@Override
	public void setUp() throws Exception {
		//setUp() is run before a test case is started. 
		//This is where the solo object is created.
		super.setUp(); 
		//The variable solo has to be static, since every time after a case's finished, this class TCCreateNote would be re-instantiated
		// which would lead to soto to re-instantiated to be null if it's not set as static
		
		if(solo == null) {		
			NotePadTest.solo = new Solo(getInstrumentation(),getActivity());	
		}
	}

2.问题分析

/**
     * Utility method for launching an activity with a specific Intent.
     * 
     * <p><b>NOTE:</b> The parameter <i>pkg</i> must refer to the package identifier of the
     * package hosting the activity to be launched, which is specified in the AndroidManifest.xml
     * file.  This is not necessarily the same as the java package name.
     *
     * @param pkg The package hosting the activity to be launched.
     * @param activityCls The activity class to launch.
     * @param intent The intent to launch with
     * @return The activity, or null if non launched.
     */
    @SuppressWarnings("unchecked")
    public final <T extends Activity> T launchActivityWithIntent(
            String pkg,
            Class<T> activityCls,
            Intent intent) {
        intent.setClassName(pkg, activityCls.getName());
        intent.addFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
        T activity = (T) getInstrumentation().startActivitySync(intent);
        getInstrumentation().waitForIdleSync();
        return activity;
    }

    /**
     * Synchronously wait for the application to be idle.  Can not be called
     * from the main application thread -- use {@link #start} to execute
     * instrumentation in its own thread.
     */
    public void waitForIdleSync() {
        validateNotAppThread();
        Idler idler = new Idler(null);
        mMessageQueue.addIdleHandler(idler);
        mThread.getHandler().post(new EmptyRunnable());
        idler.waitForIdle();
    }

• 首先确保调用这个方法的来源不是application的主线程
• 然后把当前等待application变成idle的请求放到消息队列中
• 最后等待app在处理完所有事件达到idle状态的时候返回

• 如果目标activity没有起来，那么启动该activity并放在前台
• 如果目标activity已经起来，那么直接放在前台等待被测试
• 如果该该activity所属application在自动不停的接受事件，直接调用getActivity会因为一直等待application变成idle状态而挂起

solo = new Solo(getInstrumentation());

package com.example.android.notepad.tryout;

import com.robotium.solo.Solo;

import android.test.ActivityInstrumentationTestCase2;
import android.widget.TextView;
import android.app.Activity;

@SuppressWarnings("rawtypes")
public class NotePadTest extends ActivityInstrumentationTestCase2{

	private static Solo solo = null;
	public Activity activity;
	
	private static final int NUMBER_TOTAL_CASES = 2;
	private static int run = 0;
	
	private static Class<?> launchActivityClass;
	//对应re-sign.jar生成出来的信息框里的两个值
	private static String mainActiviy = "com.example.android.notepad.NotesList";
	private static String packageName = "com.example.android.notepad";

	static {

		try {

			launchActivityClass = Class.forName(mainActiviy);

		} catch (ClassNotFoundException e) {

			throw new RuntimeException(e);

		}

	}
	
	
	@SuppressWarnings("unchecked")
	public NotePadTest() {
		super(packageName, launchActivityClass);
	}

	
	@Override
	public void setUp() throws Exception {
		//setUp() is run before a test case is started. 
		//This is where the solo object is created.
		super.setUp(); 
		//The variable solo has to be static, since every time after a case's finished, this class TCCreateNote would be re-instantiated
		// which would lead to soto to re-instantiated to be null if it's not set as static
		//TextView title = (TextView)getActivity().findViewById(Ref.id.title);
		
		if(solo == null) {
			
			NotePadTest.solo = new Solo(getInstrumentation());//, getActivity());
			
		}
	}
	
	@Override
	public void tearDown() throws Exception {
		//Check whether it's the last case executed.
		run += countTestCases();
		if(run >= NUMBER_TOTAL_CASES) {
			solo.finishOpenedActivities();
		}
	}

	public void testAddNoteCNTitle() throws Exception {
		//getActivity();
		Thread.sleep(5000);
		solo.clickOnMenuItem("Add note");
		solo.enterText(0, "中文标签笔记");
		solo.clickOnMenuItem("Save");
		solo.clickInList(0);
		solo.clearEditText(0);
		solo.enterText(0, "Text 1");
		solo.clickOnMenuItem("Save");
		solo.assertCurrentActivity("Expected NotesList Activity", "NotesList");
		
		solo.clickLongOnText("中文标签笔记");
		solo.clickOnText("Delete");
		
		
	}
}

@Override
    public MyActivity getActivity() {
        if (mActivity == null) {
            Intent intent = new Intent(getInstrumentation().getTargetContext(), MyActivity.class);
            intent.setFlags(Intent.FLAG_ACTIVITY_NEW_TASK);
            // register activity that need to be monitored.
            monitor = getInstrumentation().addMonitor(MyActivity.class.getName(), null, false);
            getInstrumentation().getTargetContext().startActivity(intent);
            mActivity = (MyActivity) getInstrumentation().waitForMonitor(monitor);
            setActivity(mActivity);
        }
        return mActivity;
    }