Spring @DataJpaTest throws exception with Unknown entity

Question

I'm trying to create a repository test with the Spring @DataJpaTest annotation. Even with the simple demo project I receive a IllegalArgumentException: Unknown entity . Do I miss something?

I'm using the Baeldung example for testing with Spring. There is a simple @DataJpaTest and I applied it to my code. When running the test I received a IllegalArgumentException: Unknown entity exception, that repository itself can not be found. So I created a demo project with minimal required classes and still got this error.

the entity class:

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class DemoEntity {

  @Id
  @GeneratedValue(strategy = GenerationType.AUTO)
  private Long id;

  private String name;

  // getter and setter
}

the repositiory class:

@Repository
public interface DemoRepository extends JpaRepository<DemoEntity, Long> {

    Optional<DemoEntity> findByName(String name);
}

and the test class:

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

    @Autowired
    private TestEntityManager entityManager;

    @Autowired
    private DemoRepository repository;

    @Test
    public void test() {
        DemoEntity demo = new DemoEntity() {{
            setName("Tim");
        }};

        entityManager.persistAndFlush(demo);

        Optional<DemoEntity> result = repository.findByName("Tim");

        assertThat(result.isPresent()).isTrue();
    }
}

This test results in the exception:

java.lang.IllegalArgumentException: Unknown entity: com.example.demo.repositories.DemoRepositoryTest$1

at org.hibernate.internal.SessionImpl.firePersist(SessionImpl.java:804)
at org.hibernate.internal.SessionImpl.persist(SessionImpl.java:785)
at org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager.persist(TestEntityManager.java:93)
at org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager.persistAndFlush(TestEntityManager.java:131)
at com.example.demo.repositories.DemoRepositoryTest.test(DemoRepositoryTest.java:31)

I'm using Spring Boot Starter 2.1.1 and Java 10.

Answer 1

The problem is due to the way you are creating the instance of DemoEntity :

DemoEntity demo = new DemoEntity() {{
        setName("Tim");
    }};

Don't use the double-brace initialization syntax and it should work fine.

You are creating a subclass of DemoEntity this way. This is what the error message also indicates with the $1 at the end

See https://stackoverflow.com/a/27521360/40064 for more info on why this is a bad idea anyway.