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.

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Spring Intermediate integration-testing testcontainers jpa test-slices database
1@DataJpaTest
2@Testcontainers
3@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
4class OrderRepositoryIT {
5 
6 @Container
7 static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:16-alpine")
8 .withDatabaseName("shop")
9 .withUsername("shop")
10 .withPassword("secret");
11 
12 @DynamicPropertySource
13 static void datasourceProps(DynamicPropertyRegistry registry) {
14 registry.add("spring.datasource.url", postgres::getJdbcUrl);
15 registry.add("spring.datasource.username", postgres::getUsername);
16 registry.add("spring.datasource.password", postgres::getPassword);
17 registry.add("spring.jpa.hibernate.ddl-auto", () -> "create-drop");
18 }
19 
20 @Autowired
21 private TestEntityManager em;
22 
23 @Autowired
24 private OrderRepository orders;
25 
26 private Customer alice;
27 
28 @BeforeEach
29 void seed() {
30 alice = em.persist(new Customer("alice@example.com", "Alice"));
31 Customer bob = em.persist(new Customer("bob@example.com", "Bob"));
32 
33 em.persist(new Order(alice, new BigDecimal("49.90"), OrderStatus.SHIPPED));
34 em.persist(new Order(alice, new BigDecimal("12.00"), OrderStatus.PENDING));
35 em.persist(new Order(bob, new BigDecimal("99.99"), OrderStatus.SHIPPED));
36 
37 em.flush();
38 em.clear();
39 }
40 
41 @Test
42 void findsPendingOrdersForCustomer() {
43 List<Order> pending = orders.findByCustomerAndStatus(alice, OrderStatus.PENDING);
44 
45 assertThat(pending).hasSize(1)
46 .first()
47 .extracting(Order::getTotal)
48 .isEqualTo(new BigDecimal("12.00"));
49 }
50}
01 / 01
STEP 01

Walkthrough

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

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