java 50 lines · 8 steps

Testing a JPA repository against real Postgres in Spring

A @DataJpaTest slice runs repository queries against a throwaway Postgres container instead of an in-memory database.

Explained by highlit

Spring Intermediate integration-testing testcontainers jpa test-slices database

1@DataJpaTest
2@Testcontainers
3@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
4class OrderRepositoryIT {
5 
  @Container
  static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:16-alpine")
          .withDatabaseName("shop")
          .withUsername("shop")
          .withPassword("secret");
11 
  @DynamicPropertySource
  static void datasourceProps(DynamicPropertyRegistry registry) {
      registry.add("spring.datasource.url", postgres::getJdbcUrl);
      registry.add("spring.datasource.username", postgres::getUsername);
      registry.add("spring.datasource.password", postgres::getPassword);
      registry.add("spring.jpa.hibernate.ddl-auto", () -> "create-drop");
  }
19 
  @Autowired
  private TestEntityManager em;
22 
  @Autowired
  private OrderRepository orders;
25 
  private Customer alice;
27 
  @BeforeEach
  void seed() {
      alice = em.persist(new Customer("alice@example.com", "Alice"));
      Customer bob = em.persist(new Customer("bob@example.com", "Bob"));
32 
      em.persist(new Order(alice, new BigDecimal("49.90"), OrderStatus.SHIPPED));
      em.persist(new Order(alice, new BigDecimal("12.00"), OrderStatus.PENDING));
      em.persist(new Order(bob, new BigDecimal("99.99"), OrderStatus.SHIPPED));
36 
      em.flush();
      em.clear();
  }
40 
  @Test
  void findsPendingOrdersForCustomer() {
      List<Order> pending = orders.findByCustomerAndStatus(alice, OrderStatus.PENDING);
44 
      assertThat(pending).hasSize(1)
              .first()
              .extracting(Order::getTotal)
              .isEqualTo(new BigDecimal("12.00"));
  }
50}

01 / 01

STEP 01

Walkthrough

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Three takeaways

1Testing repositories against the real database engine catches dialect-specific bugs an in-memory substitute would hide.
2@DynamicPropertySource wires runtime container details into Spring config before the context starts.
3Flushing and clearing the persistence context forces queries to hit the database rather than the entity cache.

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