@Test
public void testPersistenceUnitDescriptorLoader() throws IOException {

    // GIVEN
    final PersistenceUnitDescriptorLoader loader = new PersistenceUnitDescriptorLoader();
    // WHEN
    final List<PersistenceUnitDescriptor> descriptors = loader.loadPersistenceUnitDescriptors(Collections.emptyMap());
    // THEN
    assertThat(descriptors, notNullValue());
    assertThat(descriptors.size(), equalTo(4));
    assertThat(descriptors, not(hasItem(nullValue())));
}