packages/flutter/test/widgets/parent_data_test.dart

// Copyright 2015 The Chromium 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_test/flutter_test.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';

import 'test_widgets.dart';

class TestParentData {
  TestParentData({ this.top, this.right, this.bottom, this.left });

  final double top;
  final double right;
  final double bottom;
  final double left;
}

void checkTree(WidgetTester tester, List<TestParentData> expectedParentData) {
  final MultiChildRenderObjectElement element = tester.element(
    find.byElementPredicate((Element element) => element is MultiChildRenderObjectElement)
  );
  expect(element, isNotNull);
  expect(element.renderObject is RenderStack, isTrue);
  final RenderStack renderObject = element.renderObject;
  try {
    RenderObject child = renderObject.firstChild;
    for (TestParentData expected in expectedParentData) {
      expect(child is RenderDecoratedBox, isTrue);
      final RenderDecoratedBox decoratedBox = child;
      expect(decoratedBox.parentData is StackParentData, isTrue);
      final StackParentData parentData = decoratedBox.parentData;
      expect(parentData.top, equals(expected.top));
      expect(parentData.right, equals(expected.right));
      expect(parentData.bottom, equals(expected.bottom));
      expect(parentData.left, equals(expected.left));
      final StackParentData decoratedBoxParentData = decoratedBox.parentData;
      child = decoratedBoxParentData.nextSibling;
    }
    expect(child, isNull);
  } catch (e) {
    print(renderObject.toStringDeep());
    rethrow;
  }
}

final TestParentData kNonPositioned = TestParentData();

void main() {
  testWidgets('ParentDataWidget control test', (WidgetTester tester) async {

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: const <Widget>[
          DecoratedBox(decoration: kBoxDecorationA),
          Positioned(
            top: 10.0,
            left: 10.0,
            child: DecoratedBox(decoration: kBoxDecorationB),
          ),
          DecoratedBox(decoration: kBoxDecorationC),
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      kNonPositioned,
      TestParentData(top: 10.0, left: 10.0),
      kNonPositioned,
    ]);

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: const <Widget>[
          Positioned(
            bottom: 5.0,
            right: 7.0,
            child: DecoratedBox(decoration: kBoxDecorationA),
          ),
          Positioned(
            top: 10.0,
            left: 10.0,
            child: DecoratedBox(decoration: kBoxDecorationB),
          ),
          DecoratedBox(decoration: kBoxDecorationC),
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      TestParentData(bottom: 5.0, right: 7.0),
      TestParentData(top: 10.0, left: 10.0),
      kNonPositioned,
    ]);

    const DecoratedBox kDecoratedBoxA = DecoratedBox(decoration: kBoxDecorationA);
    const DecoratedBox kDecoratedBoxB = DecoratedBox(decoration: kBoxDecorationB);
    const DecoratedBox kDecoratedBoxC = DecoratedBox(decoration: kBoxDecorationC);

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: const <Widget>[
          Positioned(
            bottom: 5.0,
            right: 7.0,
            child: kDecoratedBoxA,
          ),
          Positioned(
            top: 10.0,
            left: 10.0,
            child: kDecoratedBoxB,
          ),
          kDecoratedBoxC,
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      TestParentData(bottom: 5.0, right: 7.0),
      TestParentData(top: 10.0, left: 10.0),
      kNonPositioned,
    ]);

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: const <Widget>[
          Positioned(
            bottom: 6.0,
            right: 8.0,
            child: kDecoratedBoxA,
          ),
          Positioned(
            left: 10.0,
            right: 10.0,
            child: kDecoratedBoxB,
          ),
          kDecoratedBoxC,
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      TestParentData(bottom: 6.0, right: 8.0),
      TestParentData(left: 10.0, right: 10.0),
      kNonPositioned,
    ]);

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: <Widget>[
          kDecoratedBoxA,
          Positioned(
            left: 11.0,
            right: 12.0,
            child: Container(child: kDecoratedBoxB),
          ),
          kDecoratedBoxC,
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      kNonPositioned,
      TestParentData(left: 11.0, right: 12.0),
      kNonPositioned,
    ]);

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: <Widget>[
          kDecoratedBoxA,
          Positioned(
            right: 10.0,
            child: Container(child: kDecoratedBoxB),
          ),
          Container(
            child: const Positioned(
              top: 8.0,
              child: kDecoratedBoxC,
            ),
          ),
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      kNonPositioned,
      TestParentData(right: 10.0),
      TestParentData(top: 8.0),
    ]);

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: const <Widget>[
          Positioned(
            right: 10.0,
            child: FlipWidget(left: kDecoratedBoxA, right: kDecoratedBoxB),
          ),
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      TestParentData(right: 10.0),
    ]);

    flipStatefulWidget(tester);
    await tester.pump();

    checkTree(tester, <TestParentData>[
      TestParentData(right: 10.0),
    ]);

