Android Espresso 测试在物理设备上失败 (PerformException)

Question

嗨，所以我有这个应用程序，它有这个带有 recyclerview 的 RecipeActivity。

当您单击一个列表项时，它会打开另一个活动，并在 Intent 中传递一个额外的内容。

我只想用 Espresso 测试这个简单的功能（我从它开始）。 这是我的代码：

@RunWith(AndroidJUnit4.class)
    public class ShowIngredientsTest {
    @Rule
    public IntentsTestRule<RecipeActivity> testRule =
        new IntentsTestRule<>(RecipeActivity.class);

    @Test
    public void checkIfIntentWorks() {
        onView(withId(R.id.recipes_recyclerview))
            .perform(RecyclerViewActions.actionOnItemAtPosition(0, click()));

        intended(hasExtraWithKey(RECIPE_PARCEL));
    }
}

现在，奇怪的是，当我在 Nexus 5.0 (Android 7.0) 模拟器上运行它时，它通过了（我已经尝试了两次以确定）。

当我在我的 Oneplus 3（使用 Android 7.1.1）（或者甚至在另一个与 Nexus 5.0 具有相同 api 级别的模拟器）上尝试时，它没有。 这是错误信息：

android.support.test.espresso.PerformException: Error performing 'android.support.test.espresso.contrib.RecyclerViewActions$ActionOnItemAtPositionViewAction@3d98130' on view 'with id: com.onval.bakingapp:id/recipes_recyclerview'.
    at android.support.test.espresso.PerformException$Builder.build(PerformException.java:83)
    at android.support.test.espresso.base.DefaultFailureHandler.getUserFriendlyError(DefaultFailureHandler.java:80)
    at android.support.test.espresso.base.DefaultFailureHandler.handle(DefaultFailureHandler.java:56)
    at android.support.test.espresso.ViewInteraction.runSynchronouslyOnUiThread(ViewInteraction.java:184)
    at android.support.test.espresso.ViewInteraction.doPerform(ViewInteraction.java:115)
    at android.support.test.espresso.ViewInteraction.perform(ViewInteraction.java:87)
    at com.onval.bakingapp.ShowIngredientsTest.checkIfIngredientsAreShows(ShowIngredientsTest.java:34)
    at java.lang.reflect.Method.invoke(Native Method)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at android.support.test.internal.statement.UiThreadStatement.evaluate(UiThreadStatement.java:55)
    at android.support.test.rule.ActivityTestRule$ActivityStatement.evaluate(ActivityTestRule.java:270)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runners.Suite.runChild(Suite.java:128)
    at org.junit.runners.Suite.runChild(Suite.java:27)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:115)
    at android.support.test.internal.runner.TestExecutor.execute(TestExecutor.java:59)
    at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:262)
    at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:2110)
    Caused by: java.lang.IllegalStateException: No view holder at position: 0
    at android.support.test.espresso.contrib.RecyclerViewActions$ActionOnItemAtPositionViewAction.perform(RecyclerViewActions.java:290)
    at android.support.test.espresso.ViewInteraction$1.run(ViewInteraction.java:144)
    at java.util.concurrent.Executors$RunnableAdapter.call(Executors.java:428)
    at java.util.concurrent.FutureTask.run(FutureTask.java:237)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6321)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:886)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:776)
    Tests ran to completion.

可能是什么？为什么模拟器可以在位置0执行动作？为什么它说 viewholder 不存在于那个位置，而它显然存在？模拟器没有这个问题！

我唯一的想法是物理设备更快，它会在创建视图之前进行检查......我试图添加一个

.perform(RecyclerViewActions.scrollToPosition(0))

在 onView 和 actionOnItemAtPosition 之间，但它无论如何都不起作用。

我错过了什么？先感谢您！

Answer 1

好的，我解决了，我需要使用 IdlingResources。