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

void main() {

  Future<void> pumpContainer(WidgetTester tester, Widget child) async {
    await tester.pumpWidget(
      DefaultSelectionStyle(
        selectionColor: Colors.red,
        child: child,
      ),
    );
  }

  testWidgets('updates its registrar and delegate based on the number of selectables', (WidgetTester tester) async {
    final TestSelectionRegistrar registrar = TestSelectionRegistrar();
    final TestContainerDelegate delegate = TestContainerDelegate();
    await pumpContainer(
      tester,
      SelectionContainer(
        registrar: registrar,
        delegate: delegate,
        child: Column(
          children: const <Widget>[
            Text('column1', textDirection: TextDirection.ltr),
            Text('column2', textDirection: TextDirection.ltr),
            Text('column3', textDirection: TextDirection.ltr),
          ],
        ),
      ),
    );
    expect(registrar.selectables.length, 1);
    expect(delegate.selectables.length, 3);
  });

  testWidgets('disabled container', (WidgetTester tester) async {
    final TestSelectionRegistrar registrar = TestSelectionRegistrar();
    final TestContainerDelegate delegate = TestContainerDelegate();
    await pumpContainer(
      tester,
      SelectionContainer(
        registrar: registrar,
        delegate: delegate,
        child: SelectionContainer.disabled(
          child: Column(
            children: const <Widget>[
              Text('column1', textDirection: TextDirection.ltr),
              Text('column2', textDirection: TextDirection.ltr),
              Text('column3', textDirection: TextDirection.ltr),
            ],
          ),
        ),
      ),
    );
    expect(registrar.selectables.length, 0);
    expect(delegate.selectables.length, 0);
  });

  testWidgets('selection container registers itself if there is a selectable child', (WidgetTester tester) async {
    final TestSelectionRegistrar registrar = TestSelectionRegistrar();
    final TestContainerDelegate delegate = TestContainerDelegate();
    await pumpContainer(
      tester,
      SelectionContainer(
        registrar: registrar,
        delegate: delegate,
        child: Column(
        ),
      ),
    );
    expect(registrar.selectables.length, 0);

    await pumpContainer(
      tester,
      SelectionContainer(
        registrar: registrar,
        delegate: delegate,
        child: Column(
          children: const <Widget>[
            Text('column1', textDirection: TextDirection.ltr),
          ],
        ),
      ),
    );
    expect(registrar.selectables.length, 1);

    await pumpContainer(
      tester,
      SelectionContainer(
        registrar: registrar,
        delegate: delegate,
        child: Column(
        ),
      ),
    );
    expect(registrar.selectables.length, 0);
  });

  testWidgets('selection container gets registrar from context if not provided', (WidgetTester tester) async {
    final TestSelectionRegistrar registrar = TestSelectionRegistrar();
    final TestContainerDelegate delegate = TestContainerDelegate();

    await pumpContainer(
      tester,
      SelectionRegistrarScope(
        registrar: registrar,
        child: SelectionContainer(
          delegate: delegate,
          child: Column(
            children: const <Widget>[
              Text('column1', textDirection: TextDirection.ltr),
            ],
          ),
        ),
      ),
    );
    expect(registrar.selectables.length, 1);
  });
}

class TestContainerDelegate extends MultiSelectableSelectionContainerDelegate {
  @override
  SelectionResult dispatchSelectionEventToChild(Selectable selectable, SelectionEvent event) {
    throw UnimplementedError();
  }

  @override
  void ensureChildUpdated(Selectable selectable) {
    throw UnimplementedError();
  }
}

class TestSelectionRegistrar extends SelectionRegistrar {
  final Set<Selectable> selectables = <Selectable>{};

  @override
  void add(Selectable selectable) => selectables.add(selectable);

  @override
  void remove(Selectable selectable) => selectables.remove(selectable);
}