由于“java.lang.NullPointerException”，仪器运行失败

我正在尝试通过扩展测试类来为我的应用程序中的活动编写单元测试用例ActivityUnitTestCase。我之前可以成功运行测试用例，但现在我在运行它们时总是遇到异常。尽管我对处理非常熟悉NullPointerExceptions，我无法找出导致此问题的问题。我找不到任何类似的问题，所以我发布了这个问题。

堆栈跟踪显示我的代码中的这一行有一个空对象引用

activity = startActivity(mIntent, null, null);

But the startActivity方法应该获取我正在测试的活动的实例。我不确定为什么它返回 null。

这是堆栈跟踪。

java.lang.NullPointerException: Attempt to write to field 'android.os.IBinder android.app.ActivityThread.mLastIntendedActivityToken' on a null object reference
at android.app.Activity.performCreate(Activity.java:6372)
at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1119)
at android.support.test.runner.MonitoringInstrumentation.callActivityOnCreate(MonitoringInstrumentation.java:346)
at android.test.ActivityUnitTestCase.startActivity(ActivityUnitTestCase.java:158)
at com.abc.test.MainActivityTest.access$100(MainActivityTest.java:16)
at com.abc.test.MainActivityTest$1.run(MainActivityTest.java:34)
at android.app.Instrumentation$SyncRunnable.run(Instrumentation.java:1891)
at android.os.Handler.handleCallback(Handler.java:739)
at android.os.Handler.dispatchMessage(Handler.java:95)
at android.os.Looper.loop(Looper.java:145)
at android.app.ActivityThread.main(ActivityThread.java:6117)
at java.lang.reflect.Method.invoke(Native Method)
at java.lang.reflect.Method.invoke(Method.java:372)
at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1399)
at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1194)

Test running failed: Instrumentation run failed due to 'java.lang.NullPointerException'

这是测试类

public class MainActivityTest extends ActivityUnitTestCase<MainActivity>{

    private Intent mIntent;
    private MainActivity activity;

    public MainActivityTest() {
        super(MainActivity.class);
    }

    @Override
    protected void setUp() throws Exception {
        super.setUp();
        //Create an intent to launch target Activity as it is not automatically started by Android Instrumentation
        mIntent = new Intent(getInstrumentation().getContext(), MainActivity.class);
        //Start the activity under test in isolation, in the main thread to avoid assertion error.
        getInstrumentation().runOnMainSync(new Runnable() {
            @Override
            public void run() {
                activity = startActivity(mIntent, null, null);
            }
        });
    }

    @Override
    protected void tearDown() throws Exception {
        super.tearDown();
    }

    /**
     * Tests the preconditions of this test fixture.
     */
    @SmallTest
    public void testPreconditions() {
        assertNotNull("MainActivity is null", getActivity());
    }

    @MediumTest
    public void testSecondActivityWasLaunchedWithIntent() {
        // Get the intent for the next started activity
        final Intent launchIntent = getStartedActivityIntent();
        //Verify the intent was not null.
        assertNotNull("Intent was null", launchIntent);
        //Verify that LaunchActivity was finished
        assertTrue(isFinishCalled());
    }
}

@prudhvi 不幸的是，我认为我没有灵丹妙药，但我建议尝试遵循这些步骤 https://code.google.com/p/android-test-kit/wiki/EspressoSetupInstructions升级到较新版本的 SDK 中的新测试支持库。抱歉，我无法提供更多帮助！