Clean up the tests to be more maintainable.

sky/tests/resources/display_list.dart

 
 import 'dart:async';
 import 'dart:sky' as sky;
 import "dart:sky.internals" as internals;
 
 import 'package:sky/widgets/basic.dart';
 import 'package:sky/rendering/box.dart';
 import 'package:sky/rendering/object.dart';
 
 typedef void Logger (String s);
@@ skipping 106 matching lines @@
   }
 }
 
 class TestRenderView extends RenderView {
 
   TestRenderView([ RenderBox child = null ]) : super(child: child) {
     print("TestRenderView enabled");
     attach();
     rootConstraints = new ViewConstraints(width: 800.0, height: 600.0); // arbitrary figures
     scheduleInitialLayout();
-    checkFrame();
+    syncCheckFrame();
   }
 
   int frame = 0;
 
   String lastPaint = '';
   void log(String s) {
     lastPaint += "\n$s";
   }
 
   void paintFrame() {
     RenderObject.debugDoingPaint = true;
     frame += 1;
     lastPaint = '';
     log("PAINT FOR FRAME #${frame} ----------------------------------------------");
     var canvas = new TestDisplayList(rootConstraints.width, rootConstraints.height, log, indent: "${frame} |");
     paint(canvas);
     log("------------------------------------------------------------------------");
     RenderObject.debugDoingPaint = false;
   }
 
   // TEST API:
 
-  void checkFrame() {
+  void syncCheckFrame() {
     RenderObject.flushLayout();
     paintFrame();
     print(lastPaint); // TODO(ianh): figure out how to make this fit the unit testing framework better
   }
 
+  Future checkFrame() {
+    return new Future.microtask(syncCheckFrame);
+  }
+
   void endTest() {
     internals.notifyTestComplete("PAINTED $frame FRAMES");
   }
 
 }
 
 class TestApp extends App {
   TestApp({ this.builder });
 
   Function builder;
 
   Widget build() {
     return builder();
   }
 }
 
 class WidgetTester {
   TestRenderView renderView = new TestRenderView();
 
   Future test(Function builder) {
     runApp(new TestApp(builder: builder), renderViewOverride: renderView);
-    return new Future.microtask(renderView.checkFrame);
+    return renderView.checkFrame();
   }
 
-  Future endTest() {
-    return new Future.microtask(renderView.endTest);
+  void endTest() {
+    renderView.endTest();
   }
 }