) async {
+    await _pumpSurface(tester);
+
+    expect(find.byKey(const Key('player-fallback-background')), findsOneWidget);
+    expect(find.byKey(const Key('player-fallback-cover')), findsOneWidget);
+    expect(_opacity(tester), 0);
+    expect(
+      tester.widget<Text>(find.byKey(const Key('player-debug-video'))).data,
+      'loading',
+    );
+  });
+
+  testWidgets('should_fade_video_in_within_200ms_after_first_frame', (
+    tester,
+  ) async {
+    final controller = await _pumpSurface(tester);
+    expect(_opacity(tester), 0);
+
+    controller.value = const VideoPlayerValue(
+      duration: Duration(minutes: 1),
+      size: Size(1280, 720),
+      position: Duration(milliseconds: 1),
+      isInitialized: true,
+      isPlaying: true,
+    );
+    await tester.pump();
+
+    expect(_opacity(tester), 1);
+    expect(
+      tester
+          .widget<AnimatedOpacity>(
+            find.byKey(const Key('player-video-opacity')),
+          )
+          .duration,
+      const Duration(milliseconds: 200),
+    );
+    await tester.pump(const Duration(milliseconds: 100));
+    final halfway = _fadeValue(tester);
+    expect(halfway, greaterThan(0));
+    expect(halfway, lessThan(1));
+    await tester.pump(const Duration(milliseconds: 100));
+    expect(_fadeValue(tester), 1);
+    expect(find.byKey(const Key('player-fallback-background')), findsOneWidget);
+  });
+
+  testWidgets('should_show_video_error_above_retained_fallback', (
+    tester,
+  ) async {
+    await _pumpSurface(
+      tester,
+      value: const VideoPlayerValue.erroneous('No route to host'),
+    );
+
+    expect(find.byKey(const Key('player-video-error')), findsOneWidget);
+    expect(find.text('No route to host'), findsOneWidget);
+    expect(find.byKey(const Key('player-fallback-background')), findsOneWidget);
+    expect(_opacity(tester), 0);
+    expect(
+      tester.widget<Text>(find.byKey(const Key('player-debug-video'))).data,
+      'error: No route to host',
+    );
+  });
+}
+
+Future<VideoPlayerController> _pumpSurface(
+  WidgetTester tester, {
+  VideoPlayerValue? value,
+}) async {
+  final controller = VideoPlayerController.networkUrl(
+    Uri.parse('http://192.168.31.187:8081/files/video.mp4'),
+  );
+  addTearDown(controller.dispose);
+  if (value != null) controller.value = value;
+  await tester.pumpWidget(
+    MaterialApp(
+      home: Scaffold(
+        body: PlayerVideoSurface(
+          controller: controller,
+          posterUrl: '/files/poster.jpg',
+          videoUrl: controller.dataSource,
+          theater: false,
+          onTap: () {},
+        ),
+      ),
+    ),
+  );
+  await tester.pump();
+  return controller;
+}
+
+double _opacity(WidgetTester tester) {
+  return tester
+      .widget<AnimatedOpacity>(find.byKey(const Key('player-video-opacity')))
+      .opacity;
+}
+
+double _fadeValue(WidgetTester tester) {
+  final fade = find.descendant(
+    of: find.byKey(const Key('player-video-opacity')),
+    matching: find.byType(FadeTransition),
+  );
+  return tester.widget<FadeTransition>(fade).opacity.value;
+}