@DataJpaTest does't work with @GenericGenerator

问题

I tried to test my repository with the @DataJpaTest annotation but something strange appears.

When I use a classic @GeneratedValue every thing is OK, my test succeed. But when I use the generator bellow my test failed.

The test createCountry_should_succeed succeed but the others don't because no exceptions on Valitation on constraint are throw.

@GeneratedValue(generator = "UUID")
@GenericGenerator(name = "UUID", strategy = "com.example.demojpa.CustomIdentifierGenerator") 

For exemple here one of the failed assertion :

java.lang.AssertionError: Expected test to throw an instance of org.springframework.dao.DataIntegrityViolationException

at org.junit.Assert.fail(Assert.java:88)
at org.junit.rules.ExpectedException.failDueToMissingException(ExpectedException.java:263)
at org.junit.rules.ExpectedException.access$200(ExpectedException.java:106)
at org.junit.rules.ExpectedException$ExpectedExceptionStatement.evaluate(ExpectedException.java:245)
at org.junit.rules.RunRules.evaluate(RunRules.java:20)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

My Entity class

@NoArgsConstructor
@Data
@Entity()
@Table(name = "mw_ecom_country", uniqueConstraints = {@UniqueConstraint(name = "abbreviation", columnNames = "abbreviation")})
public class Country {

    @Id
    @GeneratedValue
    //@GeneratedValue(generator = "UUID")
    //@GenericGenerator(name = "UUID", strategy = "com.example.demojpa.CustomIdentifierGenerator")
    protected Long id;

    @NotNull
    @NotEmpty
    private String abbreviation;

    @NotNull
    private String name;

    public Country(Long id, String abbreviation, String name) {
        this.id = id;
        this.abbreviation = abbreviation;
        this.name = name;
    }
}

Here is the test

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

    @Autowired
    private CountryRepository countryRepository;

    @Rule
    public ExpectedException exception = ExpectedException.none();

    @Test
    public void createCountry_should_succeed() {
        Country country = countryRepository.save(new Country(null, "FR", "France"));
        assertThat(country.getId(), notNullValue());
    }

    @Test
    public void createCountry_should_failed_duplicate_abbreviation() {
        exception.expect(DataIntegrityViolationException.class);
        countryRepository.save(new Country(null, "FR", "France"));
        countryRepository.save(new Country(null, "FR", "France"));
    }

    @Test
    public void createCountry_should_failed_null_abbreviation() {
        exception.expect(ConstraintViolationException.class);
        countryRepository.save(new Country(null, null, "France"));
    }

    @Test
    public void createCountry_should_failed_empty_abbreviation() {
        exception.expect(ConstraintViolationException.class);
        countryRepository.save(new Country(null, "", "France"));

    }
}

And the Custom IdentifierGenerator

public class CustomIdentifierGenerator implements IdentifierGenerator {

    @Override
    public Serializable generate(SessionImplementor session, Object object) throws HibernateException {
        return new Random().nextLong();
    }
}

Maybe a bug ? https://github.com/spring-projects/spring-boot/issues/14711

回答1:

This is most likely because your entities never get written to the database.

JPA acts as a write-behind cache. If it doesn't have to write changes to the database it delays it as long as possible. When the ID is generated by the database it has to actually perform the insert in order to obtain the id. This triggers the exception. When the ID is generated in the JVM, the insert will only happen during flushing.

But in your test the transaction never gets committed but rolled back instead, therefore you never see the exception.

Use JpaRepository.saveAndFlush or inject the EntityManager into the test and call flush on it at the end of the test.

See also: JPA cache behaviour when invoke count() method on Spring Data JPA Repository

来源：https://stackoverflow.com/questions/52697057/datajpatest-doest-work-with-genericgenerator