flutter_flutter/packages/flutter/test/widgets/view_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 'dart:ui';

import 'package:flutter/src/widgets/view.dart';
import 'package:flutter/widgets.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  testWidgets('Widgets running with runApp can find View', (WidgetTester tester) async {
    FlutterView? viewOf;
    FlutterView? viewMaybeOf;

    runApp(
      Builder(
        builder: (BuildContext context) {
          viewOf = View.of(context);
          viewMaybeOf = View.maybeOf(context);
          return Container();
        },
      ),
    );

    expect(viewOf, isNotNull);
    expect(viewOf, isA<FlutterView>());
    expect(viewMaybeOf, isNotNull);
    expect(viewMaybeOf, isA<FlutterView>());
  });

  testWidgets('Widgets running with pumpWidget can find View', (WidgetTester tester) async {
    FlutterView? view;
    FlutterView? viewMaybeOf;

    await tester.pumpWidget(
      Builder(
        builder: (BuildContext context) {
          view = View.of(context);
          viewMaybeOf = View.maybeOf(context);
          return Container();
        },
      ),
    );

    expect(view, isNotNull);
    expect(view, isA<FlutterView>());
    expect(viewMaybeOf, isNotNull);
    expect(viewMaybeOf, isA<FlutterView>());
  });

  testWidgets('cannot find View behind a LookupBoundary', (WidgetTester tester) async {
    await tester.pumpWidget(
      LookupBoundary(
        child: Container(),
      ),
    );

    final BuildContext context = tester.element(find.byType(Container));

    expect(View.maybeOf(context), isNull);
    expect(
      () => View.of(context),
      throwsA(isA<FlutterError>().having(
        (FlutterError error) => error.message,
        'message',
        contains('The context provided to View.of() does have a View widget ancestor, but it is hidden by a LookupBoundary.'),
      )),
    );
  });
}