integration-testing

# Integration Testing Skill ## Purpose Test component interactions, database operations, and external API integrations using Spring testing framework with TestContainers. ## When to Use - ✅ Testing repository layer with real database - ✅ Testing REST API endpoints (if applicable) - ✅ Testing Spring Security configuration - ✅ Testing external API integrations ## Spring Integration Test Patterns ```java @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(classes = ApplicationContext.class) @Sql(scripts = "/test-data.sql", executionPhase = Sql.ExecutionPhase.BEFORE_TEST_METHOD) @Sql(scripts = "/cleanup.sql", executionPhase = Sql.ExecutionPhase.AFTER_TEST_METHOD) public class PoliticianIntegrationTest { @Autowired private PoliticianRepository repository; @Test void shouldCreatePoliticianViaApi() { // Arrange PoliticianRequest request = new PoliticianRequest("John", "Doe", "S"); // Act ResponseEntity<Politician> response = restTemplate.postForEntity( "/api/politicians", request, Politician.class ); // Assert assertThat(response.getStatusCode()).isEqualTo(HttpStatus.CREATED); assertThat(response.getBody()).isNotNull(); // Verify in database Politician saved = repository.findById(response.getBody().getId()).orElseThrow(); assertThat(saved.getFirstName()).isEqualTo("John"); } } ``` ## TestContainers for PostgreSQL ```java @Testcontainers @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(classes = ApplicationContext.class) public class DatabaseIntegrationTest { @ClassRule public static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:18") .withDatabaseName("cia_test") .withUsername("test") .withPassword("test"); @BeforeClass public static void setupTestDatabase() { System.setProperty("spring.datasource.url", postgres.getJdbcUrl()); System.setProperty("spring.datasource.username", postgres.getUsername()); System.setProperty("spring.datasource.password", postgres.getPassword()); } @Test public void shouldConnectToDatabase() { assertThat(postgres.isRunning()).isTrue(); } } ``` ## Security Integration Tests ```java @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(classes = {ApplicationContext.class, SecurityConfig.class}) @WebAppConfiguration public class SecurityIntegrationTest { @Autowired private WebApplicationContext context; private MockMvc mockMvc; @Before public void setup() { mockMvc = MockMvcBuilders .webAppContextSetup(context) .apply(springSecurity()) .build(); } @Test @WithMockUser(roles = "ADMIN") public void shouldAllowAdminAccess() throws Exception { mockMvc.perform(get("/api/admin/users")) .andExpect(status().isOk()); } @Test public void shouldDenyUnauthenticatedAccess() throws Exception { mockMvc.perform(get("/api/admin/users")) .andExpect(status().isUnauthorized()); } } ``` ## References - Spring Framework Testing: https://docs.spring.io/spring-framework/reference/testing.html - TestContainers: https://www.testcontainers.org/