使用Junit4为mybatis的DAO类写测试用例

mybatis是一款很不错的ORM框架，在项目中得到了很多应用。为了规范单元测试的习惯，特地基于Junit4为DAO层写了测试用例。基础测试从单表开始，数据表基本DDL为：

Create TABLE `user` (
  `id` int(11) NOT NULL AUTO_INCREMENT,
  `userName` varchar(50) DEFAULT NULL,
  `userAge` int(11) DEFAULT NULL,
  `userAddress` varchar(200) DEFAULT NULL,
  PRIMARY KEY (`id`)
) 

 在实际写DAO层单元测试用例时，工程仅需要hamcrest-core,junit-4,mybatis,数据库驱动这四个jar包。创建基础Bean后，书写mybatis启动的核心配置文件config.xml:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE configuration 
PUBLIC "-//mybatis.org//DTD Config 3.0//EN"
"http://mybatis.org/dtd/mybatis-3-config.dtd">
<configuration>
    <typeAliases> 
        <typeAlias alias="User" type="com.model.User"/> 
    </typeAliases> 

    <environments default="development">
        <environment id="development">
        <transactionManager type="JDBC"/>
            <dataSource type="POOLED">
            <property name="driver" value="com.mysql.jdbc.Driver"/>
            <property name="url" value="jdbc:mysql://127.0.0.1:3306/test" />
            <property name="username" value="root"/>
            <property name="password" value="mysql"/>
            </dataSource>
        </environment>
    </environments>
    
    <mappers>
        <mapper resource="com/model/User.xml"/>
    </mappers>
</configuration>

 DAO接口及实现部分代码：

package com.dao;

import com.model.User;

public interface UserDao {
	public User selectUserByID(int id);
	
	public int deleteById(int id);
	
	public int insertOne(User user);
	
	public int updateOne(User user);
}

package com.dao.impl;

import org.apache.ibatis.session.SqlSession;

import com.base.SqlSessionBase;
import com.dao.UserDao;
import com.model.User;

public class UserDaoImpl extends SqlSessionBase implements UserDao{
	private SqlSession session;
	UserDao ud; 
	
	@Override
	public User selectUserByID(int id) {
		try{
			session = SqlSessionBase.getSqlSession();
			ud = session.getMapper(UserDao.class);
			return ud.selectUserByID(id);
		} finally{
			session.close();
		}

	}

	@Override
	public int deleteById(int id) {
		try{
			session = SqlSessionBase.getSqlSession();
			ud = session.getMapper(UserDao.class);
			return ud.deleteById(id);
		} finally{
			session.commit();
			session.close();
		}
	}

	@Override
	public int insertOne(User user) {
		try{
			session = SqlSessionBase.getSqlSession();
			ud = session.getMapper(UserDao.class);
			return ud.insertOne(user);
		} finally{
			session.commit();
			session.close();
		}
	}

	@Override
	public int updateOne(User user) {
		try{
			session = SqlSessionBase.getSqlSession();
			ud = session.getMapper(UserDao.class);
			return ud.updateOne(user);
		} finally{
			session.commit();
			session.close();
		}
	}

}

 工具类：

package com.base;

import java.io.Reader;

import org.apache.ibatis.io.Resources;
import org.apache.ibatis.session.SqlSession;
import org.apache.ibatis.session.SqlSessionFactory;
import org.apache.ibatis.session.SqlSessionFactoryBuilder;

public class SqlSessionBase {
	private static SqlSessionFactory sqlSessionFactory;
	private static Reader reader;
	
	public static SqlSession getSqlSession() {
		try {
			reader = Resources.getResourceAsReader("config.xml");
			sqlSessionFactory = new SqlSessionFactoryBuilder().build(reader);
		} catch (Exception e) {
			e.printStackTrace();
		}
		return sqlSessionFactory.openSession();
	}
	
}

 随后，使用Junit4书写单元测试用例：

package test;

import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.BlockJUnit4ClassRunner;

import com.dao.impl.UserDaoImpl;
import com.model.User;

@RunWith(BlockJUnit4ClassRunner.class)
public class TestUserDao {
	private UserDaoImpl ud = new UserDaoImpl();
	
	@Test
	public void testSelectOne(){
		Assert.assertEquals(ud.selectUserByID(1).getClass(), User.class);
	}
	
	@Test
	public void testDeleteOne(){
		Assert.assertEquals(ud.deleteById(2), 1);
	}
	
	@Test
	public void testInsertone(){
		User user= new User();
		user.setId(2);
		user.setUserAddress("Somewhere");
		Assert.assertEquals(ud.insertOne(user), 1);
	}
	
	@Test
	public void testUpdateOne(){
		User user= new User();
		user.setId(1);
		user.setUserAddress("China xian");
		user.setUserName("New name");
		Assert.assertEquals(ud.updateOne(user), 1);
	}
}

 由于是对DAO层的测试，因此使用的断言较为简洁。Junit4提供的Assert API借用了hamcrest提供的断言语法AsserThat，在字符匹配、集合匹配等方面有了更直观的断言表达。在写单元测试用例中，正确使用断言语法尤为重要。