Testcontainers JDBC

Testing JPA repositories with real databases using Testcontainers.

Overview

Testcontainers provides real database instances in Docker containers for integration testing. More reliable than H2 for production parity.

PostgreSQL Setup

Dependencies

<dependency>
  <groupId>org.springframework.boot</groupId>
  <artifactId>spring-boot-testcontainers</artifactId>
  <scope>test</scope>
</dependency>
<dependency>
  <groupId>org.testcontainers</groupId>
  <artifactId>testcontainers-postgresql</artifactId>
  <scope>test</scope>
</dependency>

Basic Test

@DataJpaTest
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
@Testcontainers
class OrderRepositoryPostgresTest {
  
  @Container
  @ServiceConnection
  static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18");
  
  @Autowired
  private OrderRepository orderRepository;
  
  @Autowired
  private TestEntityManager entityManager;
}

MySQL Setup

<dependency>
  <groupId>org.testcontainers</groupId>
  <artifactId>testcontainers-mysql</artifactId>
  <scope>test</scope>
</dependency>

@Container
@ServiceConnection
static MySQLContainer<?> mysql = new MySQLContainer<>("mysql:8.4");

Multiple Databases

@DataJpaTest
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
@Testcontainers
class MultiDatabaseTest {
  
  @Container
  @ServiceConnection(name = "primary")
  static PostgreSQLContainer<?> primaryDb = new PostgreSQLContainer<>("postgres:18");
  
  @Container
  @ServiceConnection(name = "analytics")
  static PostgreSQLContainer<?> analyticsDb = new PostgreSQLContainer<>("postgres:18");
}

Container Reuse (Speed Optimization)

Add to ~/.testcontainers.properties:

testcontainers.reuse.enable=true

Then enable reuse in code:

@Container
@ServiceConnection
static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18")
  .withReuse(true);

Database Initialization

With SQL Scripts

@Container
@ServiceConnection
static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18")
  .withInitScript("schema.sql");

With Flyway

@SpringBootTest
@Testcontainers
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
class MigrationTest {
  
  @Container
  @ServiceConnection
  static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18");
  
  @Autowired
  private Flyway flyway;
  
  @Test
  void shouldApplyMigrations() {
    flyway.migrate();
    // Test code
  }
}

Advanced Configuration

Custom Database/Schema

@Container
@ServiceConnection
static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18")
  .withDatabaseName("testdb")
  .withUsername("testuser")
  .withPassword("testpass")
  .withInitScript("init-schema.sql");

Wait Strategies

@Container
static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18")
  .waitingFor(Wait.forLogMessage(".*database system is ready.*", 1));

Test Example

@DataJpaTest
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
@Testcontainers
class OrderRepositoryTest {
  
  @Container
  @ServiceConnection
  static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18");
  
  @Autowired
  private OrderRepository orderRepository;
  
  @Autowired
  private TestEntityManager entityManager;
  
  @Test
  void shouldFindOrdersByStatus() {
    // Given
    entityManager.persist(new Order("PENDING"));
    entityManager.persist(new Order("COMPLETED"));
    entityManager.flush();
    
    // When
    List<Order> pending = orderRepository.findByStatus("PENDING");
    
    // Then
    assertThat(pending).hasSize(1);
    assertThat(pending.get(0).getStatus()).isEqualTo("PENDING");
  }
  
  @Test
  void shouldSupportPostgresSpecificFeatures() {
    // Can use Postgres-specific features like:
    // - JSONB columns
    // - Array types
    // - Full-text search
  }
}

@DynamicPropertySource Alternative

If not using @ServiceConnection:

@SpringBootTest
@Testcontainers
class OrderServiceTest {
  
  @Container
  static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18");
  
  @DynamicPropertySource
  static void configureProperties(DynamicPropertyRegistry registry) {
    registry.add("spring.datasource.url", postgres::getJdbcUrl);
    registry.add("spring.datasource.username", postgres::getUsername);
    registry.add("spring.datasource.password", postgres::getPassword);
  }
}

Supported Databases

Best Practices

1. Use @ServiceConnection when possible (Spring Boot 3.1+)
2. Enable container reuse for faster local builds
3. Use specific versions (postgres:18) not latest
4. Keep container config in static field
5. Use @DataJpaTest with AutoConfigureTestDatabase.Replace.NONE