flutter/packages/unit/test/widget/parent_data_test.dart

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

import 'test_widgets.dart';
import 'widget_tester.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) {
  MultiChildRenderObjectElement element =
      tester.findElement((Element element) => element is MultiChildRenderObjectElement);
  expect(element, isNotNull);
  expect(element.renderObject is RenderStack, isTrue);
  RenderStack renderObject = element.renderObject;
  try {
    RenderObject child = renderObject.firstChild;
    for (TestParentData expected in expectedParentData) {
      expect(child is RenderDecoratedBox, isTrue);
      RenderDecoratedBox decoratedBox = child;
      expect(decoratedBox.parentData is StackParentData, isTrue);
      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));
      child = (decoratedBox.parentData as StackParentData).nextSibling;
    }
    expect(child, isNull);
  } catch (e) {
    print(renderObject.toStringDeep());
    rethrow;
  }
}

final TestParentData kNonPositioned = new TestParentData();

void main() {
  dynamic cachedException;

  setUp(() {
    assert(cachedException == null);
    debugWidgetsExceptionHandler = (String context, dynamic exception, StackTrace stack) {
      cachedException = exception;
    };
  });

  tearDown(() {
    cachedException = null;
    debugWidgetsExceptionHandler = null;
  });

  test('ParentDataWidget control test', () {
    testWidgets((WidgetTester tester) {

      tester.pumpWidget(
        new Stack(<Widget>[
          new DecoratedBox(decoration: kBoxDecorationA),
          new Positioned(
            top: 10.0,
            left: 10.0,
            child: new DecoratedBox(decoration: kBoxDecorationB)
          ),
          new DecoratedBox(decoration: kBoxDecorationC),
        ])
      );

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

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

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

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

      tester.pumpWidget(
        new Stack(<Widget>[
          new Positioned(
            bottom: 5.0,
            right: 7.0,
            child: kDecoratedBoxA
          ),
          new Positioned(
            top: 10.0,
            left: 10.0,
            child: kDecoratedBoxB
          ),
          kDecoratedBoxC,
        ])
      );

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

      tester.pumpWidget(
        new Stack(<Widget>[
          new Positioned(
            bottom: 6.0,
            right: 8.0,
            child: kDecoratedBoxA
          ),
          new Positioned(
            left: 10.0,
            right: 10.0,
            child: kDecoratedBoxB
          ),
          kDecoratedBoxC,
        ])
      );

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

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

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

      tester.pumpWidget(
        new Stack(<Widget>[
          kDecoratedBoxA,
          new Positioned(
            right: 10.0,
            child: new Container(child: kDecoratedBoxB)
          ),
          new Container(
            child: new Positioned(
              top: 8.0,
              child: kDecoratedBoxC
            )
          )
        ])
      );

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

      tester.pumpWidget(
        new Stack(<Widget>[
          new Positioned(
            right: 10.0,
            child: new FlipComponent(left: kDecoratedBoxA, right: kDecoratedBoxB)
          ),
        ])
      );

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

      flipStatefulComponent(tester);
      tester.pump();

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

      tester.pumpWidget(
        new Stack(<Widget>[
          new Positioned(
            top: 7.0,
            child: new FlipComponent(left: kDecoratedBoxA, right: kDecoratedBoxB)
          ),
        ])
      );

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

      flipStatefulComponent(tester);
      tester.pump();

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

      tester.pumpWidget(
        new Stack(<Widget>[])
      );

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

  test('ParentDataWidget conflicting data', () {
    testWidgets((WidgetTester tester) {
      expect(cachedException, isNull);

      tester.pumpWidget(
        new Stack(<Widget>[
          new Positioned(
            top: 5.0,
            bottom: 8.0,
            child: new Positioned(
              top: 6.0,
              left: 7.0,
              child: new DecoratedBox(decoration: kBoxDecorationB)
            )
          )
        ])
      );

      expect(cachedException, isNotNull);
      cachedException = null;

      tester.pumpWidget(new Stack(<Widget>[]));

      checkTree(tester, <TestParentData>[]);
      expect(cachedException, isNull);

      tester.pumpWidget(
        new Container(
          child: new Flex(<Widget>[
            new Positioned(
              top: 6.0,
              left: 7.0,
              child: new DecoratedBox(decoration: kBoxDecorationB)
            )
          ])
        )
      );

      expect(cachedException, isNotNull);
      cachedException = null;

      tester.pumpWidget(
        new Stack(<Widget>[])
      );

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