[FIXED] Why does running this Spring Data JPA Repository test with JUnit 5 cause a ParameterResolutionException?

Issue

I understand that JUnit 5 introduced substantial changes under the hood, however isnt't this supposed to be configured automatically?

build.gradle:

plugins {
    id 'org.springframework.boot' version '2.2.2.RELEASE'
    id 'io.spring.dependency-management' version '1.0.8.RELEASE'
    id 'java'
}
group = 'com.example'
version = '0.0.1-SNAPSHOT'
sourceCompatibility = '1.8'
repositories {
    mavenCentral()
}
dependencies {
    implementation 'org.springframework.boot:spring-boot-starter-data-jpa'
    implementation 'org.springframework.boot:spring-boot-starter-web'
    compile 'org.imgscalr:imgscalr-lib:4.2'
    runtimeOnly 'com.h2database:h2'
    testImplementation('org.springframework.boot:spring-boot-starter-test') {
        exclude group: 'org.junit.vintage', module: 'junit-vintage-engine'
    }
}
test {
    useJUnitPlatform()
}

Repository, located in src/main/java/com/example/repositories:

import org.adventure.entities.Classified;
import org.springframework.data.repository.CrudRepository;
import org.springframework.stereotype.Repository;

@Repository
public interface ClassifiedRepository extends CrudRepository<Classified, Long> {}

Test, located in src/test/java/com/example/repositories:

import org.adventure.entities.Classified;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
import org.springframework.boot.test.autoconfigure.orm.jpa.TestEntityManager;

import java.util.Optional;

import static org.junit.jupiter.api.Assertions.assertTrue;

@DataJpaTest
public class ClassifiedRepositoryTest {

    private TestEntityManager entityManager;
    private ClassifiedRepository classifiedRepository;

    public ClassifiedRepositoryTest(TestEntityManager entityManager, ClassifiedRepository classifiedRepository) {
        this.entityManager = entityManager;
        this.classifiedRepository = classifiedRepository;
    }

    @Test
    public void classifiedCanBeFoundById() {
        // GIVEN
        Classified classified = new Classified("Cheap bike",
                "Worn bike, used on a hobby level. Needs oiling", 300, "EUR");
        entityManager.persist(classified);
        entityManager.flush();

        // WHEN
        Optional<Classified> found = classifiedRepository.findById(classified.getId());

        // THEN
        assertTrue(found.isPresent());
    }
}

Result: Too long to post here, please see here

Solution

There was a long discussion about this problem on github (https://github.com/spring-projects/spring-framework/issues/22286). You have three options:

• Add the annotation @Autowiredon your constructor. By default, Spring does not make dependency injection in a contructor of a test class. You have to mention it.

    @Autowired
    public ClassifiedRepositoryTest(TestEntityManager entityManager, ClassifiedRepository classifiedRepository) {
        this.entityManager = entityManager;
        this.classifiedRepository = classifiedRepository;
    }

• As discussed on github: Add @TestConstructor(autowireMode = TestConstructor.AutowireMode.ALL) at the top of your test class.

    @TestConstructor(autowireMode = TestConstructor.AutowireMode.ALL)
    @DataJpaTest
    public class ClassifiedRepositoryTest { ... }

• Remove your constructor and annotate your fields with @Autowired.

@Autowired
private TestEntityManager entityManager;
@Autowired
private ClassifiedRepository classifiedRepository;

Answered By - RUARO Thibault
Answer Checked By - Timothy Miller (JavaFixing Admin)