Convert some tests to fn3

packages/flutter/lib/src/fn3/focus.dart

@@ -153,6 +153,7 @@ class FocusState extends State<Focus> {
   }
 
   void initState(BuildContext context) {
+    super.initState(context);
     if (config.autofocus)
       FocusState._moveScopeTo(context, config);
     _updateWidgetRemovalListener(_focusedWidget);

packages/flutter/lib/src/fn3/framework.dart

@@ -631,9 +631,9 @@ abstract class BuildableElement<T extends Widget> extends Element<T> {
   /// binding when scheduleBuild() has been called to mark this element dirty,
   /// and by update() when the Widget has changed.
   void rebuild() {
-    assert(_debugLifecycleState == _ElementLifecycle.mounted);
     if (!_dirty)
       return;
+    assert(_debugLifecycleState == _ElementLifecycle.mounted);
     _dirty = false;
     Widget built;
     try {
@@ -731,7 +731,12 @@ class StatefulComponentElement extends BuildableElement<StatefulComponent> {
     _state._config = widget;
     assert(_state._debugLifecycleState == _StateLifecycle.created);
     _state.initState(this);
-    assert(_state._debugLifecycleState == _StateLifecycle.initialized);
+    assert(() {
+      if (_state._debugLifecycleState == _StateLifecycle.initialized)
+        return true;
+      print('${_state.runtimeType}.initState failed to call super.initState');
+      return false;
+    });
     assert(() { _state._debugLifecycleState = _StateLifecycle.ready; return true; });
     _builder = _state.build;
   }

packages/unit/test/fn3/widget_tester.dart

@@ -6,7 +6,7 @@ import 'package:sky/src/fn3.dart';
 import '../engine/mock_events.dart';
 
 class RootComponent extends StatefulComponent {
-  RootComponentState createState() => new RootComponentState(this);
+  RootComponentState createState() => new RootComponentState();
 }
 
 class RootComponentState extends State<RootComponent> {
@@ -24,13 +24,13 @@ class RootComponentState extends State<RootComponent> {
 
 class WidgetTester {
 
-  void pumpFrame(Widget widget) {
+  void pumpFrame(Widget widget, [ double frameTimeMs = 0.0 ]) {
     runApp(widget);
-    WidgetFlutterBinding.instance.beginFrame(0.0); // TODO(ianh): https://github.com/flutter/engine/issues/1084
+    WidgetFlutterBinding.instance.beginFrame(frameTimeMs); // TODO(ianh): https://github.com/flutter/engine/issues/1084
   }
 
-  void pumpFrameWithoutChange() {
-    WidgetFlutterBinding.instance.beginFrame(0.0); // TODO(ianh): https://github.com/flutter/engine/issues/1084
+  void pumpFrameWithoutChange([ double frameTimeMs = 0.0 ]) {
+    WidgetFlutterBinding.instance.beginFrame(frameTimeMs); // TODO(ianh): https://github.com/flutter/engine/issues/1084
   }
 
 
@@ -64,6 +64,12 @@ class WidgetTester {
     });
   }
 
+  State findStateOfType(Type type) {
+    StatefulComponentElement element = findElement((Element element) {
+      return element is StatefulComponentElement && element.state.runtimeType == type;
+    });
+    return element?.state;
+  }
 
   Point getCenter(Element element) {
     return _getElementPoint(element, (Size size) => size.center(Point.origin));

packages/unit/test/widget/align_test.dart

-import 'package:sky/widgets.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
 
-import 'widget_tester.dart';
+import '../fn3/widget_tester.dart';
 
 void main() {
   test('Align smoke test', () {
     WidgetTester tester = new WidgetTester();
 
-    tester.pumpFrame(() {
-      return new Align(
+    tester.pumpFrame(
+      new Align(
         child: new Container(),
         horizontal: 0.75,
         vertical: 0.75
-      );
-    });
+      )
+    );
 
