刚学习Spring自动装配，做一个测试用例却无法实现实现自动装配，求解

 package com.mo;

public interface CompactDisc {
    void play();
}

 package com.mo;

import org.springframework.stereotype.Component;

@Component
public class SgtPeppers implements CompactDisc{

    @Override
    public void play() {
        // TODO Auto-generated method stub
        System.out.println("hello");
    }

}

 package com.mo;

import org.springframework.context.annotation.ComponentScan;
import org.springframework.context.annotation.Configuration;


@Configuration
@ComponentScan 
public class SpringConfiguration {
}

 package test;

import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

import static org.junit.Assert.*;

import org.junit.Test;

import com.mo.CompactDisc;
import com.mo.SpringConfiguration;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes=SpringConfiguration.class)
public class Testca {
    @Autowired
    private CompactDisc cd;

    @Test
    public void cdShoundNotBeNUll(){

        assertNotNull(cd);
    }
}

http://blog.csdn.net/zy609398738/article/details/7451724