message: Tested set state in unloading triggers render
  Making sure that set state has time to fire before the scene is frozen
diff: @@ -999,4 +999,46 @@ describe('UnloadingHook', function () {
  }
  })
  });
  +
  + describe('Unloading set state', function () {
  + it('should render', function(){
  + var stateNavigator = new StateNavigator([
  + { key: 'sceneA' },
  + { key: 'sceneB', trackCrumbTrail: true }
  + ]);
  + stateNavigator.navigate('sceneA');
  + var {sceneA, sceneB} = stateNavigator.states;
  + var SceneA = () => {
  + var [unloading, setUnloading] = useState(false)
  + useUnloading(() => {
  + setUnloading(true);
  + return true;
  + })
  + return <div id='sceneA' data-unloading={unloading} />;
  + };
  + var SceneB = () => <div />;
  + sceneA.renderScene = () => <SceneA />;
  + sceneB.renderScene = () => <SceneB />;
  + var container = document.createElement('div');
  + act(() => {
  + ReactDOM.render(
  + <NavigationHandler stateNavigator={stateNavigator}>
  + <NavigationMotion>
  + {(_style, scene, key) => <div key={key}>{scene}</div>}
  + </NavigationMotion>
  + </NavigationHandler>,
  + container
  + );
  + });
  + act(() => {
  + stateNavigator.navigate('sceneB');
  + });
  + try {
  + var scene = container.querySelector<HTMLDivElement>("#sceneA");
  + assert.strictEqual(scene.dataset.unloading, 'true');
  + } finally {
  + ReactDOM.unmountComponentAtNode(container);
  + }
  + })
  + });
  });
  