-    tester.pumpFrame(() {
-      return new Align(
+    tester.pumpFrame(
+      new Align(
         child: new Container(),
         horizontal: 0.5,
         vertical: 0.5
-      );
-    });
+      )
+    );
 
   });
 }

packages/unit/test/widget/block_test.dart

-import 'package:sky/widgets.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
 
 import '../engine/mock_events.dart';
-import 'widget_tester.dart';
+import '../fn3/widget_tester.dart';
 
 final Key blockKey = new Key('test');
 
@@ -10,19 +10,19 @@ void main() {
   test('Cannot scroll a non-overflowing block', () {
     WidgetTester tester = new WidgetTester();
 
-    tester.pumpFrame(() {
-      return new Block([
+    tester.pumpFrame(
+      new Block([
         new Container(
           height: 200.0, // less than 600, the height of the test area
           child: new Text('Hello')
         )
       ],
-      key: blockKey);
-    });
+      key: blockKey)
+    );
     tester.pumpFrameWithoutChange(); // for SizeObservers
 
     Point middleOfContainer = tester.getCenter(tester.findText('Hello'));
-    Point target = tester.getCenter(tester.findWidget((widget) => widget.key == blockKey));
+    Point target = tester.getCenter(tester.findElementByKey(blockKey));
     TestPointer pointer = new TestPointer();
     tester.dispatchEvent(pointer.down(target), target);
     tester.dispatchEvent(pointer.move(target + const Offset(0.0, -10.0)), target);
@@ -37,19 +37,19 @@ void main() {
   test('Can scroll an overflowing block', () {
     WidgetTester tester = new WidgetTester();
 
-    tester.pumpFrame(() {
-      return new Block([
+    tester.pumpFrame(
+      new Block([
         new Container(
           height: 2000.0, // more than 600, the height of the test area
           child: new Text('Hello')
         )
       ],
-      key: blockKey);
-    });
+      key: blockKey)
+    );
     tester.pumpFrameWithoutChange(); // for SizeObservers
 
     Point middleOfContainer = tester.getCenter(tester.findText('Hello'));
-    Point target = tester.getCenter(tester.findWidget((widget) => widget.key == blockKey));
+    Point target = tester.getCenter(tester.findElementByKey(blockKey));
     TestPointer pointer = new TestPointer();
     tester.dispatchEvent(pointer.down(target), target);
     tester.dispatchEvent(pointer.move(target + const Offset(0.0, -10.0)), target);

packages/unit/test/widget/box_decoration_test.dart

 import 'package:sky/material.dart';
-import 'package:sky/widgets.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
 
-import 'widget_tester.dart';
+import '../fn3/widget_tester.dart';
 
 void main() {
   test('Circles can have uniform borders', () {
     WidgetTester tester = new WidgetTester();
 
-    tester.pumpFrame(() {
-      return new Container(
+    tester.pumpFrame(
+      new Container(
         padding: new EdgeDims.all(50.0),
         decoration: new BoxDecoration(
           shape: Shape.circle,
           border: new Border.all(width: 10.0, color: const Color(0x80FF00FF)),
           backgroundColor: Colors.teal[600]
         )
-      );
-    });
+      )
+    );
 
   });
 }

packages/unit/test/widget/center_test.dart

-import 'package:sky/widgets.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
 
-import 'widget_tester.dart';
+import '../fn3/widget_tester.dart';
 
 void main() {
   test('Can be placed in an infinte box', () {
     WidgetTester tester = new WidgetTester();
 
-    tester.pumpFrame(() {
-      return new Block([new Center()]);
-    });
+    tester.pumpFrame(new Block([new Center()]));
   });
 
 }

packages/unit/test/widget/date_picker_test.dart

-import 'package:sky/widgets.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
 
-import 'widget_tester.dart';
+import '../fn3/widget_tester.dart';
 
 void main() {
   test('Can select a day', () {
@@ -9,26 +9,24 @@ void main() {
 
     DateTime currentValue;
 
