JUnit Testing Spring Service and DAO (with In-Memory Database)

This post describes how to implement JUnit tests for a Spring Web Application's Services and DAO. It is built on top of the Spring MVC-Service-DAO-Persistence Architecture Example. This example is available from Github in the Spring-Web-JPA-Testing directory.

Reminder

• Test Fixture - The fixed state used as a baseline for running tests.
• Unit test - These tests verify that pieces of code (components) perform some functionalities as expected. In a Java environment, these are typically implemented at the class level.
• Integration test - Integration testing is any type of test checking that a set of interacting components perform expected functionalities together correctly.

Configuration

We need a JPA Hibernate configuration for in-memory testing:

@Configuration
@EnableTransactionManagement
public class JpaTestConfig {

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactoryBean(){

        LocalContainerEntityManagerFactoryBean lcemfb
            = new LocalContainerEntityManagerFactoryBean();

        lcemfb.setDataSource(this.dataSource());
        lcemfb.setPackagesToScan(new String[] {"com.jverstry"});
        lcemfb.setPersistenceUnitName("MyTestPU");

        HibernateJpaVendorAdapter va = new HibernateJpaVendorAdapter();
        lcemfb.setJpaVendorAdapter(va);

        Properties ps = new Properties();
        ps.put("hibernate.dialect", "org.hibernate.dialect.HSQLDialect");
        ps.put("hibernate.hbm2ddl.auto", "create");
        lcemfb.setJpaProperties(ps);

        lcemfb.afterPropertiesSet();

        return lcemfb;

    }

    @Bean
    public DataSource dataSource(){

        DriverManagerDataSource ds = new DriverManagerDataSource();

        ds.setDriverClassName("org.hsqldb.jdbcDriver");
        ds.setUrl("jdbc:hsqldb:mem:testdb");
        ds.setUsername("sa");
        ds.setPassword("");

        return ds;

    }

    @Bean
    public PlatformTransactionManager transactionManager(){

        JpaTransactionManager tm = new JpaTransactionManager();

        tm.setEntityManagerFactory(
            this.entityManagerFactoryBean().getObject() );

        return tm;

    }

    @Bean
    public PersistenceExceptionTranslationPostProcessor exceptionTranslation(){
        return new PersistenceExceptionTranslationPostProcessor();
    }

}

We need to exclude the production configuration from package scanning (no "com.jverstry" scanning):

@Configuration
@ComponentScan(basePackages = {
    "com.jverstry.Controller",
    "com.jverstry.DAO",
    "com.jverstry.Item",
    "com.jverstry.Service"
})

public class TestConfig {

    @Bean
    public MyService getMyService() {
        return new MyServiceImpl();
    }

}

Spring Testing Tools

• @RunWith - This is a JUnit annotation allowing one to run a test with a different runner than the one provided by JUnit.
• SpringJUnit4ClassRunner - This is a JUnit test runner for Spring applications. Typically, test classes are annoted with @RunWith(SpringJUnit4ClassRunner.class). 
• @ContextConfiguration - This annotation can be used to specify how to load an applicationContext in Spring test class. This can be configured via XML files or Java configuration objects.

Service Testing

The following class tests the createAndRetrieve() method of our injected MyService implementation:

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes={ JpaTestConfig.class, TestConfig.class })
public class MyServiceImplTest {

    @Autowired
    private MyService myService;

    @Test
    public void testCreateAndRetrieve() {

        MilliTimeItem retr = myService.createAndRetrieve();

        assertNotNull(retr);

    }

}

DAO Testing

The following class tests our DAO implementation. Our implementation is injected with an EntityManager created from our test configuration class defined above.

