packages/unit/test/widget/stack_test.dart

import 'package:sky/widgets.dart';
import 'package:test/test.dart';

import 'widget_tester.dart';

void main() {
  test('Can change position data', () {
    testWidgets((WidgetTester tester) {
      Key key = new Key('container');

      tester.pumpWidget(
        new Stack([
          new Positioned(
            left: 10.0,
            child: new Container(
              key: key,
              width: 10.0,
              height: 10.0
            )
          )
        ])
      );

      Element container = tester.findElementByKey(key);
      expect(container.renderObject.parentData.top, isNull);
      expect(container.renderObject.parentData.right, isNull);
      expect(container.renderObject.parentData.bottom, isNull);
      expect(container.renderObject.parentData.left, equals(10.0));

      tester.pumpWidget(
        new Stack([
          new Positioned(
            right: 10.0,
            child: new Container(
              key: key,
              width: 10.0,
              height: 10.0
            )
          )
        ])
      );

      container = tester.findElementByKey(key);
      expect(container.renderObject.parentData.top, isNull);
      expect(container.renderObject.parentData.right, equals(10.0));
      expect(container.renderObject.parentData.bottom, isNull);
      expect(container.renderObject.parentData.left, isNull);
    });
  });

  test('Can remove parent data', () {
    testWidgets((WidgetTester tester) {
      Key key = new Key('container');
      Container container = new Container(key: key, width: 10.0, height: 10.0);

      tester.pumpWidget(new Stack([ new Positioned(left: 10.0, child: container) ]));
      Element containerElement = tester.findElementByKey(key);

      expect(containerElement.renderObject.parentData.top, isNull);
      expect(containerElement.renderObject.parentData.right, isNull);
      expect(containerElement.renderObject.parentData.bottom, isNull);
      expect(containerElement.renderObject.parentData.left, equals(10.0));

      tester.pumpWidget(new Stack([ container ]));
      containerElement = tester.findElementByKey(key);

      expect(containerElement.renderObject.parentData.top, isNull);
      expect(containerElement.renderObject.parentData.right, isNull);
      expect(containerElement.renderObject.parentData.bottom, isNull);
      expect(containerElement.renderObject.parentData.left, isNull);
    });
  });
}