how to unit test method using "Spring Data JPA" Specifications

Question

I was playing with org.springframework.data.jpa.domain.Specifications, it's just a basic search :

 public Optional<List<Article>> rechercheArticle(String code, String libelle) {
    List<Article> result = null;

    if(StringUtils.isNotEmpty(code) && StringUtils.isNotEmpty(libelle)){
        result = articleRepository.findAll(Specifications.where(ArticleSpecifications.egaliteCode(code)).and(ArticleSpecifications.egaliteLibelle(libelle)));
    }else{
        if(StringUtils.isNotEmpty(code)){
            result= articleRepository.findAll(Specifications.where(ArticleSpecifications.egaliteCode(code)));
        }else{
            result = articleRepository.findAll(Specifications.where(ArticleSpecifications.egaliteLibelle(libelle)));
        }
    }

    if(result.isEmpty()){
        return Optional.empty();
    }else{
        return Optional.of(result);
    }
}

And that's actually working fine but I'd like to write unit tests for this method and I can't figure out how to check specifications passed to my articleRepository.findAll()

At the moment my unit test looks like :

@Test
public void rechercheArticle_okTousCriteres() throws FacturationServiceException {
    String code = "code";
    String libelle = "libelle";
    List<Article> articles = new ArrayList<>();
    Article a1 = new Article();
    articles.add(a1);
    Mockito.when(articleRepository.findAll(Mockito.any(Specifications.class))).thenReturn(articles);


    Optional<List<Article>> result = articleManager.rechercheArticle(code, libelle);

    Assert.assertTrue(result.isPresent());
    //ArgumentCaptor<Specifications> argument = ArgumentCaptor.forClass(Specifications.class);
    Mockito.verify(articleRepository).findAll(Specifications.where(ArticleSpecifications.egaliteCode(code)).and(ArticleSpecifications.egaliteLibelle(libelle)));
    //argument.getValue().toPredicate(root, query, builder);


}

Any idea?

Answer 1

I was having almost the same problems as you had, and I changed my class that contains Specifications to be an object instead of just one class with static methods. This way I can easily mock it, use dependency injection to pass it, and test which methods were called (without using PowerMockito to mock static methods).

If you wanna do like I did, I recommend you to test the correctness of specifications with integration tests, and for the rest, just if the right method was called.

For example:

public class CdrSpecs {

public Specification<Cdr> calledBetween(LocalDateTime start, LocalDateTime end) {
    return (root, query, cb) -> cb.between(root.get(Cdr_.callDate), start, end);
}
}

Then you have an integration test for this method, which will test whether the method is right or not:

@RunWith(SpringRunner.class)
@DataJpaTest
@Sql("/cdr-test-data.sql")
public class CdrIntegrationTest {

@Autowired
private CdrRepository cdrRepository;

private CdrSpecs specs = new CdrSpecs();

@Test
public void findByPeriod() throws Exception {
    LocalDateTime today = LocalDateTime.now();
    LocalDateTime firstDayOfMonth = today.with(TemporalAdjusters.firstDayOfMonth());
    LocalDateTime lastDayOfMonth = today.with(TemporalAdjusters.lastDayOfMonth());
    List<Cdr> cdrList = cdrRepository.findAll(specs.calledBetween(firstDayOfMonth, lastDayOfMonth));
    assertThat(cdrList).isNotEmpty().hasSize(2);
}

And now when you wanna unit test other components, you can test like this, for example:

@RunWith(JUnit4.class)
public class CdrSearchServiceTest {

@Mock
private CdrSpecs specs;
@Mock
private CdrRepository repo;

private CdrSearchService searchService;

@Before
public void setUp() throws Exception {
    initMocks(this);
    searchService = new CdrSearchService(repo, specs);
}

@Test
public void testSearch() throws Exception {

    // some code here that interact with searchService

    verify(specs).calledBetween(any(LocalDateTime.class), any(LocalDateTime.class));
   // and you can verify any other method of specs that should have been called
}

And of course, inside the Service you can still use the where and and static methods of Specifications class.

I hope this can help you.