使用Robotium测试时,多个case不能同时运行，运行到第二个case时，会卡死在启动界面。

我的tearDown方法是这样：
protected void tearDown() throws Exception {
try {

this.solo.finishOpenedActivities();
}
catch (Exception e) {
e.printStackTrace();

}

getActivity().finish();
super.tearDown();
}

报错是这样：
2013:12:23 10:22:28.543 java.lang.NullPointerException at android.app.FragmentManagerImpl.execPendingActions(FragmentManager.java:1372) at android.app.FragmentManagerImpl$1.run(FragmentManager.java:426) at android.os.Handler.handleCallback(Handler.java:615) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4895) at java.lang.reflect.Method.invokeNative(Native Method) at java.lang.reflect.Method.invoke(Method.java:511) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:994) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:761) at dalvik.system.NativeStart.main(Native Method)