import java.sql.SQLException;
import com.mydb.UserTest;
public interface UserDao {

  /**
   * Insert an user in the database.
   *
   * @param user user to be inserted
   * @return if id the inserted user
   */
  long addUser( UserTest user ) throws SQLException;
  UserTest getUserById( long id ) throws SQLException;
}

import static org.junit.Assert.*;

import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.sql.Connection;
import java.sql.DriverManager;

import org.dbunit.dataset.IDataSet;
import org.dbunit.dataset.ReplacementDataSet;
import org.dbunit.dataset.xml.FlatXmlDataSet;
import org.dbunit.ext.hsqldb.HsqldbConnection;
import org.junit.AfterClass;
import org.junit.BeforeClass;

public abstract class AbstractDbUnitTestCase {

  protected static UserDaoJdbcImpl dao = new UserDaoJdbcImpl();
  protected static Connection connection;
  protected static HsqldbConnection dbunitConnection;

  @BeforeClass
  public static void setupDatabase() throws Exception {
    Class.forName("com.mysql.jdbc.Driver");
    connection = DriverManager.getConnection("jdbc:mysql://mydb/mydb","user","password");
    if (connection != null)
        System.out.println("Connected to the database");
    dbunitConnection = new HsqldbConnection(connection,null);
    dao.setConnection(connection);
  }

  @AfterClass
  public static void closeDatabase() throws Exception {
    if ( dbunitConnection != null ) {
      dbunitConnection.close();
      dbunitConnection = null;
    }
  }

  public static IDataSet getDataSet(String name) throws Exception {
    InputStream inputStream = AbstractDbUnitTestCase.class.getResourceAsStream(name);
    assertNotNull("file " + name + " not found in classpath", inputStream );
    Reader reader = new InputStreamReader(inputStream);
    FlatXmlDataSet dataset = new FlatXmlDataSet(reader);
    return dataset;
  }

  public static IDataSet getReplacedDataSet(String name, long id) throws Exception {
    IDataSet originalDataSet = getDataSet(name);
    return getReplacedDataSet(originalDataSet, id);
  }

  public static IDataSet getReplacedDataSet(IDataSet originalDataSet, long id) throws Exception {
    ReplacementDataSet replacementDataSet = new ReplacementDataSet(originalDataSet);
    replacementDataSet.addReplacementObject("[ID]", id);
    replacementDataSet.addReplacementObject("[NULL]", null);
    return replacementDataSet;
  }

}

import static org.junit.Assert.*;
import static com.test.EntitiesHelper.*;


import org.dbunit.Assertion;
import org.dbunit.dataset.IDataSet;
import org.dbunit.operation.DatabaseOperation;
import org.junit.Ignore;
import org.junit.Test;

import com.mydb.UserTest;

public class UserDaoJdbcImplTest extends AbstractDbUnitTestCase {

  @Test
  public void testGetUserById() throws Exception {
    IDataSet setupDataSet = getDataSet("/user.xml");
    DatabaseOperation.CLEAN_INSERT.execute(dbunitConnection, setupDataSet);
    UserProvaTest user = dao.getUserById(1);
    assertNotNull( user);
    assertEquals( "Jeffrey", user.getFirstName() );
    assertEquals( "Lebowsky", user.getLastName() );
    assertEquals( "ElDuderino", user.getUsername() );
  }

  @Test @Ignore("fails if run together with others")
  public void testAddUser() throws Exception {
    UserProvaTest user = newUser();
    long id = dao.addUser(user);
    assertTrue(id>0);
    IDataSet expectedDataSet = getDataSet("/user.xml");
    IDataSet actualDataSet = dbunitConnection.createDataSet();
    Assertion.assertEquals( expectedDataSet, actualDataSet );
  }

  @Test
  public void testAddUseIgnoringId() throws Exception {
    IDataSet setupDataSet = getDataSet("/user.xml");
    DatabaseOperation.DELETE_ALL.execute(dbunitConnection, setupDataSet);
    UserProvaTest user = newUser();
    long id = dao.addUser(user);
    assertTrue(id>0);
    IDataSet expectedDataSet = getDataSet("/user.xml");
    IDataSet actualDataSet = dbunitConnection.createDataSet();
    Assertion.assertEqualsIgnoreCols( expectedDataSet, actualDataSet, "users", new String[] { "id" } );
  }

  @Test
  public void testGetUserByIdReplacingIds() throws Exception {
    long id = 42;
    IDataSet setupDataset = getReplacedDataSet("/user-token.xml", id );
    DatabaseOperation.INSERT.execute(dbunitConnection, setupDataset);
    UserProvaTest user = dao.getUserById(id);
    assertUser(user);
  }

  @Test
  public void testAddUserReplacingIds() throws Exception {
    IDataSet setupDataSet = getDataSet("/user-token.xml");
    DatabaseOperation.DELETE_ALL.execute(dbunitConnection, setupDataSet);
    UserProvaTest user = newUser();
    long id = dao.addUser(user);
    assertTrue(id>0);
    IDataSet expectedDataSet = getReplacedDataSet(setupDataSet, id );
    IDataSet actualDataSet = dbunitConnection.createDataSet();
    Assertion.assertEquals( expectedDataSet, actualDataSet );
  }

}

<?xml version='1.0' encoding='UTF-8'?>
<dataset>
  <UserTest id="1" username="ElDuderino" first_name="Jeffrey" last_name="Lebowsky" />
</dataset>