packages/flutter/test/semantics/semantics_update_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.

// @dart = 2.8

import 'dart:typed_data';
import 'dart:ui' as ui;

import 'package:flutter/material.dart';
import 'package:flutter_test/flutter_test.dart';

void main() {
  SemanticsUpdateTestBinding();

  testWidgets('Semantics update does not send update for merged nodes.', (WidgetTester tester) async {
    final SemanticsHandle handle = tester.ensureSemantics();
    // Pumps a placeholder to trigger the warm up frame.
    await tester.pumpWidget(
      const Placeholder(),
      // Stops right after the warm up frame.
      null,
      EnginePhase.build
    );
    // The warm up frame will send update for an empty semantics tree. We
    // ignore this one time update.
    SemanticsUpdateBuilderSpy.observations.clear();

    // Builds the real widget tree.
    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: MergeSemantics(
          child: Semantics(
            label: 'outer',
            // This semantics node should not be part of the semantics update
            // because it is under another semantics container.
            child: Semantics(
              label: 'inner',
              container: true,
              child: const Text('text'),
            ),
          ),
        ),
      ),
    );

    expect(SemanticsUpdateBuilderSpy.observations.length, 2);

    expect(SemanticsUpdateBuilderSpy.observations.containsKey(0), isTrue);
    expect(SemanticsUpdateBuilderSpy.observations[0].childrenInTraversalOrder.length, 1);
    expect(SemanticsUpdateBuilderSpy.observations[0].childrenInTraversalOrder[0], 1);

    expect(SemanticsUpdateBuilderSpy.observations.containsKey(1), isTrue);
    expect(SemanticsUpdateBuilderSpy.observations[1].childrenInTraversalOrder.length, 0);
    expect(SemanticsUpdateBuilderSpy.observations[1].label, 'outer\ninner\ntext');

    SemanticsUpdateBuilderSpy.observations.clear();

    // Updates the inner semantics label and verifies it only sends update for
    // the merged parent.
    await tester.pumpWidget(
      Directionality(
        textDirection: TextDirection.ltr,
        child: MergeSemantics(
          child: Semantics(
            label: 'outer',
            // This semantics node should not be part of the semantics update
            // because it is under another semantics container.
            child: Semantics(
              label: 'inner-updated',
              container: true,
              child: const Text('text'),
            ),
          ),
        ),
      ),
    );
    expect(SemanticsUpdateBuilderSpy.observations.length, 1);

    expect(SemanticsUpdateBuilderSpy.observations.containsKey(1), isTrue);
    expect(SemanticsUpdateBuilderSpy.observations[1].childrenInTraversalOrder.length, 0);
    expect(SemanticsUpdateBuilderSpy.observations[1].label, 'outer\ninner-updated\ntext');

    SemanticsUpdateBuilderSpy.observations.clear();
    handle.dispose();
  });
}

class SemanticsUpdateTestBinding extends AutomatedTestWidgetsFlutterBinding {
  @override
  ui.SemanticsUpdateBuilder createSemanticsUpdateBuilder() {
    return SemanticsUpdateBuilderSpy();
  }
}

class SemanticsUpdateBuilderSpy extends ui.SemanticsUpdateBuilder {
  static Map<int, SemanticsNodeUpdateObservation> observations = <int, SemanticsNodeUpdateObservation>{};

  @override
  void updateNode({
    @required int id,
    @required int flags,
    @required int actions,
    @required int maxValueLength,
    @required int currentValueLength,
    @required int textSelectionBase,
    @required int textSelectionExtent,
    @required int platformViewId,
    @required int scrollChildren,
    @required int scrollIndex,
    @required double scrollPosition,
    @required double scrollExtentMax,
    @required double scrollExtentMin,
    @required double elevation,
    @required double thickness,
    @required Rect rect,
    @required String label,
    @required String hint,
    @required String value,
    @required String increasedValue,
    @required String decreasedValue,
    TextDirection textDirection,
    @required Float64List transform,
    @required Int32List childrenInTraversalOrder,
    @required Int32List childrenInHitTestOrder,
    @required Int32List additionalActions,
  }) {
    // Makes sure we don't send the same id twice.
    assert(!observations.containsKey(id));
    observations[id] = SemanticsNodeUpdateObservation(
      id: id,
      flags: flags,
      actions: actions,
      maxValueLength: maxValueLength,
      currentValueLength: currentValueLength,
      textSelectionBase: textSelectionBase,
      textSelectionExtent: textSelectionExtent,
      platformViewId: platformViewId,
      scrollChildren: scrollChildren,
      scrollIndex: scrollIndex,
      scrollPosition: scrollPosition,
      scrollExtentMax: scrollExtentMax,
      scrollExtentMin: scrollExtentMin,
      elevation: elevation,
      thickness: thickness,
      rect: rect,
      label: label,
      hint: hint,
      value: value,
      increasedValue: increasedValue,
      decreasedValue: decreasedValue,
      textDirection: textDirection,
      transform: transform,
      childrenInTraversalOrder: childrenInTraversalOrder,
      childrenInHitTestOrder: childrenInHitTestOrder,
      additionalActions: additionalActions,
    );
  }
}

class SemanticsNodeUpdateObservation {
  const SemanticsNodeUpdateObservation({
    @required this.id,
    @required this.flags,
    @required this.actions,
    @required this.maxValueLength,
    @required this.currentValueLength,
    @required this.textSelectionBase,
    @required this.textSelectionExtent,
    @required this.platformViewId,
    @required this.scrollChildren,
    @required this.scrollIndex,
    @required this.scrollPosition,
    @required this.scrollExtentMax,
    @required this.scrollExtentMin,
    @required this.elevation,
    @required this.thickness,
    @required this.rect,
    @required this.label,
    @required this.hint,
    @required this.value,
    @required this.increasedValue,
    @required this.decreasedValue,
    this.textDirection,
    @required this.transform,
    @required this.childrenInTraversalOrder,
    @required this.childrenInHitTestOrder,
    @required this.additionalActions,
  });

  final int id;
  final int flags;
  final int actions;
  final int maxValueLength;
  final int currentValueLength;
  final int textSelectionBase;
  final int textSelectionExtent;
  final int platformViewId;
  final int scrollChildren;
  final int scrollIndex;
  final double scrollPosition;
  final double scrollExtentMax;
  final double scrollExtentMin;
  final double elevation;
  final double thickness;
  final Rect rect;
  final String label;
  final String hint;
  final String value;
  final String increasedValue;
  final String decreasedValue;
  final TextDirection textDirection;
  final Float64List transform;
  final Int32List childrenInTraversalOrder;
  final Int32List childrenInHitTestOrder;
  final Int32List additionalActions;
}