JPA tests problem

Question

Hi
I've just started to code a small application using JPA, to be precise I've followed steps from http://schuchert.wikispaces.com/JPA+Tutorial+1+-GettingStarted and I get a strange error:
I made a test class:
package entity;
import javax.persistence.EntityManager;
import javax.persistence.EntityManagerFactory;
import javax.persistence.Persistence;
import org.apache.log4j.BasicConfigurator;
import org.apache.log4j.Level;
import org.apache.log4j.Logger;
import org.junit.After;
import org.junit.Before;
import org.junit.Test;
public class PersonTest {
    private EntityManagerFactory emf;
    private EntityManager em;
    @Before
    public void initEmfAndEm() {
        BasicConfigurator.configure();
        Logger.getLogger("org").setLevel(Level.ERROR);
        emf = Persistence.createEntityManagerFactory("examplePersistenceUnit");
        em = emf.createEntityManager();
    @After
    public void cleanup() {
        em.close();
    @Test
    public void emptyTest() {
}My persistence.xml looks as follows:
<persistence>
    <persistence-unit name="examplePersistenceUnit"
                      transaction-type="RESOURCE_LOCAL">
        <properties>
            <property name="hibernate.show_sql" value="false" />
            <property name="hibernate.format_sql" value="false" />
            <property name="hibernate.connection.driver_class"
                      value="org.hsqldb.jdbcDriver" />
            <property name="hibernate.connection.url"
                      value="jdbc:hsqldb:mem:mem:aname" />
            <property name="hibernate.connection.username" value="sa" />
            <property name="hibernate.dialect"
                      value="org.hibernate.dialect.HSQLDialect" />
            <property name="hibernate.hbm2ddl.auto" value="create" />
        </properties>
    </persistence-unit>
</persistence>While running the test I'm getting null pointer exception on line
em.close().
I've surrounded it with try-catch, and the stack-trace is:
java.lang.NullPointerException
     at entity.PersonTest.cleanup(PersonTest.java:33)
     at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
     at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
     at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
     at java.lang.reflect.Method.invoke(Method.java:597)
     at org.junit.internal.runners.BeforeAndAfterRunner.invokeMethod(BeforeAndAfterRunner.java:74)
     at org.junit.internal.runners.BeforeAndAfterRunner.runAfters(BeforeAndAfterRunner.java:65)
     at org.junit.internal.runners.BeforeAndAfterRunner.runProtected(BeforeAndAfterRunner.java:37)
     at org.junit.internal.runners.TestMethodRunner.runMethod(TestMethodRunner.java:75)
     at org.junit.internal.runners.TestMethodRunner.run(TestMethodRunner.java:45)
     at org.junit.internal.runners.TestClassMethodsRunner.invokeTestMethod(TestClassMethodsRunner.java:66)
     at org.junit.internal.runners.TestClassMethodsRunner.run(TestClassMethodsRunner.java:35)
     at org.junit.internal.runners.TestClassRunner$1.runUnprotected(TestClassRunner.java:42)
     at org.junit.internal.runners.BeforeAndAfterRunner.runProtected(BeforeAndAfterRunner.java:34)
     at org.junit.internal.runners.TestClassRunner.run(TestClassRunner.java:52)
     at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:38)
     at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
     at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460)
     at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673)
     at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386)
     at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196)What did I do wrong?
Greetings
Michal

Answer 1

It seems I used some incompatible jars. I still don't know which ones was it, but I've solved it.