How cool is integration testing with Spring+Hibernate

I am guilty of not writing integration testing (At least for database related transactions) up until now. So in order to eradicate the guilt i read up on how one can achieve this with minimal effort during the weekend. Came up with a small example depicting how to achieve this with ease using Spring and Hibernate. With integration testing, you can test your DAO(Data access object) layer without ever having to deploy the application. For me this is a huge plus since now i can even test my criteria's, named queries and the sort without having to run the application.

There is a property in hibernate that allows you to specify an sql script to run when the Session factory is initialized. With this, i can now populate tables with data that required by my DAO layer. The property is as follows;

 <prop key="hibernate.hbm2ddl.import_files">import.sql</prop>

According to the hibernate documentation, you can have many comma separated sql scripts.One gotcha here is that you cannot create tables using the script. Because the schema needs to be created first in order for the script to run. Even if you issue a create table statement within the script, this is ignored when executing the script as i saw it.

Let me first show you the DAO class i am going to test;

 package com.unittest.session.example1.dao;

import org.springframework.transaction.annotation.Propagation;
import org.springframework.transaction.annotation.Transactional;

import com.unittest.session.example1.domain.Employee;

@Transactional(propagation = Propagation.REQUIRED)
public interface EmployeeDAO {

 public Long createEmployee(Employee emp);
 
 public Employee getEmployeeById(Long id);
}

package com.unittest.session.example1.dao.hibernate;

import org.springframework.orm.hibernate3.support.HibernateDaoSupport;

import com.unittest.session.example1.dao.EmployeeDAO;
import com.unittest.session.example1.domain.Employee;

public class EmployeeHibernateDAOImpl extends HibernateDaoSupport implements
  EmployeeDAO {

 @Override
 public Long createEmployee(Employee emp) {
  getHibernateTemplate().persist(emp);
  return emp.getEmpId();
 }

 public Employee getEmployeeById(Long id) {
  return getHibernateTemplate().get(Employee.class, id);
 }
}

Nothing major, just a simple DAO with two methods where one is to persist and one is to retrieve. For me to test the retrieval method i need to populate the Employee table with some data. This is where the import sql script which was explained before comes into play. The import.sql file is as follows;

 insert into Employee (empId,emp_name) values (1,'Emp test');

This is just a basic script in which i am inserting one record to the employee table. Note again here that the employee table should be created through the hibernate auto create DDL option in order for the sql script to run. More info can be found here. Also the import.sql script in my instance is within the classpath. This is required in order for it to be picked up to be executed when the Session factory is created.

Next up let us see how easy it is to run integration tests with Spring.

 package com.unittest.session.example1.dao.hibernate;

import static org.junit.Assert.*;

import org.junit.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 org.springframework.test.context.transaction.TransactionConfiguration;

import com.unittest.session.example1.dao.EmployeeDAO;
import com.unittest.session.example1.domain.Employee;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(locations="classpath:spring-context.xml")
@TransactionConfiguration(defaultRollback=true,transactionManager="transactionManager")
public class EmployeeHibernateDAOImplTest {

 @Autowired
 private EmployeeDAO employeeDAO;
 
 @Test
 public void testGetEmployeeById() {
  Employee emp = employeeDAO.getEmployeeById(1L);
  
  assertNotNull(emp);
 }
 
 @Test
 public void testCreateEmployee()
 {
  Employee emp = new Employee();
  emp.setName("Emp123");
  Long key = employeeDAO.createEmployee(emp);
  
  assertEquals(2L, key.longValue());
 }

}

A few things to note here is that you need to instruct to run the test within a Spring context. We use the SpringJUnit4ClassRunner for this. Also the transction attribute is set to defaultRollback=true. Note that with MySQL, for this to work, your tables must have the InnoDB engine set as the MyISAM engine does not support transactions.

And finally i present the spring configuration which wires everything up;

 <?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
 xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
 xsi:schemaLocation="  
          http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd  
          http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd  
          http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd  
          http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-2.5.xsd">


 <context:component-scan base-package="com.unittest.session.example1" />
 <context:annotation-config />

 <tx:annotation-driven />

 <bean id="sessionFactory"
  class="org.springframework.orm.hibernate3.annotation.AnnotationSessionFactoryBean">
  <property name="packagesToScan">
   <list>
    <value>com.unittest.session.example1.**.*</value>
   </list>
  </property>
  <property name="hibernateProperties">
   <props>
    <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
    <prop key="hibernate.connection.driver_class">com.mysql.jdbc.Driver</prop>
    <prop key="hibernate.connection.url">jdbc:mysql://localhost:3306/hbmex1</prop>
    <prop key="hibernate.connection.username">root</prop>
    <prop key="hibernate.connection.password">password</prop>
    <prop key="hibernate.show_sql">true</prop>
    <prop key="hibernate.dialect">org.hibernate.dialect.MySQLDialect</prop>
    <!-- -->
    <prop key="hibernate.hbm2ddl.auto">create</prop>
    <prop key="hibernate.hbm2ddl.import_files">import.sql</prop>
   </props>
  </property>
 </bean>

 <bean id="empDAO"
  class="com.unittest.session.example1.dao.hibernate.EmployeeHibernateDAOImpl">
  <property name="sessionFactory" ref="sessionFactory" />
 </bean>

 <bean id="transactionManager"
  class="org.springframework.orm.hibernate3.HibernateTransactionManager">
  <property name="sessionFactory" ref="sessionFactory" />
 </bean>

</beans>

That is about it. Personally i would much rather use a more light weight in-memory database such as hsqldb in order to run my integration tests.

Here is the eclipse project for anyone who would like to run the program and try it out.