Migrate sky/tests/layout to sky/unit/test

Also, I've organized the tests by the render object they're testing.

packages/unit/test/rendering/image_test.dart

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+import 'dart:sky' as sky;
+
+import 'package:sky/rendering.dart';
+import 'package:test/test.dart';
+
+import 'layout_utils.dart';
+
+class SquareImage implements sky.Image {
+  int get width => 10;
+  int get height => 10;
+}
+
+class WideImage implements sky.Image {
+  int get width => 20;
+  int get height => 10;
+}
+
+class TallImage implements sky.Image {
+  int get width => 10;
+  int get height => 20;
+}
+
+void main() {
+  test('Image sizing', () {
+    RenderImage image;
+
+    image = new RenderImage(image: new SquareImage());
+    layout(image,
+          constraints: new BoxConstraints(
+              minWidth: 25.0,
+              minHeight: 25.0,
+              maxWidth: 100.0,
+              maxHeight: 100.0));
+    expect(image.size.width, equals(25.0));
+    expect(image.size.height, equals(25.0));
+
+    image = new RenderImage(image: new WideImage());
+    layout(image,
+           constraints: new BoxConstraints(
+              minWidth: 5.0,
+              minHeight: 30.0,
+              maxWidth: 100.0,
+              maxHeight: 100.0));
+    expect(image.size.width, equals(60.0));
+    expect(image.size.height, equals(30.0));
+
+    image = new RenderImage(image: new TallImage());
+    layout(image,
+           constraints: new BoxConstraints(
+              minWidth: 50.0,
+              minHeight: 5.0,
+              maxWidth: 75.0,
+              maxHeight: 75.0));
+    expect(image.size.width, equals(50.0));
+    expect(image.size.height, equals(75.0));
+
+    image = new RenderImage(image: new WideImage());
+    layout(image,
+           constraints: new BoxConstraints(
+              minWidth: 5.0,
+              minHeight: 5.0,
+              maxWidth: 100.0,
+              maxHeight: 100.0));
+    expect(image.size.width, equals(20.0));
+    expect(image.size.height, equals(10.0));
+
+    image = new RenderImage(image: new WideImage());
+    layout(image,
+           constraints: new BoxConstraints(
+              minWidth: 5.0,
+              minHeight: 5.0,
+              maxWidth: 16.0,
+              maxHeight: 16.0));
+    expect(image.size.width, equals(16.0));
+    expect(image.size.height, equals(8.0));
+
+    image = new RenderImage(image: new TallImage());
+    layout(image,
+           constraints: new BoxConstraints(
+              minWidth: 5.0,
+              minHeight: 5.0,
+              maxWidth: 16.0,
+              maxHeight: 16.0));
+    expect(image.size.width, equals(8.0));
+    expect(image.size.height, equals(16.0));
+
+    image = new RenderImage(image: new SquareImage());
+    layout(image,
+           constraints: new BoxConstraints(
+              minWidth: 4.0,
+              minHeight: 4.0,
+              maxWidth: 8.0,
+              maxHeight: 8.0));
+    expect(image.size.width, equals(8.0));
+    expect(image.size.height, equals(8.0));
+
+    image = new RenderImage(image: new WideImage());
+    layout(image,
+           constraints: new BoxConstraints(
+              minWidth: 20.0,
+              minHeight: 20.0,
+              maxWidth: 30.0,
+              maxHeight: 30.0));
+    expect(image.size.width, equals(30.0));
+    expect(image.size.height, equals(20.0));
+
+    image = new RenderImage(image: new TallImage());
+    layout(image,
+           constraints: new BoxConstraints(
+              minWidth: 20.0,
+              minHeight: 20.0,
+              maxWidth: 30.0,
+              maxHeight: 30.0));
+    expect(image.size.width, equals(20.0));
+    expect(image.size.height, equals(30.0));
+  });
+
+  test('Null image sizing', () {
+    RenderImage image;
+
+    image = new RenderImage();
+    layout(image,
+           constraints: new BoxConstraints(
+             minWidth: 25.0,
+             minHeight: 25.0,
+             maxWidth: 100.0,
+             maxHeight: 100.0));
+    expect(image.size.width, equals(25.0));
+    expect(image.size.height, equals(25.0));
+
+    image = new RenderImage(width: 50.0);
+    layout(image,
+           constraints: new BoxConstraints(
+             minWidth: 25.0,
+             minHeight: 25.0,
+             maxWidth: 100.0,
+             maxHeight: 100.0));
+    expect(image.size.width, equals(50.0));
+    expect(image.size.height, equals(25.0));
+
+    image = new RenderImage(height: 50.0);
+    layout(image,
+           constraints: new BoxConstraints(
+             minWidth: 25.0,
+             minHeight: 25.0,
+             maxWidth: 100.0,
+             maxHeight: 100.0));
+    expect(image.size.width, equals(25.0));
+    expect(image.size.height, equals(50.0));
+
+    image = new RenderImage(width: 100.0, height: 100.0);
+    layout(image,
+           constraints: new BoxConstraints(
+             minWidth: 25.0,
+             minHeight: 25.0,
+             maxWidth: 75.0,
+             maxHeight: 75.0));
+    expect(image.size.width, equals(75.0));
+    expect(image.size.height, equals(75.0));
+  });
+}

