How to test Spring Data repositories?

tl;dr

To make it short - there's no way to unit test Spring Data JPA repositories reasonably for a simple reason: it's way to cumbersome to mock all the parts of the JPA API we invoke to bootstrap the repositories. Unit tests don't make too much sense here anyway, as you're usually not writing any implementation code yourself (see the below paragraph on custom implementations) so that integration testing is the most reasonable approach.

Details

We do quite a lot of upfront validation and setup to make sure you can only bootstrap an app that has no invalid derived queries etc.

We create and cache CriteriaQuery instances for derived queries to make sure the query methods do not contain any typos. This requires working with the Criteria API as well as the meta.model.

We verify manually defined queries by asking the EntityManager to create a Query instance for those (which effectively triggers query syntax validation).

We inspect the Metamodel for meta-data about the domain types handled to prepare is-new checks etc.

All stuff that you'd probably defer in a hand-written repository which might cause the application to break at runtime (due to invalid queries etc.).

If you think about it, there's no code you write for your repositories, so there's no need to write any unittests. There's simply no need to as you can rely on our test base to catch basic bugs (if you still happen to run into one, feel free to raise a ticket). However, there's definitely need for integration tests to test two aspects of your persistence layer as they are the aspects that related to your domain:

entity mappings

query semantics (syntax is verified on each bootstrap attempt anyway).

Integration tests

This is usually done by using an in-memory database and test cases that bootstrap a Spring ApplicationContext usually through the test context framework (as you already do), pre-populate the database (by inserting object instances through the EntityManager or repo, or via a plain SQL file) and then execute the query methods to verify the outcome of them.

Testing custom implementations

Custom implementation parts of the repository are written in a way that they don't have to know about Spring Data JPA. They are plain Spring beans that get an EntityManager injected. You might of course wanna try to mock the interactions with it but to be honest, unit-testing the JPA has not been a too pleasant experience for us as well as it works with quite a lot of indirections (EntityManager -> CriteriaBuilder, CriteriaQuery etc.) so that you end up with mocks returning mocks and so on.

---

With Spring Boot + Spring Data it has become quite easy:

@RunWith(SpringRunner.class)
@DataJpaTest
public class MyRepositoryTest {

    @Autowired
    MyRepository subject;

    @Test
    public void myTest() throws Exception {
        subject.save(new MyEntity());
    }
}

The solution by @heez brings up the full context, this only bring up what is needed for JPA+Transaction to work. Note that the solution above will bring up a in memory test database given that one can be found on the classpath.

---

This may come a bit too late, but I have written something for this very purpose. My library will mock out the basic crud repository methods for you as well as interpret most of the functionalities of your query methods. You will have to inject functionalities for your own native queries, but the rest are done for you.

Take a look:

https://github.com/mmnaseri/spring-data-mock

UPDATE

This is now in Maven central and in pretty good shape.

---

If you're using Spring Boot, you can simply use @SpringBootTest to load in your ApplicationContext (which is what your stacktrace is barking at you about). This allows you to autowire in your spring-data repositories. Be sure to add @RunWith(SpringRunner.class) so the spring-specific annotations are picked up:

@RunWith(SpringRunner.class)
@SpringBootTest
public class OrphanManagementTest {

  @Autowired
  private UserRepository userRepository;

  @Test
  public void saveTest() {
    User user = new User("Tom");
    userRepository.save(user);
    Assert.assertNotNull(userRepository.findOne("Tom"));
  }
}

You can read more about testing in spring boot in their docs.

---

When you really want to write an i-test for a spring data repository you can do it like this:

@RunWith(SpringRunner.class)
@DataJpaTest
@EnableJpaRepositories(basePackageClasses = WebBookingRepository.class)
@EntityScan(basePackageClasses = WebBooking.class)
public class WebBookingRepositoryIntegrationTest {

    @Autowired
    private WebBookingRepository repository;

    @Test
    public void testSaveAndFindAll() {
        WebBooking webBooking = new WebBooking();
        webBooking.setUuid("some uuid");
        webBooking.setItems(Arrays.asList(new WebBookingItem()));
        repository.save(webBooking);

        Iterable<WebBooking> findAll = repository.findAll();

        assertThat(findAll).hasSize(1);
        webBooking.setId(1L);
        assertThat(findAll).containsOnly(webBooking);
    }
}

To follow this example you have to use these dependencies:

<dependency>
    <groupId>com.h2database</groupId>
    <artifactId>h2</artifactId>
    <version>1.4.197</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>junit</groupId>
    <artifactId>junit</artifactId>
    <version>4.12</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.assertj</groupId>
    <artifactId>assertj-core</artifactId>
    <version>3.9.1</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

---

In the last version of spring boot 2.1.1.RELEASE, it is simple as :

@RunWith(SpringRunner.class)
@SpringBootTest(classes = SampleApplication.class)
public class CustomerRepositoryIntegrationTest {

    @Autowired
    CustomerRepository repository;

    @Test
    public void myTest() throws Exception {

        Customer customer = new Customer();
        customer.setId(100l);
        customer.setFirstName("John");
        customer.setLastName("Wick");

        repository.save(customer);

        List<?> queryResult = repository.findByLastName("Wick");

        assertFalse(queryResult.isEmpty());
        assertNotNull(queryResult.get(0));
    }
}

