Tests are passing when every asserts are in one test but fail when split

Question

I have following code:

@RunWith(SpringJUnit4ClassRunner.class)
@SpringApplicationConfiguration(classes = TRConfig.class)
public class ARepositoryTest {

    @Autowired
    ARepository aRepository;

    private A a = new A("value");

    @Before
    public void setup() {
        aRepository.save(a);
    }

    @Test
    public void findByValue1() {
        assertEquals(a, aRepository.findByValue("value"));
    }

    @Test
    public void findByValue2() {
        assertEquals(null, aRepository.findByValue("inv"));
    }
}

I have following error on second test, I don't know if first passes because second is the first one which runs:

org.springframework.orm.jpa.JpaObjectRetrievalFailureException: Unable to find ...model.a.A with id 10; nested exception is javax.persistence.EntityNotFoundException: Unable to find model.a.A with id 10

But when I do it like this, the test passes:

@Test
    public void findByValue() {
         assertEquals(a, aRepository.findByValue("value"));
         assertEquals(null, aRepository.findByValue("inv"));
    }

Why? What I have to do to make it running properly?

Here is my config:

@EnableAutoConfiguration
@EnableJpaRepositories(basePackageClasses = ARepository.class)
@EntityScan(basePackageClasses = A.class)
@Import({ DataSourceAutoConfiguration.class, HibernateJpaAutoConfiguration.class })
public class TRConfig {
}