Unit test with the database

You have EntityManager per thread, but all share the same database. If you run the tests concurrently, what one test does, may affect the other tests.

It is necessary to create the bank in memory with each test.

I'll quote a tutorial . Where it creates a hibernate.cfg.xml

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE hibernate-configuration PUBLIC "-//Hibernate/Hibernate Configuration DTD 3.0//EN"
                                         "http://hibernate.sourceforge.net/hibernate-configuration-3.0.dtd">
<hibernate-configuration>
 <session-factory name="">
  <property name="hibernate.connection.driver_class">org.hsqldb.jdbcDriver</property>
  <property name="hibernate.connection.url">jdbc:hsqldb:mem:testdb;shutdown=false</property>
  <property name="hibernate.connection.username">sa</property><!-- default username -->
  <property name="hibernate.connection.password"/><!-- default password -->
  <property name="hibernate.connection.pool_size">10</property>
  <property name="hibernate.connection.autocommit">true</property>
  <property name="hibernate.cache.provider_class">org.hibernate.cache.HashtableCacheProvider</property>
  <property name="hibernate.hbm2ddl.auto">create-drop</property><!-- creates the tables from the entites automatically -->
  <property name="show_sql">true</property>
  <property name="dialect">org.hibernate.dialect.HSQLDialect</property>
  <mapping class="blog.hibernate.employee.Employee"/>
 </session-factory>
</hibernate-configuration>

And put in% test%:

    @BeforeClass
    public void init() {
        config = new AnnotationConfiguration();
        config.configure(new File("hibernate.cfg.xml"));
            factory = config.buildSessionFactory();
            hibernateSession = factory.openSession();
        }

It's a little old tutorial, but it should be pretty close to what you need to do in this version of Hibernate.

There is a Hibernate property that is named hibernate.hbm2ddl.auto . When it is in create-drop , it will erase everything and recreate from scratch, ideal situation for your tests. What I usually do is have a base class that is in charge of re-creating the database with each test. Note that this happens with each test method, making running your tests slow, but it's a price I think it's fair to pay. A good reference source is Hibernate's own test suite. They use a different output, which is to re-create the database for each class. To do this, they use some JUnit extensions, which may be too much for the normal case.

Here are some examples I use for personal projects, which may be an inspiration:

META-INF / persistence.xml

, with nothing more, except the property that erases and rebuilds the database.

TestWithEntityManager

, base class for tests that require database.

CategoryServiceTest

As already mentioned in other answers, Hibernate is able to create the database structure by setting the hibernate.hbm2ddl.auto property.

However, the use of this feature is impracticable in somewhat more complex scenarios where, for example, there is a DBA in the process. There are many other issues in this regard, as we often need fine-tuning in the database: index creation, DBMS-specific structures, data loads.

Solutions to this have come in this year's JPA 2.1 specification, which allow SQL scripts to run before or after the metadata construct of the database, or only the scripts to run. See some articles about the subject. So it would be possible to define a script to create the necessary database structure at the beginning of each test.

Another approach to creating a "frankenstein" that blends unit testing and integration (I do not want to get into the discussion of what is) is to use a testing framework that allows for some further adjustments, such as TestNG . This has an API very similar to JUnit, but with some extra features:

• Specify dependency between tests or test group (affects order of execution)
• Specify tests that may or may not run in parallel
• Tests parameterized with a Data Provider

(For comparisons between JUnit and TestNG see these links .)

Finally, I made a brief presentation about TestNG because it allows you to create something between a unit test and an integration test through test groupings and dependency between them.