feat(home): 顶部导航随翻页联动并把推荐更名为精选

test/recommend/home_tab_motion_controller_test.dart

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+// Author: fruit.com.cn
+// 职责：验证首页跨页动画的目标保留、连点打断和减少动画行为。
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:fruitshorts/pages/recommend/home_tab_motion_controller.dart';
+
+const _midpoint = Duration(milliseconds: 90);
+const _finish = Duration(milliseconds: 300);
+
+Widget _pager(HomeTabMotionController controller, List<int> accepted) =>
+    MaterialApp(
+      home: PageView(
+        controller: controller,
+        onPageChanged: (index) {
+          if (controller.acceptsSelection(index)) accepted.add(index);
+        },
+        children: const [
+          ColoredBox(color: Colors.black),
+          ColoredBox(color: Colors.red),
+          ColoredBox(color: Colors.grey),
+        ],
+      ),
+    );
+
+void main() {
+  testWidgets(
+    'should_ignore_intermediate_page_when_clicking_across_two_pages',
+    (tester) async {
+      int? settled;
+      final controller = HomeTabMotionController(
+        onSettled: (index) => settled = index,
+      );
+      addTearDown(controller.dispose);
+      final accepted = <int>[];
+      await tester.pumpWidget(_pager(controller, accepted));
+      final transition = controller.selectPage(2, reduceMotion: false);
+      await tester.pump();
+      await tester.pump(_midpoint);
+      expect(controller.pagePosition, inExclusiveRange(0.0, 2.0));
+      expect(controller.acceptsSelection(1), isFalse);
+      expect(accepted, isNot(contains(1)));
+      await tester.pump(_finish);
+      await transition;
+      expect(controller.pagePosition, 2);
+      expect(settled, 2);
+      expect(controller.acceptsSelection(1), isTrue);
+    },
+  );
+
+  testWidgets('should_keep_last_target_when_clicks_interrupt_each_other', (
+    tester,
+  ) async {
+    int? settled;
+    final controller = HomeTabMotionController(
+      onSettled: (index) => settled = index,
+    );
+    addTearDown(controller.dispose);
+    await tester.pumpWidget(_pager(controller, []));
+    final first = controller.selectPage(2, reduceMotion: false);
+    await tester.pump();
+    await tester.pump(_midpoint);
+    final last = controller.selectPage(0, reduceMotion: false);
+    await tester.pump();
+    expect(controller.acceptsSelection(2), isFalse);
+    await tester.pump(_finish);
+    await Future.wait([first, last]);
+    expect(controller.pagePosition, 0);
+    expect(settled, 0);
+  });
+
+  testWidgets('should_jump_to_target_when_reduced_motion_is_enabled', (
+    tester,
+  ) async {
+    int? settled;
+    final controller = HomeTabMotionController(
+      onSettled: (index) => settled = index,
+    );
+    addTearDown(controller.dispose);
+    await tester.pumpWidget(_pager(controller, []));
+    await controller.selectPage(2, reduceMotion: true);
+    expect(controller.pagePosition, 2);
+    expect(settled, 2);
+  });
+
+  testWidgets('should_release_target_when_user_drag_interrupts_animation', (
+    tester,
+  ) async {
+    final controller = HomeTabMotionController(onSettled: (_) {});
+    addTearDown(controller.dispose);
+    await tester.pumpWidget(_pager(controller, []));
+    final transition = controller.selectPage(2, reduceMotion: false);
+    await tester.pump();
+    await tester.pump(_midpoint);
+    final gesture = await tester.startGesture(
+      tester.getCenter(find.byType(PageView)),
+    );
+    await gesture.moveBy(const Offset(60, 0));
+    await tester.pump();
+    await transition;
+    expect(controller.acceptsSelection(0), isTrue);
+    expect(controller.acceptsSelection(1), isTrue);
+    await gesture.up();
+    await tester.pumpAndSettle();
+  });
+}