Empty @Entity-tables before running test

DatabaseCleanup.java

import javax.persistence.EntityManager;
import javax.persistence.PersistenceContext;
import javax.persistence.Table;

import java.util.List;
import java.util.stream.Collectors;

import org.springframework.beans.factory.InitializingBean;
import org.springframework.context.annotation.Profile;
import org.springframework.stereotype.Service;
import org.springframework.transaction.annotation.Transactional;

/**
 * Inspirert av: <a href="https://medium.com/@dSebastien/cleaning-up-database-tables-after-each-integration-test-method-with-spring-boot-2-and-kotlin-7279abcdd5cc">
 * https://medium.com/@dSebastien/cleaning-up-database-tables-after-each-integration-test-method-with-spring-boot-2-and-kotlin-7279abcdd5cc
 * </a>
 * <p>
 * Gjør manuell opprydding etter hver test, da automatisk rollback ikke er mulig med kombinasjonen @SpringBootTest og SpringBootTest.WebEnvironment.RANDOM_PORT.
 * <blockquote>
 * If your test is @Transactional, it rolls back the transaction at the end of each test method by default.
 * However, as using this arrangement with either RANDOM_PORT or DEFINED_PORT implicitly provides a real servlet environment,
 * the HTTP client and server run in separate threads and, thus, in separate transactions. Any transaction initiated on
 * the server does not roll back in this case.
 * <cite>
 * <a href="https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-testing.html">
 * https://docs.spring.io/spring-boot/docs/current/reference/html/boot-features-testing.html
 * </a>
 * </cite>
 * </blockquote>
 */
@Service
@Profile("test")
public class DatabaseCleanup implements InitializingBean {

    @PersistenceContext
    private EntityManager entityManager;

    private List<String> tableNames;

    @Transactional
    public void execute() {
        entityManager.flush();
        entityManager.createNativeQuery("SET REFERENTIAL_INTEGRITY FALSE").executeUpdate();

        for (final String tableName : tableNames) {
            entityManager.createNativeQuery("TRUNCATE TABLE " + tableName).executeUpdate();
        }

        entityManager.createNativeQuery("SET REFERENTIAL_INTEGRITY TRUE").executeUpdate();
    }

    @Override
    public void afterPropertiesSet() throws Exception {
        tableNames = entityManager.getMetamodel().getEntities().stream()
                .filter(e -> e.getJavaType().getAnnotation(Table.class) != null)
                .map(e -> e.getJavaType().getAnnotation(Table.class).name())
                .collect(Collectors.toList());
    }
}