@Test
  public void testRetrieveDatasetUuidFromIdentifierNs() {
    _repo.deleteAll();

    Metadata metadata1 = newMetadata();
    metadata1 = _repoMetadata.save(metadata1);

    InspireAtomFeed feed1 = newInspireAtomFeed();
    feed1.setMetadataId(metadata1.getId());
    feed1 = _repo.save(feed1);

    String metadataUuid =
        _repo.retrieveDatasetUuidFromIdentifierNs(
            feed1.getAtomDatasetid(), feed1.getAtomDatasetns());
    assertEquals(metadata1.getUuid(), metadataUuid);

    // Test no existing values
    metadataUuid = _repo.retrieveDatasetUuidFromIdentifierNs("aaa", "aaaa");
    assertTrue(StringUtils.isEmpty(metadataUuid));
  }