Complete code:

https://github.com/jrichardsz/spring-boot-templates/blob/master/003-hql-database-with-integration-test/src/test/java/test/CustomerRepositoryIntegrationTest.java

---

With JUnit5 and @DataJpaTest test will look like (kotlin code):

@DataJpaTest
@ExtendWith(value = [SpringExtension::class])
class ActivityJpaTest {

    @Autowired
    lateinit var entityManager: TestEntityManager

    @Autowired
    lateinit var myEntityRepository: MyEntityRepository

    @Test
    fun shouldSaveEntity() {
        // when
        val savedEntity = myEntityRepository.save(MyEntity(1, "test")

        // then 
        Assertions.assertNotNull(entityManager.find(MyEntity::class.java, savedEntity.id))
    }
}

You could use TestEntityManager from org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager package in order to validate entity state.

---

I solved this by using this way -

    @RunWith(SpringRunner.class)
    @EnableJpaRepositories(basePackages={"com.path.repositories"})
    @EntityScan(basePackages={"com.model"})
    @TestPropertySource("classpath:application.properties")
    @ContextConfiguration(classes = {ApiTestConfig.class,SaveActionsServiceImpl.class})
    public class SaveCriticalProcedureTest {

        @Autowired
        private SaveActionsService saveActionsService;
        .......
        .......
}

---

you can use @DataJpaTest annotation that focuses only on JPA components. By default, it scans for @Entity classes and configures Spring Data JPA repositories annotated with @Repository annotation.

By default, tests annotated with @DataJpaTest are transactional and roll back at the end of each test.

//in Junit 5 @RunWith(SpringRunner.class) annotation is not required

@DataJpaTest
public class EmployeeRepoTest {

@Autowired
EmployeeRepo repository;
 
@Test
public void testRepository() 
{
    EmployeeEntity employee = new EmployeeEntity();
    employee.setFirstName("Anand");
    employee.setProject("Max Account");
     
    repository.save(employee);
     
    Assert.assertNotNull(employee.getId());
  }
}

Junit 4 Syntax will be along with SpringRunner class.

//Junit 4
@RunWith(SpringRunner.class)
@DataJpaTest
public class DataRepositoryTest{
//
}

---

springboot 2.4.5


import javax.persistence.EntityManager;
import javax.persistence.ParameterMode;
import javax.persistence.PersistenceContext;
import javax.persistence.StoredProcedureQuery;

@Repository
public class MyRepositoryImpl implements MyRepository {
    @Autowired
    @PersistenceContext(unitName = "MY_JPA_UNIT")
    private EntityManager entityManager;
    
    
    @Transactional("MY_TRANSACTION_MANAGER")
    @Override
    public MyEntity getSomething(Long id) {
    
        StoredProcedureQuery query = entityManager.createStoredProcedureQuery(
                "MyStoredProcedure", MyEntity.class);
        query.registerStoredProcedureParameter("id", Long.class, ParameterMode.IN);
        query.setParameter("id", id);

        query.execute();
        
        @SuppressWarnings("unchecked")
        MyEntity myEntity = (MyEntity) query.getResultList().stream().findFirst().orElse(null);
        return myEntity;
    }
}

import org.junit.jupiter.api.*;
import org.junit.runner.RunWith;
import org.mockito.InjectMocks;
import org.mockito.Mock;
import org.mockito.Mockito;
import org.mockito.MockitoAnnotations;
import org.mockito.junit.MockitoJUnitRunner;

import javax.persistence.EntityManager;
import javax.persistence.StoredProcedureQuery;
import java.util.List;

import static org.hamcrest.MatcherAssert.assertThat;
import static org.hamcrest.Matchers.*;

@RunWith(MockitoJUnitRunner.Silent.class)
@TestInstance(TestInstance.Lifecycle.PER_CLASS)
public class MyRepositoryTest {

    @InjectMocks
    MyRepositoryImpl myRepository;

    @Mock
    private EntityManager entityManager;

    @Mock
    private StoredProcedureQuery storedProcedureQuery;
    
    @BeforeAll
    public void init() {
        MockitoAnnotations.openMocks(this);
        Mockito.when(entityManager.createStoredProcedureQuery(Mockito.any(), Mockito.any(Class.class)))
                .thenReturn(storedProcedureQuery);
    }

    @AfterAll
    public void tearDown() {
        // something
    }
    
    @Test
    void testMethod() throws Exception {
        Mockito.when(storedProcedureQuery.getResultList()).thenReturn(List.of(myEntityMock));

        MyEntity resultMyEntityList = myRepository.getSomething(1l);

        assertThat(resultMyEntityList,
                allOf(hasProperty("id", org.hamcrest.Matchers.is("1"))
                . . .
        );
    }
}

---

In 2021 with a new initalized springboot 2.5.1 project, I'm doing it like:

...
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.extension.ExtendWith;
import org.mockito.junit.jupiter.MockitoExtension;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;


@ExtendWith(MockitoExtension.class)
@DataJpaTest
public class SomeTest {

    @Autowired
    MyRepository repo;

    @Test
    public void myTest() throws Exception {
        repo.save(new MyRepoEntity());
        /*...
        / Actual Test. For Example: Will my queries work? ... etc.
        / ...
        */
    }
}

---