Spring Boot Test

@SpringBootTest  // => Loads full ApplicationContext with auto-configuration
// => Equivalent to running SpringApplication.run() in tests
class DonationServiceIntegrationTest {

    @Autowired
    private DonationService donationService;  // => Real service with all dependencies

    @Autowired
    private DonationRepository repository;  // => Real repository with embedded database

    @Test
    void shouldProcessDonation() {
        DonationRequest request = new DonationRequest();
        request.setAmount(BigDecimal.valueOf(1000));
        request.setDonorName("Ahmad");

        DonationResponse response = donationService.processDonation(request);

        assertThat(response.getId()).isNotNull();
        assertThat(repository.findById(response.getId())).isPresent();
    }
}

@SpringBootTest(properties = {
    "spring.datasource.url=jdbc:h2:mem:testdb",  // => Override datasource
    "logging.level.org.hibernate.SQL=DEBUG"  // => Enable SQL logging in tests
})

@SpringBootTest(webEnvironment = WebEnvironment.RANDOM_PORT)
// => Starts embedded server on random port
class DonationControllerIntegrationTest {

    @Autowired
    private TestRestTemplate restTemplate;  // => Auto-configured HTTP client

    @Test
    void shouldCreateDonation() {
        DonationRequest request = new DonationRequest();

        ResponseEntity<DonationResponse> response = restTemplate.postForEntity(
            "/api/donations",
            request,
            DonationResponse.class
        );

        assertThat(response.getStatusCode()).isEqualTo(HttpStatus.CREATED);
    }
}