How to use JUnit with EJB3 and JPA - unit-testing

Question

I'm trying to test my Session Beans with JUnit, but I can't. I've tried a lot of method, but still get some exceptions.
Here is what I need:
I have a few Stateless Session Beans I need to test. Each has the same #PersistenceContext and uses an EntityManager
With my test cases I need to test their methods. For instance: if I add an user with username X and then I try to add another one with the same username, I want to catch an Exception.
Can someone provide a simple and short generic test example? I've already read many, but I always get an error (I get NullPointerException for the EntityManager when I call a method like: sessionBean.method() (which does, for instance, entityManager.find(...)), or I am not able to initialize the Context, or other PersistenceException).

Answer 1

You might be interested in one of the latest posts of Antonio Goncalves:
WYTIWYR : What You Test Is What You Run
It tells about testing EJB with EntityManager using:
Mockito,
Embedded EJB Container,
Arquillian.

Answer 2

I solved creating a Stateless Session Bean and injecting its Entity Manager to test classes. I post the code in case someone will need it:
#Stateless(name = "TestProxy")
#Remote({TestProxyRemote.class})
public class TestProxy implements TestProxyRemote {
#PersistenceContext(unitName = "mph")
private EntityManager em;
#Override
public void persist(Object o) {
em.persist(o);
}
#Override
public void clear() {
em.clear();
}
#Override
public void merge(Object o) {
em.merge(o);
}
#Override
#SuppressWarnings({ "rawtypes", "unchecked" })
public Object find(Class classe, String key) {
return em.find(classe, key);
}
#Override
#SuppressWarnings({ "rawtypes", "unchecked" })
public Object find(Class classe, long key) {
return em.find(classe, key);
}
#SuppressWarnings("rawtypes")
#Override
public List getEntityList(String query) {
Query q = em.createQuery(query);
return q.getResultList();
}
}
public class MyTest {
#BeforeClass
public static void setUpBeforeClass() throws NamingException {
Properties env = new Properties();
env.setProperty(Context.INITIAL_CONTEXT_FACTORY,"org.jnp.interfaces.NamingContextFactory");
env.setProperty(Context.PROVIDER_URL, "localhost:1099");
env.setProperty("java.naming.factory.url.pkgs","org.jboss.naming:org.jnp.interfaces");
jndiContext = new InitialContext(env);
try {
proxy = (TestProxyRemote) jndiContext.lookup("TestProxy/remote");
} catch (NamingException e) {
e.printStackTrace();
}
}
}
Then I can use proxy.find() to get the entities I need, o proxy.getEntityList() to execute a query to retrieve all the instance of an Entity. Or I can add other methods if I want.

Answer 3

Unitils provides a really cool support for JPA. Unitils can be used with JUnit or TestNG and in case you need a mocking framework, Unitils provides its own mocking module as well as support for EasyMock.
#JpaEntityManagerFactory(persistenceUnit = "testPersistenceUnit")
#DataSet(loadStrategy = RefreshLoadStrategy.class)
public class TimeTrackerTest extends UnitilsTestNG {
#TestedObject
private TimeTrackerBean cut = new TimeTrackerBean();
#InjectInto(target="cut",property="em")
#PersistenceContext
private EntityManager em;
#Test
#DataSet("TimeTrackerTest.testAddTimeSlot.xml")
public void yourTest() {
...
}
}
#JpaEntityManagerFactory - Used to specify your persistence unit. It automatically picks up the persistence.xml from your project classpath.
#DataSet - Just in case you need to load any test data you can use this.
#TestedObject - Marks your Class Under Test
#PersistenceContext - Automatically creates your EntityManager instance from the configurations made in the persistence.xml - PersistenceUnit.
#InjectInto - Injects the em instance into the target (cut)
For more information refer this.
Hope this helps.

Answer 4

I'm using Needle for this. It works well with Mockito and EasyMock if you want to mock other objects.
First I write a persistencte.xml for tests (src/test/resources/META-INF) like this:
<persistence-unit name="rapPersistenceTest" transaction-type="RESOURCE_LOCAL">
<properties>
<property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:h2:~/test"/>
...
</properties>
</persistence-unit>
In my Junit-Testclass I write:
public class DaoNeedleTest {
//here Needle will create persistenceContext for your testclass
public static DatabaseRule databaseRule = new DatabaseRule("rapPersistenceTest");
//here you can get the entityManager to manipulate data directly
private final EntityManager entityManager = databaseRule.getEntityManager();
#Rule
public NeedleRule needleRule = new NeedleRule(databaseRule);
//here you can instantiate your daoService
#ObjectUnderTest
DAOService daoService;
#Test
public void test() {
//if your method needs a transaction here you can get it
entityManager.getTransaction().begin();
daoService.yourMethod();
entityManager.getTransaction().commit();
}
You also need a Needle-configuration File in src/test/resources, where you tell what kind of Mock-provider you are using. E.g. I'm using Mockito:
mock.provider=de.akquinet.jbosscc.needle.mock.MockitoProvider
That's it.