是否可以使用 Espresso 的 IdlingResource 等到某个视图

问题描述

在我的测试中，我有一个阶段，在按下按钮后，应用程序会执行大量异步计算并向云服务发出请求，之后它会显示某个视图.

In my test I have a stage where after pressing a button application does a lot of asynchronous calculations and requests to the cloud service, after which it displays a certain view.

是否可以使用 Espresso 的 IdlingResource 实现等到某个视图出现?

Is it possible to use Espresso's IdlingResource implementation to wait until a certain view appears?

我已阅读此处的答案，并且评论似乎表明您可以使用 IdlingResource 代替，但我不明白如何.Espresso 似乎没有任何内置方法来处理长操作，但必须编写自己的等待循环感觉就像是 hack.

I've read an answers here and comments seems to suggest that you can use IdlingResource instead, but I don't understand how. Espresso does not seem to have any built-in way to handle long operations, but having to write your own waiting loops feels like a hack.

有什么方法可以解决这个问题，或者我应该按照链接线程中的答案建议做吗?

Any way to solve this or should I just do as the answer in the linked thread suggests?

推荐答案

您的 IdlingResource 可能如下所示:

Your IdlingResource could look like this:

import android.support.test.espresso.IdlingResource;
import android.support.test.espresso.ViewFinder;
import android.support.test.espresso.ViewInteraction;
import android.view.View;

import org.hamcrest.Matcher;

import java.lang.reflect.Field;

import static android.support.test.espresso.Espresso.onView;

public class ViewShownIdlingResource implements IdlingResource {

    private static final String TAG = ViewShownIdlingResource.class.getSimpleName();

    private final Matcher<View> viewMatcher;
    private ResourceCallback resourceCallback;

    public ViewShownIdlingResource(final Matcher<View> viewMatcher) {
        this.viewMatcher = viewMatcher;
    }

    @Override
    public boolean isIdleNow() {
        View view = getView(viewMatcher);
        boolean idle = view == null || view.isShown();

        if (idle && resourceCallback != null) {
            resourceCallback.onTransitionToIdle();
        }

        return idle;
    }

    @Override
    public void registerIdleTransitionCallback(ResourceCallback resourceCallback) {
        this.resourceCallback = resourceCallback;
    }

    @Override
    public String getName() {
        return this + viewMatcher.toString();
    }

    private static View getView(Matcher<View> viewMatcher) {
        try {
            ViewInteraction viewInteraction = onView(viewMatcher);
            Field finderField = viewInteraction.getClass().getDeclaredField("viewFinder");
            finderField.setAccessible(true);
            ViewFinder finder = (ViewFinder) finderField.get(viewInteraction);
            return finder.getView();
        } catch (Exception e) {
            return null;
        }
    }
}

然后，您可以创建一个等待您的视图的辅助方法:

Then, you could create a helper method waiting for your view:

public void waitViewShown(Matcher<View> matcher) {
    IdlingResource idlingResource = new ViewShownIdlingResource(matcher);///
    try {
        IdlingRegistry.getInstance().register(idlingResource);
        onView(matcher).check(matches(isDisplayed()));  
    } finally {
        IdlingRegistry.getInstance().unregister(idlingResource);
    }    
}

最后，在你的测试中:

@Test
public void someTest() {
    waitViewShown(withId(R.id.<some>));

    //do whatever verification needed afterwards    
} 

您可以通过让 IdlingResource 等待任何条件来改进此示例，而不仅仅是等待可见性条件.

You could improve this example by making IdlingResource wait for any condition, not just for the visibility one.

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