[英]How to test asynchronous code with Robolectric
I have an activity that presents the user with a list of products inside a HorizontalScrollView
. 我有一个活动,向用户展示HorizontalScrollView
内的产品列表。 I'm using Robolectric to test if the scroll view shows arrows when the list of products is long. 我正在使用Robolectric测试产品列表较长时滚动视图是否显示箭头。
In my Activity I register a OnGlobalLayoutListener
like this: 在我的活动中,我像这样注册一个OnGlobalLayoutListener
:
ViewTreeObserver vto = productsScrollView.getViewTreeObserver();
vto.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
@Override
public void onGlobalLayout() {
productsScrollView.getViewTreeObserver().removeGlobalOnLayoutListener(this);
maxScrollX = productsScrollView.getChildAt(0)
.getMeasuredWidth() - productsScrollView.getMeasuredWidth();
hideShowArrowsAsNeeded();
}
});
This listener is called when the productsScrollView
view hierarchy has changed (ie. I've added some subviews to it). 当productsScrollView
视图层次结构更改时(即,我已经向其中添加了一些子视图),将调用此侦听器。 I run the application and all works perfectly. 我运行该应用程序,并且一切正常。
The problem is that I don't know how to test that the hideShowArrowsAsNeeded
method do its job. 问题是我不知道如何测试hideShowArrowsAsNeeded
方法是否能完成工作。 In my Robolectric test I have this: 在我的Robolectric测试中,我有以下内容:
@Test
public void testThatAHugeNumberOfProductsShowRightArrow() throws Exception {
Product product1 = new Product();
product1.setName("Product1");
Product product2 = new Product();
product2.setName("Product2");
...
ArrayList<Product> productsList = new ArrayList<Product>();
productsList.add(product1);
productsList.add(product2);
...
activity.drawProducts(productsList); // Here I add the views to the scroll view and onGlobalLayout is eventually called, but now right away
assertThat(rightArrow.getVisibility(), equalTo(View.VISIBLE));
}
Of course the test fails because onGlobalLayout
didn't have the chance to run when the assertThat
method is executed. 当然测试会失败,因为在执行assertThat
方法时onGlobalLayout
没有运行的机会。
Any thoughts? 有什么想法吗?
尝试这个:
shadowOf(view.getViewTreeObserver()).fireOnGlobalLayoutListeners();
As of Roboelectric 4.0, ShadowViewTreeObserver is no more. 从Roboelectric 4.0开始,ShadowViewTreeObserver不再可用。
But you should just be able to do something like: 但是您应该只能执行以下操作:
val productScrollView = fragmentController.get().view?.findViewById<View>(R.id.products_scroll_view)
productScrollView?.viewTreeObserver?.dispatchOnGlobalLayout()
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