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes={ JpaTestConfig.class, TestConfig.class })
public class MyPersistenceDAOTest {

    @Autowired
    private MyPersistenceDAO myDAO;

    @Test
    public void testCreateMilliTimeItem() {

        // This operation should not throw an Exception
        long id = myDAO.createMilliTimeItem();

    }

    @Test
    public void testGetMilliTimeItem() {

        long id = myDAO.createMilliTimeItem();
        MilliTimeItem retr = myDAO.getMilliTimeItem(id);

        assertNotNull(retr);
        assertEquals(id,retr.getID());

    }

}

Caveat

When starting to write JUnit tests for Spring, one can come across the following error messages:

Java.lang.ClassFormatError:
Absent Code attribute in method that is not native or abstract in class file javax/validation/Validation

The above is often caused by the following maven dependency:

         <dependency>
            <groupId>javax</groupId>
            <artifactId>javaee-api</artifactId>
            <version>6.0</version>
            <type>jar</type>
         </dependency>

It should be replaced with:

           <dependency>
               <groupId>org.apache.geronimo.specs</groupId>
               <artifactId>geronimo-jpa_2.0_spec</artifactId>
               <version>1.1</version>
               <scope>provided</scope>
           </dependency>

Another error message is:

javax.validation.ValidationException: Unable to find a default provider

This is solved by adding the following maven dependency:

        <dependency>
            <groupId>org.hibernate</groupId>
            <artifactId>hibernate-validator</artifactId>
            <version>4.3.0.Final</version>
        </dependency>

For Spring MVC Controller JUnit testing, see here • More Spring related posts here.

Spring MVC-Service-DAO-Persistence Architecture Example

It is considered good practice to use modularity across Spring web applications. It keeps them maintainable and testable. This can be achieved by using controllers, services and data access objects (DAO). Typically, a user request is handled by a controller, which calls a service, which calls a data access object, which calls the persistence layer implementation.

Using services means that application functionalities can be tested without a test framework simulating user calls to controllers. Separating services from the persistence layer implementation via DAO, allows using an in-memory database (for example) by substituting production DAO implementations, by test DAO implementation pointing to an in-memory database.

The code example used in this post is available from Github in the Spring-MVC-Service-DAO-Persistence-Architecture directory. It is a variation of the Spring Web JPA Hibernate In-Memory example.

MVC Controller Calls The Service Implementation

The following controller is injected with an implementation of MyService. It handles /roundtrip user calls by calling its create() and Retrieve(id) methods, which creates and retrieves an instance of a MilliTimeItem object. It contains a unique ID and a timestamp in milliseconds.

@Controller
public class MyController {

    @Autowired
    private MyService myService;

    @RequestMapping(value = "/")
    public String home(Model model) {
        return "index";
    }

    @RequestMapping(value = "/roundtrip")
    public String persistenceStatus(Model model) {

        long id = myService.create();
        MilliTimeItem retr = myService.retrieve(id);
 
        model.addAttribute("RoundTrip", retr);
 
        return "roundtrip";

    }

}

Service Implementation calls Data Access Objects (DAO)

The DAO is injected in the MyService implementation. The createAndRetrieve() calls the DAO createMilliTimeItem() and getMilliTimeItem() methods. It returns the created and retrieved item.

public class MyServiceImpl implements MyService {

    @Autowired
    private MyPersistenceDAO myDAO;

    @Transactional
    long create();
 
    @Transactional
    MilliTimeItem retrieve(long id);

}

Data Access Object Implementation Calls The Persistence Layer

The DAO implementation is injected with the JPA EntityManager:

@Repository
public class MyPersistenceDAOImpl implements MyPersistenceDAO {

    @PersistenceContext
    private EntityManager em;

    @Override
    public long createMilliTimeItem() {
 
        MilliTimeItem mti = new MilliTimeItem();
        mti.setMilliTime(System.currentTimeMillis());

        em.persist(mti);
        long result = mti.getID();
        em.detach(mti);
 
        return result;
 
    }

    @Override
    public MilliTimeItem getMilliTimeItem(long id) {
        return em.find(MilliTimeItem.class, id);
    }

}

Running the Example

After compiling this example with Maven, it can be run with mvn tomcat:run. Then, browse http://localhost:8585/spring-mvc-service-dao-persistence-architecture/.

The generated output is:

Created MilliTimeItem's ID: 1
Created MilliTimeItem's value: 1346691836108

More Spring related posts here.