Testcontainers: Real Database Integration Tests

// build.gradle:
testImplementation "org.testcontainers:junit-jupiter"
testImplementation "org.testcontainers:postgresql"
// Optionally use Spring Boot Testcontainers support:
testImplementation "org.springframework.boot:spring-boot-testcontainers"

@Testcontainers
@DataJpaTest
@AutoConfigureTestDatabase(replace = AutoConfigureTestDatabase.Replace.NONE)
class UserRepositoryIntegrationTest {
    @Container
    static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:16-alpine")
        .withDatabaseName("testdb")
        .withUsername("test")
        .withPassword("test");
}

@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);
}

@Bean
@ServiceConnection
static PostgreSQLContainer<?> postgresContainer() {
    return new PostgreSQLContainer<>("postgres:16-alpine");
}

abstract class AbstractIntegrationTest {
    @Container
    static final PostgreSQLContainer<?> POSTGRES =
        new PostgreSQLContainer<>("postgres:16-alpine").withReuse(true);
    static { POSTGRES.start(); }
    @DynamicPropertySource
    static void props(DynamicPropertyRegistry r) {
        r.add("spring.datasource.url",      POSTGRES::getJdbcUrl);
        r.add("spring.datasource.username", POSTGRES::getUsername);
        r.add("spring.datasource.password", POSTGRES::getPassword);
    }
}

@Test
void jsonb_search_works() {
    // Insert row with JSONB column, then query
    List<Event> logins = repo.findByType("login");
    assertEquals(1, logins.size());
}

@Container
static DockerComposeContainer<?> compose = new DockerComposeContainer<>(
    new File("src/test/resources/docker-compose.yml"))
    .withExposedService("postgres", 5432)
    .withExposedService("redis", 6379);

@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)
@Testcontainers
class FullIntegrationTest extends AbstractIntegrationTest {
    @LocalServerPort int port;
    @Autowired TestRestTemplate rest;
    @Test
    void end_to_end_user_creation() {
        ResponseEntity<UserDto> r = rest.postForEntity("/api/users", createReq(), UserDto.class);
        assertEquals(HttpStatus.CREATED, r.getStatusCode());
    }
}