Repository Tests with Testcontainers

@DataJpaTest starts only JPA components and wraps each test in a rolled-back transaction. Combine it with Testcontainers and @ServiceConnection so Spring Boot automatically points the datasource at a real PostgreSQL container — no URL wiring. Disable the embedded database replacement, and let Flyway apply your real migrations.

@DataJpaTest
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
@Testcontainers
class OrderRepositoryTest {

    @Container
    @ServiceConnection
    static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:17-alpine");

    @Autowired OrderRepository orders;
    @Autowired TestEntityManager em;

    @Test
    void summariesReturnsOnlyRequestedStatuses() {
        var customer = em.persist(new Customer("[email protected]"));
        em.persist(Order.paid(customer, 1_000));
        em.persist(Order.cancelled(customer, 500));

        var page = orders.summaries(customer.getId(), List.of(OrderStatus.PAID), PageRequest.of(0, 10));

        assertThat(page.getContent()).extracting(OrderSummary::status).containsOnly(OrderStatus.PAID);
    }
}

Common pitfalls

• Testing PostgreSQL queries on H2 (dialect differences hide bugs).
• Starting a new container per test class without reuse (slow).
• Relying on data from other tests.

Key points

• @DataJpaTest slice
• Testcontainers + @ServiceConnection
• Real migrations, real engine

Further reading: Spring Boot: Testcontainers