我正在尝试使用 Espresso。但是我得到了这个错误，如果我遗漏了一些代码，我就没有。

任何想法将不胜感激。

错误日志:

java.lang.NullPointerException: No instrumentation registered. Must run under a registering instrumentation.
    at com.google.android.apps.common.testing.testrunner.util.Checks.checkNotNull(Checks.java:28)
    at com.google.android.apps.common.testing.testrunner.InstrumentationRegistry.getInstance(InstrumentationRegistry.java:23)
    at com.google.android.apps.common.testing.ui.espresso.base.BaseLayerModule.provideTargetContext(BaseLayerModule.java:50)
    at com.google.android.apps.common.testing.ui.espresso.base.BaseLayerModule$$ModuleAdapter$ProvideTargetContextProvidesAdapter.get(BaseLayerModule$$ModuleAdapter.java:101)
    at com.google.android.apps.common.testing.ui.espresso.base.BaseLayerModule$$ModuleAdapter$ProvideTargetContextProvidesAdapter.get(BaseLayerModule$$ModuleAdapter.java:85)
    at com.google.android.apps.common.testing.ui.espresso.base.DefaultFailureHandler$$InjectAdapter.get(DefaultFailureHandler$$InjectAdapter.java:53)
    at com.google.android.apps.common.testing.ui.espresso.base.DefaultFailureHandler$$InjectAdapter.get(DefaultFailureHandler$$InjectAdapter.java:20)
    at com.google.android.apps.common.testing.ui.espresso.base.BaseLayerModule$$ModuleAdapter$ProvideFailureHanderProvidesAdapter.get(BaseLayerModule$$ModuleAdapter.java:555)
    at com.google.android.apps.common.testing.ui.espresso.base.BaseLayerModule$$ModuleAdapter$ProvideFailureHanderProvidesAdapter.get(BaseLayerModule$$ModuleAdapter.java:519)
    at com.google.android.apps.common.testing.ui.espresso.base.BaseLayerModule$FailureHandlerHolder$$InjectAdapter.get(BaseLayerModule$FailureHandlerHolder$$InjectAdapter.java:53)
    at com.google.android.apps.common.testing.ui.espresso.base.BaseLayerModule$FailureHandlerHolder$$InjectAdapter.get(BaseLayerModule$FailureHandlerHolder$$InjectAdapter.java:20)
    at dagger.internal.Linker$SingletonBinding.get(Linker.java:327)
    at com.google.android.apps.common.testing.ui.espresso.base.BaseLayerModule$$ModuleAdapter$ProvideFailureHandlerProvidesAdapter.get(BaseLayerModule$$ModuleAdapter.java:505)
    at com.google.android.apps.common.testing.ui.espresso.base.BaseLayerModule$$ModuleAdapter$ProvideFailureHandlerProvidesAdapter.get(BaseLayerModule$$ModuleAdapter.java:469)
    at com.google.android.apps.common.testing.ui.espresso.ViewInteraction$$InjectAdapter.get(ViewInteraction$$InjectAdapter.java:65)
    at com.google.android.apps.common.testing.ui.espresso.ViewInteraction$$InjectAdapter.get(ViewInteraction$$InjectAdapter.java:20)
    at dagger.ObjectGraph$DaggerObjectGraph.get(ObjectGraph.java:251)
    at com.google.android.apps.common.testing.ui.espresso.Espresso.onView(Espresso.java:58)
    at com.example.espresso.TestExample.testCommand(TestExample.java:28)
    at java.lang.reflect.Method.invokeNative(Native Method)
    at android.test.InstrumentationTestCase.runMethod(InstrumentationTestCase.java:214)
    at android.test.InstrumentationTestCase.runTest(InstrumentationTestCase.java:199)
    at android.test.ActivityInstrumentationTestCase2.runTest(ActivityInstrumentationTestCase2.java:192)
    at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:190)
    at android.test.AndroidTestRunner.runTest(AndroidTestRunner.java:175)
    at android.test.InstrumentationTestRunner.onStart(InstrumentationTestRunner.java:555)
    at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1590)

测试实例.java

public class TestExample extends ActivityInstrumentationTestCase2<ClickActivity>{

    public TestExample() {
        super(ClickActivity.class);
        // TODO Auto-generated constructor stub
    }

    @Override
    protected void setUp() throws Exception {
        // TODO Auto-generated method stub
        super.setUp();
        getActivity();
    }

    public void testCommand(){
        String text = "I Love Espresso!!";
        Espresso.onView(ViewMatchers.withId(R.id.txt)).perform(ViewActions.typeText(text));
        Espresso.onView(ViewMatchers.withId(R.id.button1)).perform(ViewActions.click());
        Espresso.onView(ViewMatchers.withId(R.id.txt)).check(ViewAssertions.matches(ViewMatchers.withText(text)));
    }

}

list .xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.espresso"
    android:versionCode="1"
    android:versionName="1.0" >

    <uses-sdk
        android:minSdkVersion="9"
        android:targetSdkVersion="17" />

    <instrumentation 
        android:targetPackage="com.example.espresso" 
        android:name="android.test.InstrumentationTestRunner" />


    <application
        android:allowBackup="true"
        android:icon="@drawable/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
    <uses-library android:name="android.test.runner" />
    <activity android:name = "ClickActivity"></activity>
    </application>


</manifest>

最佳答案

您的 instrumentation->android:name 的值应该是“com.google.android.apps.common.testing.testrunner.GoogleInstrumentationTestRunner”而不是“android.test.InstrumentationTestRunner”。

然后一定要在配置你的junit测试时选择它:

如果您需要更多指导，我在我的博客上发布了一个快速设置教程。

关于android - 使用 Espresso 时出现 NullPointer 异常，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/19558575/