用 org.junit.Test 测试多线程，遇到 Thread.sleep()就停止而不是睡眠的问题？

如题求问：

测试类如下： public class TestThread {

// @Test

// public void test(){

// MyList myList = new MyList();

// new ThreadA(myList).start();

// new ThreadB(myList).start();

// }

public static void main(String[] args) {
    MyList myList = new MyList();
    new ThreadA(myList).start();
    new ThreadB(myList).start();
}

}

带有 sleep()的类如下： public class ThreadA extends Thread {

protected static Logger logger = LoggerFactory.getLogger(ThreadA.class);
private MyList list;

public ThreadA(MyList myList){
    this.list=myList;
}

@Override
public void run() {
    try {
        for (int i = 0; i <10 ; i++) {
            list.add();
            logger.info("添加了"+(i+1)+"个元素");
            Thread.sleep(1000);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
}

}

用 @Test 启动测试程序，代码走到 sleep()就回停止，而用 main 启动就正常，这是为什么？