By Boot to Cloud · · 3 min read · 531 views
In Week 6, we implemented professional error handling and logging.
Now, in Week 7, we’ll focus on testing your Spring Boot application — a critical skill for production-ready APIs.
We’ll cover:
Unit testing for isolated logic
Integration testing for controllers, services, and repositories
Performance testing basics
Using JUnit 5, Mockito, and Spring Test
❌ Without tests:
Bugs sneak into production
Refactoring is risky
Deployment confidence is low
✅ With tests:
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You catch errors early
Code is maintainable and refactor-friendly
Continuous integration works reliably
Remember: Tests are documentation + safety net.
In pom.xml:
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-test</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.mockito</groupId>
<artifactId>mockito-core</artifactId>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.testcontainers</groupId>
<artifactId>junit-jupiter</artifactId>
<version>1.19.0</version>
<scope>test</scope>
</dependency>spring-boot-starter-test → JUnit 5, AssertJ, Spring Test utilities
Mockito → Mock dependencies in unit tests
TestContainers → Integration testing with real databases
@ExtendWith(MockitoExtension.class)
public class UserServiceTest {
@Mock
private UserRepository userRepository;
@InjectMocks
private UserService userService;
@Test
void testSaveUser() {
User user = new User();
user.setName("Mahabub");
user.setEmail("mahabub@example.com");
when(userRepository.save(any(User.class))).thenReturn(user);
User saved = userService.saveUser(user);
assertNotNull(saved);
assertEquals("Mahabub", saved.getName());
verify(userRepository, times(1)).save(user);
}
}✅ Key points:
Mock repository to isolate service logic
Verify interactions with verify()
Use assertEquals, assertNotNull, and assertThrows
@SpringBootTest
@AutoConfigureMockMvc
public class UserControllerTest {
@Autowired
private MockMvc mockMvc;
@MockBean
private UserService userService;
@Test
void testGetUserById() throws Exception {
User user = new User();
user.setId(1L);
user.setName("Mahabub");
when(userService.getUserById(1L)).thenReturn(Optional.of(user));
mockMvc.perform(get("/api/users/1"))
.andExpect(status().isOk())
.andExpect(jsonPath("$.name").value("Mahabub"));
}
}✅ Key points:
@SpringBootTest → Loads full Spring context
@AutoConfigureMockMvc → Mock HTTP requests
@MockBean → Replace service with mock
Use TestContainers to spin up a real database during tests:
@Testcontainers
@SpringBootTest
public class UserRepositoryTest {
@Container
public static PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:15")
.withDatabaseName("testdb")
.withUsername("user")
.withPassword("pass");
@Autowired
private UserRepository userRepository;
@Test
void testSaveAndFindUser() {
User user = new User();
user.setName("Mahabub");
user.setEmail("mahabub@example.com");
userRepository.save(user);
Optional<User> found = userRepository.findById(user.getId());
assertTrue(found.isPresent());
assertEquals("Mahabub", found.get().getName());
}
}✅ Benefits:
Tests run against real database
No need for manual setup/teardown
Supports CI/CD pipelines
@Test
void testProtectedEndpoint() throws Exception {
mockMvc.perform(get("/api/admin")
.header("Authorization", "Bearer " + jwtToken))
.andExpect(status().isOk());
}Generate JWT during test or mock authentication
Ensure role-based access works as expected
For simple API performance checks:
Use Spring Boot Actuator / Metrics
Use JMeter / Gatling / k6 for load testing
Example using Actuator metrics:
management:
endpoints:
web:
exposure:
include: health, metrics, httptraceAccess /actuator/metrics/http.server.requests to see request times
Helps identify slow endpoints before production
Unit Tests: Isolate business logic
Integration Tests: Test full flow with DB and controllers
Use TestContainers for reproducible DB tests
Mock external services to avoid network calls
Test security and role-based access
Measure performance for heavy endpoints
Tip: Aim for >80% coverage in critical modules
✅ Unit testing with Mockito
✅ Controller & service integration tests
✅ TestContainers for database
✅ JWT-protected endpoint tests
✅ Performance monitoring basics
✅ Best practices for maintainable test suites
👉 Spring Boot Production Deployment & Optimization
We’ll cover:
Profiles and environment variables
Packaging and Dockerization
Cloud deployment (AWS / Azure / GCP)
Performance tuning and monitoring
✔ Write unit tests for all services
✔ Write integration tests for controllers
✔ Test endpoints with JWT authentication
✔ Add TestContainers for database
✔ Measure response times with Actuator