-    Widget builder() {
-      return new Block([
-        new DatePicker(
-          selectedDate: new DateTime.utc(2015, 6, 9, 7, 12),
-          firstDate: new DateTime.utc(2013),
-          lastDate: new DateTime.utc(2018),
-          onChanged: (DateTime dateTime) {
-            currentValue = dateTime;
-          }
-        )
-      ]);
-    }
+    Widget widget = new Block([
+      new DatePicker(
+        selectedDate: new DateTime.utc(2015, 6, 9, 7, 12),
+        firstDate: new DateTime.utc(2013),
+        lastDate: new DateTime.utc(2018),
+        onChanged: (DateTime dateTime) {
+          currentValue = dateTime;
+        }
+      )
+    ]);
 
-    tester.pumpFrame(builder);
+    tester.pumpFrame(widget);
 
     expect(currentValue, isNull);
     tester.tap(tester.findText('2015'));
-    tester.pumpFrame(builder);
+    tester.pumpFrame(widget);
     tester.tap(tester.findText('2014'));
-    tester.pumpFrame(builder);
+    tester.pumpFrame(widget);
     expect(currentValue, equals(new DateTime(2014, 6, 9)));
     tester.tap(tester.findText('30'));
     expect(currentValue, equals(new DateTime(2013, 1, 30)));

packages/unit/test/widget/duplicate_key_test.dart

-import 'package:sky/src/widgets/framework.dart';
-import 'package:sky/src/widgets/basic.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
-import 'widget_tester.dart';
+
+import '../fn3/widget_tester.dart';
 
 class Item {
   GlobalKey key1 = new GlobalKey();
@@ -12,15 +12,18 @@ List<Item> items = [new Item(), new Item()];
 
 class StatefulLeaf extends StatefulComponent {
   StatefulLeaf({ GlobalKey key }) : super(key: key);
-  void syncConstructorArguments(StatefulLeaf source) { }
+  StatefulLeafState createState() => new StatefulLeafState();
+}
+
+class StatefulLeafState extends State<StatefulLeaf> {
   void test() { setState(() { }); }
-  Widget build() => new Text('leaf');
+  Widget build(BuildContext context) => new Text('leaf');
 }
 
-class KeyedWrapper extends Component {
+class KeyedWrapper extends StatelessComponent {
   KeyedWrapper(this.key1, this.key2);
   Key key1, key2;
-  Widget build() {
+  Widget build(BuildContext context) {
     return new Container(
       key: key1,
       child: new StatefulLeaf(
@@ -40,13 +43,13 @@ Widget builder() {
 void main() {
   test('duplicate key smoke test', () {
     WidgetTester tester = new WidgetTester();
-    tester.pumpFrame(builder);
-    StatefulLeaf leaf = tester.findWidget((widget) => widget is StatefulLeaf);
+    tester.pumpFrame(builder());
+    StatefulLeafState leaf = tester.findStateOfType(StatefulLeafState);
     leaf.test();
     tester.pumpFrameWithoutChange();
     Item lastItem = items[1];
     items.remove(lastItem);
     items.insert(0, lastItem);
-    tester.pumpFrame(builder); // this marks the app dirty and rebuilds it
+    tester.pumpFrame(builder()); // this marks the app dirty and rebuilds it
   });
 }

packages/unit/test/widget/flex_test.dart

-import 'package:sky/widgets.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
 
-import 'widget_tester.dart';
+import '../fn3/widget_tester.dart';
 
 void main() {
   test('Can hit test flex children of stacks', () {
     WidgetTester tester = new WidgetTester();
 
     bool didReceiveTap = false;
-    tester.pumpFrame(() {
-      return new Container(
+    tester.pumpFrame(
+      new Container(
         decoration: const BoxDecoration(
           backgroundColor: const Color(0xFF00FF00)
         ),
@@ -36,8 +36,8 @@ void main() {
             ])
           )
         ])
-      );
-    });
+      )
+    );
 
     tester.tap(tester.findText('X'));
     expect(didReceiveTap, isTrue);

packages/unit/test/widget/gesture_detector_test.dart

-import 'package:sky/widgets.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
 
 import '../engine/mock_events.dart';
-import 'widget_tester.dart';
+import '../fn3/widget_tester.dart';
 
 void main() {
   test('Uncontested scrolls start immediately', () {
@@ -13,22 +13,20 @@ void main() {
     double updatedDragDelta;
     bool didEndDrag = false;
 
