examples/api/test/material/appbar/app_bar.3_test.dart

// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';
import 'package:flutter_api_samples/material/app_bar/app_bar.3.dart' as example;
import 'package:flutter_test/flutter_test.dart';

void main() {
  testWidgets(
    'AppBar elevates when nested scroll view is scrolled underneath the AppBar',
    (WidgetTester tester) async {
      Material getMaterial() => tester.widget<Material>(find.descendant(
        of: find.byType(AppBar),
        matching: find.byType(Material),
      ));

      await tester.pumpWidget(
        const example.AppBarApp(),
      );

      // Starts with the base elevation.
      expect(getMaterial().elevation, 0.0);

      await tester.fling(find.text('Beach 3'), const Offset(0.0, -600.0), 2000.0);
      await tester.pumpAndSettle();

      // After scrolling it should be the scrolledUnderElevation.
      expect(getMaterial().elevation, 4.0);
  });
}