Testing JPA-based applications - JUnit in Action - page 384

But again, because the testing infrastructure is already in place, it's easy to repro-
duce the problem. All we have to do is add a new testGetUserByIdWithTelephones()
method: 6

@Test
@DataSets(setUpDataSet="/user-with-telephones.xml")
public void testGetUserByIdWithTelephones() throws Exception {
beginTransaction();
long id = ELFunctionMapperImpl.getId(User.class);
User user = dao.getUserById(id);
commitTransaction(true);
assertUserWithTelephones(user);
}
What about the issue itself? The solution is to use the distinct keyword in the query,
as shown here:

jql = "select distinct(user) from User user left join fetch " +
"user.telephones where id = ?";
Notice that having both testGetUserByIdWithTelephone() and testGetUserById-
WithTelephones() methods is redundant and would make the test cases harder to
maintain. Once we add testGetUserByIdWithTelephones() , we can safely remove
testGetUserByIdWithTelephone() and its companion helpers newUserWithTele-
phone() and assertUserWithTelephone() , which would be replaced by newUser-
WithTelephones() and assertUserWithTelephones() , respectively.
Listing 18.21 shows the final version of UserDaoJpaImpl , with all issues fixed.

Listing 18.21 Final (and improved) version of UserDaoJpaImpl

[...]
public class UserDaoJpaImpl implements UserDao {
public void addUser(User user) {

if ( user == null ) {
throw new IllegalArgumentException("user cannot be null");
}
entityManager.persist(user);
}
public User getUserById( long id) {

String jql = "select distinct(user) from User user left join fetch " +
"user.telephones where id = ?";
Query query = entityManager.createQuery(jql);
query.setParameter(1, id);
@SuppressWarnings("unchecked")
List<User> users = query.getResultList();
// sanity check assertion

6

We also need a new assertUserWithTelephones() method on EntitiesHelper and a new user-with-
telephones.xml dataset, but because they're very similar to the existing method and dataset, they aren't
shown here.