异常测试DEMO

package com.lijun;

import static org.junit.Assert.*;
import org.junit.Before;
import org.junit.Test;

public class Junit4ExceptionTest {

	private User user;
	
	@Before
	public void init() {
		user = null;
	}
	
	@Test(expected = NullPointerException.class)
	public void testUser() {
//		assertNotNull(user.getUserName());
		user.getUserName();
	}
	
}

class User {
	
	private String userName;

	public String getUserName() {
		return userName;
	}

	public void setUserName(String userName) {
		this.userName = userName;
	}
}