packages/unit/test/rendering/layout_utils.dart

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+import 'package:sky/rendering.dart';
+
+const Size _kTestViewSize = const Size(800.0, 600.0);
+
+class TestRenderView extends RenderView {
+  TestRenderView({ RenderBox child }) : super(child: child) {
+    attach();
+    rootConstraints = new ViewConstraints(size: _kTestViewSize);
+    scheduleInitialLayout();
+  }
+
+  void beginFrame(double timeStamp) {
+    RenderObject.flushLayout();
+  }
+}
+
+RenderView layout(RenderBox box, { BoxConstraints constraints }) {
+  if (constraints != null) {
+    box = new RenderPositionedBox(
+      child: new RenderConstrainedBox(
+        additionalConstraints: constraints,
+        child: box
+      )
+    );
+  }
+
+  TestRenderView renderView = new TestRenderView(child: box);
+  renderView.beginFrame(0.0);
+  return renderView;
+}

packages/unit/test/rendering/stack_test.dart

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+import 'package:sky/rendering.dart';
+import 'package:test/test.dart';
+
+import 'layout_utils.dart';
+
+void main() {
+  test('Stack can layout with top, right, bottom, left 0.0', () {
+    RenderBox size = new RenderConstrainedBox(
+      additionalConstraints: new BoxConstraints.tight(const Size(100.0, 100.0)));
+
+    RenderBox red = new RenderDecoratedBox(
+      decoration: new BoxDecoration(
+        backgroundColor: const Color(0xFFFF0000)
+      ),
+      child: size);
+
+    RenderBox green = new RenderDecoratedBox(
+      decoration: new BoxDecoration(
+        backgroundColor: const Color(0xFFFF0000)
+      ));
+
+    RenderBox stack = new RenderStack(children: [red, green]);
+    (green.parentData as StackParentData)
+      ..top = 0.0
+      ..right = 0.0
+      ..bottom = 0.0
+      ..left = 0.0;
+
+    layout(stack, constraints: const BoxConstraints());
+
+    expect(stack.size.width, equals(100.0));
+    expect(stack.size.height, equals(100.0));
+
+    expect(red.size.width, equals(100.0));
+    expect(red.size.height, equals(100.0));
+
+    expect(green.size.width, equals(100.0));
+    expect(green.size.height, equals(100.0));
+  });
+}

packages/unit/test/rendering/viewport_test.dart

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+import 'package:sky/rendering.dart';
+import 'package:test/test.dart';
+
+import 'layout_utils.dart';
+
+void main() {
+  test('Should be able to hit with negative scroll offset', () {
+    RenderBox size = new RenderConstrainedBox(
+      additionalConstraints: new BoxConstraints.tight(const Size(100.0, 100.0)));
+
+    RenderBox red = new RenderDecoratedBox(
+      decoration: new BoxDecoration(
+        backgroundColor: const Color(0xFFFF0000)
+      ),
+      child: size);
+
+    RenderViewport viewport = new RenderViewport(child: red, scrollOffset: new Offset(0.0, -10.0));
+    RenderView renderView = layout(viewport);
+
+    HitTestResult result;
+
+    result = new HitTestResult();
+    renderView.hitTest(result, position: new Point(15.0, 0.0));
+    expect(result.path.first.target, equals(viewport));
+
+    result = new HitTestResult();
+    renderView.hitTest(result, position: new Point(15.0, 15.0));
+    expect(result.path.first.target, equals(size));
+  });
+}