[Closes #616] Child actors should be updated

src/engine/Actor.ts

@@ -1166,6 +1166,11 @@ module ex {
        for (var trait of this.traits) {
           trait.update(this, engine, delta);
        }
+
+       // Update child actors
+       for (var i = 0; i < this.children.length; i++) {          
+          this.children[i].update(engine, delta);          
+       }
 
        this.eventDispatcher.emit('update', new UpdateEvent(delta));
        this.emit('postupdate', new PostUpdateEvent(engine, delta, this));

src/spec/ActorSpec.ts

@@ -912,6 +912,19 @@ describe('A game actor', () => {
       expect(fixed.pos.x).toBe(0);
       expect(fixed.pos.y).toBe(50);
    });
+
+   it('updates child actors', () => {
+      var parentActor = new ex.Actor();
+      var childActor = new ex.Actor();
+      scene.add(parentActor);
+      parentActor.add(childActor);
+
+      spyOn(childActor, 'update');
+
+      scene.update(engine, 100);
+
+      expect(childActor.update).toHaveBeenCalled();
+   });
 
    it('draws visible child actors', () => {
       var parentActor = new ex.Actor();