-    Widget builder() {
-      return new GestureDetector(
-        onVerticalDragStart: () {
-          didStartDrag = true;
-        },
-        onVerticalDragUpdate: (double scrollDelta) {
-          updatedDragDelta = scrollDelta;
-        },
-        onVerticalDragEnd: (Offset velocity) {
-          didEndDrag = true;
-        },
-        child: new Container()
-      );
-    }
-
-    tester.pumpFrame(builder);
+    Widget widget = new GestureDetector(
+      onVerticalDragStart: () {
+        didStartDrag = true;
+      },
+      onVerticalDragUpdate: (double scrollDelta) {
+        updatedDragDelta = scrollDelta;
+      },
+      onVerticalDragEnd: (Offset velocity) {
+        didEndDrag = true;
+      },
+      child: new Container()
+    );
+
+    tester.pumpFrame(widget);
     expect(didStartDrag, isFalse);
     expect(updatedDragDelta, isNull);
     expect(didEndDrag, isFalse);
@@ -53,7 +51,7 @@ void main() {
     expect(didEndDrag, isTrue);
     didEndDrag = false;
 
-    tester.pumpFrame(() => new Container());
+    tester.pumpFrame(new Container());
   });
 
   test('Match two scroll gestures in succession', () {
@@ -66,16 +64,14 @@ void main() {
     Point downLocation = new Point(10.0, 10.0);
     Point upLocation = new Point(10.0, 20.0);
 
-    Widget builder() {
-      return new GestureDetector(
-        onVerticalDragUpdate: (double delta) { dragDistance += delta; },
-        onVerticalDragEnd: (Offset velocity) { gestureCount += 1; },
-        onHorizontalDragUpdate: (_) { fail("gesture should not match"); },
-        onHorizontalDragEnd: (Offset velocity) { fail("gesture should not match"); },
-        child: new Container()
-      );
-    }
-    tester.pumpFrame(builder);
+    Widget widget = new GestureDetector(
+      onVerticalDragUpdate: (double delta) { dragDistance += delta; },
+      onVerticalDragEnd: (Offset velocity) { gestureCount += 1; },
+      onHorizontalDragUpdate: (_) { fail("gesture should not match"); },
+      onHorizontalDragEnd: (Offset velocity) { fail("gesture should not match"); },
+      child: new Container()
+    );
+    tester.pumpFrame(widget);
 
     tester.dispatchEvent(pointer.down(downLocation), downLocation);
     tester.dispatchEvent(pointer.move(upLocation), downLocation);
@@ -87,5 +83,7 @@ void main() {
 
     expect(gestureCount, 2);
     expect(dragDistance, 20.0);
+
+    tester.pumpFrame(new Container());
   });
 }

