packages/flutter/test/widgets/semantics_6_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/widgets.dart';
import 'package:flutter_test/flutter_test.dart';

import 'semantics_tester.dart';

void main() {
  testWidgets('can change semantics in a branch blocked by BlockSemantics', (WidgetTester tester) async {
    final SemanticsTester semantics = SemanticsTester(tester);

    final TestSemantics expectedSemantics = TestSemantics.root(
      children: <TestSemantics>[
        TestSemantics.rootChild(
          id: 1,
          label: 'hello',
          textDirection: TextDirection.ltr,
          rect: TestSemantics.fullScreen,
        ),
      ],
    );

    await tester.pumpWidget(buildWidget(
      blockedText: 'one',
    ));

    expect(semantics, hasSemantics(expectedSemantics));

    // The purpose of the test is to ensure that this change does not throw.
    await tester.pumpWidget(buildWidget(
        blockedText: 'two',
    ));

    expect(semantics, hasSemantics(expectedSemantics));

    // Ensure that the previously blocked semantics end up in the tree correctly when unblocked.
    await tester.pumpWidget(buildWidget(
      blockedText: 'two',
      blocking: false,
    ));
    expect(semantics, includesNodeWith(label: 'two', textDirection: TextDirection.ltr));

    semantics.dispose();
  });
}

Widget buildWidget({ required String blockedText, bool blocking = true }) {
  assert(blockedText != null);
  return Directionality(
    textDirection: TextDirection.ltr,
    child: Stack(
        fit: StackFit.expand,
        children: <Widget>[
          Semantics(
            container: true,
            child: ListView(
              children: <Widget>[
                Text(blockedText),
              ],
            ),
          ),
          BlockSemantics(
            blocking: blocking,
            child: Semantics(
              label: 'hello',
              container: true,
            ),
          ),
        ],
    ),
  );
}