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: const <Widget>[
          Positioned(
            top: 7.0,
            child: FlipWidget(left: kDecoratedBoxA, right: kDecoratedBoxB),
          ),
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      TestParentData(top: 7.0),
    ]);

    flipStatefulWidget(tester);
    await tester.pump();

    checkTree(tester, <TestParentData>[
      TestParentData(top: 7.0),
    ]);

    await tester.pumpWidget(
      Stack(textDirection: TextDirection.ltr)
    );

    checkTree(tester, <TestParentData>[]);
  });

  testWidgets('ParentDataWidget conflicting data', (WidgetTester tester) async {
    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: const <Widget>[
          Positioned(
            top: 5.0,
            bottom: 8.0,
            child: Positioned(
              top: 6.0,
              left: 7.0,
              child: DecoratedBox(decoration: kBoxDecorationB),
            ),
          ),
        ],
      ),
    );
    dynamic exception = tester.takeException();
    expect(exception, isFlutterError);
    expect(
      exception.toString(),
      equalsIgnoringHashCodes(
        'Incorrect use of ParentDataWidget.\n'
        'Positioned widgets must be placed directly inside Stack widgets.\n'
        'Positioned(no depth, left: 7.0, top: 6.0, dirty) has a Stack ancestor, but there are other widgets between them:\n'
        '- Positioned(top: 5.0, bottom: 8.0) (this is a different Positioned than the one with the problem)\n'
        'These widgets cannot come between a Positioned and its Stack.\n'
        'The ownership chain for the parent of the offending Positioned was:\n'
        '  Positioned ← Stack ← [root]'
      ),
    );

    await tester.pumpWidget(Stack(textDirection: TextDirection.ltr));

    checkTree(tester, <TestParentData>[]);

    await tester.pumpWidget(
      Container(
        child: Row(
          children: const <Widget>[
            Positioned(
              top: 6.0,
              left: 7.0,
              child: DecoratedBox(decoration: kBoxDecorationB),
            ),
          ],
        ),
      ),
    );
    exception = tester.takeException();
    expect(exception, isFlutterError);
    expect(
      exception.toString(),
      equalsIgnoringHashCodes(
        'Incorrect use of ParentDataWidget.\n'
        'Positioned widgets must be placed inside Stack widgets.\n'
        'Positioned(no depth, left: 7.0, top: 6.0, dirty) has no Stack ancestor at all.\n'
        'The ownership chain for the parent of the offending Positioned was:\n'
        '  Row ← Container ← [root]'
      )
    );

    await tester.pumpWidget(
      Stack(textDirection: TextDirection.ltr)
    );

    checkTree(tester, <TestParentData>[]);
  });

  testWidgets('ParentDataWidget interacts with global keys', (WidgetTester tester) async {
    final GlobalKey key = GlobalKey();

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: <Widget>[
          Positioned(
            top: 10.0,
            left: 10.0,
            child: DecoratedBox(key: key, decoration: kBoxDecorationA),
          ),
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      TestParentData(top: 10.0, left: 10.0),
    ]);

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: <Widget>[
          Positioned(
            top: 10.0,
            left: 10.0,
            child: DecoratedBox(
              decoration: kBoxDecorationB,
              child: DecoratedBox(key: key, decoration: kBoxDecorationA),
            ),
          ),
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      TestParentData(top: 10.0, left: 10.0),
    ]);

    await tester.pumpWidget(
      Stack(
        textDirection: TextDirection.ltr,
        children: <Widget>[
          Positioned(
            top: 10.0,
            left: 10.0,
            child: DecoratedBox(key: key, decoration: kBoxDecorationA),
          ),
        ],
      ),
    );

    checkTree(tester, <TestParentData>[
      TestParentData(top: 10.0, left: 10.0),
    ]);
  });

  testWidgets('Parent data invalid ancestor', (WidgetTester tester) async {
    await tester.pumpWidget(Row(
      children: <Widget>[
        Stack(
          textDirection: TextDirection.ltr,
          children: <Widget>[
            Expanded(
              child: Container(),
            ),
          ],
        ),
      ],
    ));

    final dynamic exception = tester.takeException();
    expect(exception, isFlutterError);
    expect(
      exception.toString(),
      equalsIgnoringHashCodes(
        'Incorrect use of ParentDataWidget.\n'
        'Expanded widgets must be placed directly inside Flex widgets.\n'
        'Expanded(no depth, flex: 1, dirty) has a Flex ancestor, but there are other widgets between them:\n'
        '- Stack(alignment: AlignmentDirectional.topStart, textDirection: ltr, fit: loose, overflow: clip)\n'
        'These widgets cannot come between a Expanded and its Flex.\n'
        'The ownership chain for the parent of the offending Expanded was:\n'
        '  Stack ← Row ← [root]'
      ),
    );
  });
}