packages/unit/test/widget/homogeneous_viewport_test.dart

-import 'package:sky/widgets.dart';
-import 'package:test/test.dart';
-
-import 'widget_tester.dart';
-
-class TestComponent extends StatefulComponent {
-  TestComponent(this.viewport);
-  HomogeneousViewport viewport;
-  void syncConstructorArguments(TestComponent source) {
-    viewport = source.viewport;
-  }
-  bool _flag = true;
-  void go(bool flag) {
-    setState(() {
-      _flag = flag;
-    });
-  }
-  Widget build() {
-    return _flag ? viewport : new Text('Not Today');
-  }
-}
-
-void main() {
-  test('HomogeneousViewport mount/dismount smoke test', () {
-    WidgetTester tester = new WidgetTester();
-
-    List<int> callbackTracker = <int>[];
-
-    // the root view is 800x600 in the test environment
-    // so if our widget is 100 pixels tall, it should fit exactly 6 times.
-
-    TestComponent testComponent;
-    Widget builder() {
-      testComponent = new TestComponent(new HomogeneousViewport(
-        builder: (int start, int count) {
-          List<Widget> result = <Widget>[];
-          for (int index = start; index < start + count; index += 1) {
-            callbackTracker.add(index);
-            result.add(new Container(
-              key: new ValueKey<int>(index),
-              height: 100.0,
-              child: new Text("$index")
-            ));
-          }
-          return result;
-        },
-        startOffset: 0.0,
-        itemExtent: 100.0
-      ));
-      return testComponent;
-    }
-
-    tester.pumpFrame(builder);
-
-    expect(callbackTracker, equals([0, 1, 2, 3, 4, 5]));
-
-    callbackTracker.clear();
-    testComponent.go(false);
-    tester.pumpFrameWithoutChange();
-
-    expect(callbackTracker, equals([]));
-
-    callbackTracker.clear();
-    testComponent.go(true);
-    tester.pumpFrameWithoutChange();
-
-    expect(callbackTracker, equals([0, 1, 2, 3, 4, 5]));
-  });
-
-  test('HomogeneousViewport vertical', () {
-    WidgetTester tester = new WidgetTester();
-
-    List<int> callbackTracker = <int>[];
-
-    // the root view is 800x600 in the test environment
-    // so if our widget is 200 pixels tall, it should fit exactly 3 times.
-    // but if we are offset by 300 pixels, there will be 4, numbered 1-4.
-
-    double offset = 300.0;
-
-    ListBuilder itemBuilder = (int start, int count) {
-      List<Widget> result = <Widget>[];
-      for (int index = start; index < start + count; index += 1) {
-        callbackTracker.add(index);
-        result.add(new Container(
-          key: new ValueKey<int>(index),
-          width: 500.0, // this should be ignored
-          height: 400.0, // should be overridden by itemExtent
-          child: new Text("$index")
-        ));
-      }
-      return result;
-    };
-
-    TestComponent testComponent;
-    Widget builder() {
-      testComponent = new TestComponent(new HomogeneousViewport(
-        builder: itemBuilder,
-        startOffset: offset,
-        itemExtent: 200.0
-      ));
-      return testComponent;
-    }
-
-    tester.pumpFrame(builder);
-
-    expect(callbackTracker, equals([1, 2, 3, 4]));
-
-    callbackTracker.clear();
-
-    offset = 400.0; // now only 3 should fit, numbered 2-4.
-
-    tester.pumpFrame(builder);
-
-    expect(callbackTracker, equals([2, 3, 4]));
-
-    callbackTracker.clear();
-  });
-
-  test('HomogeneousViewport horizontal', () {
-    WidgetTester tester = new WidgetTester();
-
-    List<int> callbackTracker = <int>[];
-
-    // the root view is 800x600 in the test environment
-    // so if our widget is 200 pixels wide, it should fit exactly 4 times.
-    // but if we are offset by 300 pixels, there will be 5, numbered 1-5.
-
-    double offset = 300.0;
-
-    ListBuilder itemBuilder = (int start, int count) {
-      List<Widget> result = <Widget>[];
-      for (int index = start; index < start + count; index += 1) {
-        callbackTracker.add(index);
-        result.add(new Container(
-          key: new ValueKey<int>(index),
-          width: 400.0, // this should be overridden by itemExtent
-          height: 500.0, // this should be ignored
-          child: new Text("$index")
-        ));
-      }
-      return result;
-    };
-
-    TestComponent testComponent;
-    Widget builder() {
-      testComponent = new TestComponent(new HomogeneousViewport(
-        builder: itemBuilder,
-        startOffset: offset,
-        itemExtent: 200.0,
-        direction: ScrollDirection.horizontal
-      ));
-      return testComponent;
-    }
-
-    tester.pumpFrame(builder);
-
-    expect(callbackTracker, equals([1, 2, 3, 4, 5]));
-
-    callbackTracker.clear();
-
-    offset = 400.0; // now only 4 should fit, numbered 2-5.
-
-    tester.pumpFrame(builder);
-
-    expect(callbackTracker, equals([2, 3, 4, 5]));
-
-    callbackTracker.clear();
-  });
-}

packages/unit/test/widget/listener_test.dart

-import 'package:sky/widgets.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
 
