In memory database utility

Configuration of your persistence unit

<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" 
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" 
             version="1.0">
  <persistence-unit name="TestDataModel" transaction-type="RESOURCE_LOCAL">
    <provider>org.hibernate.ejb.HibernatePersistence</provider>
    
    <!-- list of all jpa entity classes -->
    <class>de.akquinet.model.MyEntity</class>

    <properties>
      <property name="hibernate.hbm2ddl.auto" value="create-drop" />
      <property name="hibernate.dialect" value="org.hibernate.dialect.HSQLDialect" />
      <property name="hibernate.connection.driver_class" value="org.hsqldb.jdbcDriver" />
      <property name="hibernate.connection.url" value="jdbc:hsqldb:." />

      <property name="hibernate.jdbc.batch_size" value="0" />
      <property name="hibernate.cache.use_second_level_cache" value="true" />
      <property name="hibernate.cache.provider_class" value="org.hibernate.cache.HashtableCacheProvider" />
    </properties>
        

  </persistence-unit>
</persistence>

Configuration of the jdbc url

If you use the in memory database util and you will not use the default configured jdbc url jdbc:hsqldb:., than place a file named needle.properties in the root directory of the classpath.

For example: needle.properties:

jdbc.url=jdbc:hsqldb:mem:memoryDB

Test your code:

Exampel JPA Entity:

@Entity
public class Person {
        
        @Id
        @GeneratedValue(strategy = GenerationType.AUTO)
        private final Long id = null;
        
        @NotNull
        @Column(nullable = false)
        private String firstname;
        
        @NotNull
        @Column(nullable = false)
        private String lastname;
        
        ... some getter and setter methods
        
}

JUnit Test:

public class PersonDBTest  {

    private InMemoryDatabaseUtil databaseUtil;

    @Before
    public void setUp(){
        databaseUtil = new InMemoryDatabaseUtil();
    }

    @Test
    public void testPersist() throws Exception{
        Person person = new Person();
        person.setFirstname("firstname");
        person.setLastname("lastname");
        
        databaseUtil.saveObject(person);

        List<Person> all = databaseUtil.loadAllObjects(Person.class);

        assertEquals(1, all.size());
    }

    @After
    public void tearDown(){
        databaseUtil.deleteAll();
    }
}