当使用AndroidJUnitRunner运行ActivityUnitTestCase时，会抛出RuntimeException异常。

Question

我正在尝试将Espresso 2.0的AndoridJUnitRunner与ActivityUnitTestCase集成。然而，当startActivity()尝试初始化mMockParent = new MockParent()时，我的测试会崩溃。

这是我所做的：

使用Intellij 14 CE创建一个新项目，并对build.gradle进行了一些更改。

android{
    defaultConfig {
        applicationId "com.noob.testing"
        minSdkVersion 9
        targetSdkVersion 21
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"

    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_7
        targetCompatibility JavaVersion.VERSION_1_7
    }
}
dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.android.support:appcompat-v7:21.0.+'

    androidTestCompile('org.mockito:mockito-core:1.9.5')
    androidTestCompile('com.google.dexmaker:dexmaker:1.2')
    androidTestCompile('com.google.dexmaker:dexmaker-mockito:1.2')

    androidTestCompile('com.android.support.test.espresso:espresso-core:2.0')
    androidTestCompile('com.android.support.test:testing-support-lib:0.1')
}

编写一个符合JUnit4风格的单元测试。

@RunWith(AndroidJUnit4.class)
public class MainActivityJUnit4Test extends ActivityUnitTestCase<MainActivity> {
    public MainActivityJUnit4Test() {
        super(MainActivity.class);
    }

    MainActivity activity;

    @Before
    public void setup() throws Exception {
        injectInstrumentation(InstrumentationRegistry.getInstrumentation());
        super.setUp();
        ContextThemeWrapper context = new ContextThemeWrapper(getInstrumentation().getTargetContext(), R.style.AppTheme);
        setActivityContext(context);
        activity = startActivity(new Intent(Intent.ACTION_MAIN), null, null);
    }

    @Test
    public void baseCase() {
        TextView tv = (TextView) activity.findViewById(R.id.tv);
        Assert.assertEquals("Hello World", tv.getText());

    }
}

运行测试，获取堆栈跟踪。

junit.framework.AssertionFailedError
at junit.framework.Assert.fail(Assert.java:48)
at junit.framework.Assert.assertTrue(Assert.java:20)
at junit.framework.Assert.assertNotNull(Assert.java:218)
at junit.framework.Assert.assertNotNull(Assert.java:211)
at android.test.ActivityUnitTestCase.startActivity(ActivityUnitTestCase.java:147)
at com.sdchang.testing.MainActivityJUnit4Test.setup(MainActivityJUnit4Test.java:32)
at java.lang.reflect.Method.invokeNative(Native Method)
at java.lang.reflect.Method.invoke(Method.java:525)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:45)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:42)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:27)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:263)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:68)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:47)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:24)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:231)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:60)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:229)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:50)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:222)
at org.junit.runners.ParentRunner.run(ParentRunner.java:300)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at org.junit.runner.JUnitCore.run(JUnitCore.java:136)
at android.support.test.runner.AndroidJUnitRunner.onStart(AndroidJUnitRunner.java:270)
at android.app.Instrumentation$InstrumentationThread.run(Instrumentation.java:1701)

这个堆栈跟踪实际上是重新抛出的。

java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()

当 startActivity() 尝试初始化 mMockParent = new MockParent() 时发生的错误:

            ComponentName cn = new ComponentName(mActivityClass.getPackage().getName(), 
                    mActivityClass.getName());
            intent.setComponent(cn);
            ActivityInfo info = new ActivityInfo();
            CharSequence title = mActivityClass.getName();
            mMockParent = new MockParent();
            String id = null;

我是否还缺少其他东西才能让AndroidJUnitRunner与ActivityUnitTestCase一起使用？非常感谢您的帮助。

- Some Noob Student

Answer 1

在我不断地撞墙、撞窗和各种家具后，我最终成功让我的测试正常运行了！

从问题追踪器的回复中，我了解到不能从 instrumentation 线程创建新的 Handlers。也就是说，必须在 UI 线程中调用 startActivity()。这导致有 3 种解决方案。

1.使用 Instrumentation 的runOnMainSync()方法。

getInstrumentation().runOnMainSync(new Runnable() {
    @Override
    public void run() {
        activity = startActivity(new Intent(Intent.ACTION_MAIN), null, null);
    }
});

2.创建一个扩展ActivityUnitTestCase的自定义基类并重写startActivity方法。

@Override
protected T startActivity(final Intent intent, final Bundle savedInstanceState,
        final Object lastNonConfigurationInstance) {
    return startActivityOnMainThread(intent, savedInstanceState, lastNonConfigurationInstance);
}

private T startActivityOnMainThread(final Intent intent, final Bundle savedInstanceState,
        final Object lastNonConfigurationInstance) {
    final AtomicReference<T> activityRef = new AtomicReference<>();
    final Runnable activityRunnable = new Runnable() {
        @Override
        public void run() {
            activityRef.set(YourBaseActivityUnitTestCase.super.startActivity(
                    intent, savedInstanceState, lastNonConfigurationInstance));
        }
    };

    if (Looper.myLooper() != Looper.getMainLooper()) {
        getInstrumentation().runOnMainSync(activityRunnable);
    } else {
        activityRunnable.run();
    }

    return activityRef.get();
}

3. 如果你在测试方法中调用startActivity()，并且整个测试可以在主线程上运行，则只需在测试方法上注释@UiThreadTest即可。

在我的测试中，我尝试了所有三种解决方案，但只有1和2会起作用。

- Some Noob Student

---

我没有测试过这个，但也许3不起作用是因为@UiThreadTest似乎只适用于扩展InstrumentationTestCase的测试，而不适用于ActivityUnitTestCase？ [Android Dev Reference] (http://developer.android.com/reference/android/test/UiThreadTest.html) - twelve17

顺便说一下，感谢您间接回答了我的一个问题，即为什么我需要在我的ActivityUnitTestCase中使用runOnMainSync，答案是我最终添加了其他测试，这些测试是ActivityInstrumentationTestCase2的子类，并且我安装了Espresso，这需要将我的build.gradle文件中的testInstrumentationRunner从android.test.InstrumentationTestRunner切换到android.support.test.runner.AndroidJUnitRunner，这会改变之前能够直接调用UI相关方法的行为。 - twelve17