-import 'widget_tester.dart';
+import '../fn3/widget_tester.dart';
 
 void main() {
   test('Events bubble up the tree', () {
@@ -9,8 +9,8 @@ void main() {
 
     List<String> log = new List<String>();
 
-    tester.pumpFrame(() {
-      return new Listener(
+    tester.pumpFrame(
+      new Listener(
         onPointerDown: (_) {
           log.add('top');
         },
@@ -28,8 +28,8 @@ void main() {
             )
           )
         )
-      );
-    });
+      )
+    );
 
     tester.tap(tester.findText('X'));
 

packages/unit/test/widget/mixed_viewport_test.dart

-import 'package:sky/widgets.dart';
-import 'package:test/test.dart';
-
-import 'widget_tester.dart';
-
-class TestComponent extends StatefulComponent {
-  TestComponent(this.viewport);
-  MixedViewport viewport;
-  void syncConstructorArguments(TestComponent source) {
-    viewport = source.viewport;
-  }
-  bool _flag = true;
-  void go(bool flag) {
-    setState(() {
-      _flag = flag;
-    });
-  }
-  Widget build() {
-    return _flag ? viewport : new Text('Not Today');
-  }
-}
-
-void main() {
-  test('MixedViewport mount/dismount smoke test', () {
-    WidgetTester tester = new WidgetTester();
-
-    MixedViewportLayoutState layoutState = new MixedViewportLayoutState();
-
-    List<int> callbackTracker = <int>[];
-
-    // the root view is 800x600 in the test environment
-    // so if our widget is 100 pixels tall, it should fit exactly 6 times.
-
-    TestComponent testComponent;
-    Widget builder() {
-      testComponent = new TestComponent(new MixedViewport(
-        builder: (int i) {
-          callbackTracker.add(i);
-          return new Container(
-            key: new ValueKey<int>(i),
-            height: 100.0,
-            child: new Text("$i")
-          );
-        },
-        startOffset: 0.0,
-        layoutState: layoutState
-      ));
-      return testComponent;
-    }
-
-    tester.pumpFrame(builder);
-
-    expect(callbackTracker, equals([0, 1, 2, 3, 4, 5]));
-
-    callbackTracker.clear();
-    testComponent.go(false);
-    tester.pumpFrameWithoutChange();
-
-    expect(callbackTracker, equals([]));
-
-    callbackTracker.clear();
-    testComponent.go(true);
-    tester.pumpFrameWithoutChange();
-
-    expect(callbackTracker, equals([0, 1, 2, 3, 4, 5]));
-
-  });
-
-  test('MixedViewport vertical', () {
-    WidgetTester tester = new WidgetTester();
-
-    MixedViewportLayoutState layoutState = new MixedViewportLayoutState();
-
-    List<int> callbackTracker = <int>[];
-
-    // the root view is 800x600 in the test environment
-    // so if our widget is 200 pixels tall, it should fit exactly 3 times.
-    // but if we are offset by 300 pixels, there will be 4, numbered 1-4.
-
-    double offset = 300.0;
-
-    IndexedBuilder itemBuilder = (int i) {
-      callbackTracker.add(i);
-      return new Container(
-        key: new ValueKey<int>(i),
-        width: 500.0, // this should be ignored
-        height: 200.0,
-        child: new Text("$i")
-      );
-    };
-
-    TestComponent testComponent;
-    Widget builder() {
-      testComponent = new TestComponent(new MixedViewport(
-        builder: itemBuilder,
-        startOffset: offset,
-        layoutState: layoutState
-      ));
-      return testComponent;
-    }
-
-    tester.pumpFrame(builder);
-
-    // 0 is built to find its width
-    expect(callbackTracker, equals([0, 1, 2, 3, 4]));
-
-    callbackTracker.clear();
-
-    offset = 400.0; // now only 3 should fit, numbered 2-4.
-
-    tester.pumpFrame(builder);
-
-    // 0 and 1 aren't built, we know their size and nothing else changed
-    expect(callbackTracker, equals([2, 3, 4]));
-
-    callbackTracker.clear();
-
-  });
-
-  test('MixedViewport horizontal', () {
-    WidgetTester tester = new WidgetTester();
-
-    MixedViewportLayoutState layoutState = new MixedViewportLayoutState();
-
-    List<int> callbackTracker = <int>[];
-
-    // the root view is 800x600 in the test environment
-    // so if our widget is 200 pixels wide, it should fit exactly 4 times.
-    // but if we are offset by 300 pixels, there will be 5, numbered 1-5.
-
-    double offset = 300.0;
-
-    IndexedBuilder itemBuilder = (int i) {
-      callbackTracker.add(i);
-      return new Container(
-        key: new ValueKey<int>(i),
-        height: 500.0, // this should be ignored
-        width: 200.0,
-        child: new Text("$i")
-      );
-    };
-
-    TestComponent testComponent;
-    Widget builder() {
-      testComponent = new TestComponent(new MixedViewport(
-        builder: itemBuilder,
-        startOffset: offset,
-        layoutState: layoutState,
-        direction: ScrollDirection.horizontal
-      ));
-      return testComponent;
-    }
-
-    tester.pumpFrame(builder);
-
-    // 0 is built to find its width
-    expect(callbackTracker, equals([0, 1, 2, 3, 4, 5]));
-
-    callbackTracker.clear();
-
-    offset = 400.0; // now only 4 should fit, numbered 2-5.
-
-    tester.pumpFrame(builder);
-
-    // 0 and 1 aren't built, we know their size and nothing else changed
-    expect(callbackTracker, equals([2, 3, 4, 5]));
-
-    callbackTracker.clear();
-
-  });
-}

packages/unit/test/widget/navigator_test.dart

 import 'package:sky/animation.dart';
-import 'package:sky/widgets.dart';
+import 'package:sky/src/fn3.dart';
 import 'package:test/test.dart';
 
-import 'widget_tester.dart';
+import '../fn3/widget_tester.dart';
 
-class FirstComponent extends Component {
+class FirstComponent extends StatelessComponent {
   FirstComponent(this.navigator);
 
-  final Navigator navigator;
+  final NavigatorState navigator;
 
-  Widget build() {
+  Widget build(BuildContext context) {
     return new GestureDetector(
       onTap: () {
         navigator.pushNamed('/second');
@@ -27,15 +27,15 @@ class FirstComponent extends Component {
 class SecondComponent extends StatefulComponent {
   SecondComponent(this.navigator);
 
-  Navigator navigator;
+  final NavigatorState navigator;
 
-  void syncConstructorArguments(SecondComponent source) {
-    navigator = source.navigator;
-  }
+  SecondComponentState createState() => new SecondComponentState();
+}
 
-  Widget build() {
+class SecondComponentState extends State<SecondComponent> {
+  Widget build(BuildContext context) {
     return new GestureDetector(
-      onTap: navigator.pop,
+      onTap: config.navigator.pop,
       child: new Container(
         decoration: new BoxDecoration(
           backgroundColor: new Color(0xFFFF00FF)
@@ -50,7 +50,7 @@ void main() {
   test('Can navigator navigate to and from a stateful component', () {
     WidgetTester tester = new WidgetTester();
 
-    final NavigationState routes = new NavigationState([
+    final NavigatorHistory routes = new NavigatorHistory([
       new Route(
         name: '/',
         builder: (navigator, route) => new FirstComponent(navigator)
@@ -61,9 +61,7 @@ void main() {
       )
     ]);
 
-    tester.pumpFrame(() {
-      return new Navigator(routes);
-    });
+    tester.pumpFrame(new Navigator(routes));
 
     expect(tester.findText('X'), isNotNull);
     expect(tester.findText('Y'), isNull);