Testing is the backbone of any robust Spring Boot application. Yet, many developers make avoidable mistakes that lead to flaky, slow, or unreliable tests.

If you’ve ever faced issues like tests randomly failing, slow build times, or struggling with mocks, this post is for you!

Let’s dive into the best practices that will ensure your Spring Boot tests are fast, reliable, and maintainable.

1. Use the Right Testing Strategy

Spring Boot offers different testing approaches, and using the wrong one can make your tests unnecessarily slow or unreliable.

Unit Tests: Focus on testing individual components (e.g., services, repositories) without Spring Context.

Integration Tests: Test how different components interact using an embedded database or mock dependencies.

End-to-End (E2E) Tests: Validate the entire application behavior, including database and external services.

Check out Spring’s official testing documentation for more insights.

2. Avoid Loading the Entire Spring Context Unnecessarily

A common mistake is using @SpringBootTest for every test. This loads the entire application context, making tests slow.

Use @SpringBootTest only when absolutely necessary (like testing controllers or full integration tests).

For unit tests, mock dependencies instead. Use @MockBean to replace actual beans with mocks.

@RunWith(MockitoJUnitRunner.class) 
public class UserServiceTest { 

    @InjectMocks 
    private UserService userService; 

    @Mock 
    private UserRepository userRepository; 

    @Test 
    public void testFindUserById() { 
        when(userRepository.findById(1L)).thenReturn(Optional.of(new User(1L, "John Doe"))); 
        User user = userService.findUserById(1L); 
        assertEquals("John Doe", user.getName()); 
    } 
} 

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3. Use TestContainers for Reliable Database Testing

If your tests depend on a real database, avoid using H2 for everything—it doesn’t always behave like production databases (like PostgreSQL or MySQL).

Instead, use TestContainers to spin up lightweight, disposable databases.

Example: Using TestContainers with Spring Boot

@Container 
public static PostgreSQLContainer<?> postgres =  
    new PostgreSQLContainer<>("postgres:13") 
        .withDatabaseName("testdb") 
        .withUsername("testuser") 
        .withPassword("testpass"); 

@BeforeAll 
static void setup() { 
    System.setProperty("DB_URL", postgres.getJdbcUrl()); 
    System.setProperty("DB_USERNAME", postgres.getUsername()); 
    System.setProperty("DB_PASSWORD", postgres.getPassword()); 
} 

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4. Use MockMvc for Controller Tests Instead of Starting a Server

Many developers start a full server for controller tests, which slows down execution. Use MockMvc instead to test REST APIs efficiently.

@WebMvcTest(UserController.class) 
public class UserControllerTest { 

    @Autowired 
    private MockMvc mockMvc; 

    @MockBean 
    private UserService userService; 

    @Test 
    public void shouldReturnUser() throws Exception { 
        when(userService.findUserById(1L)).thenReturn(new User(1L, "John Doe")); 

        mockMvc.perform(get("/users/1")) 
               .andExpect(status().isOk()) 
               .andExpect(jsonPath("$.name").value("John Doe")); 
    } 
} 

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Read more on MockMvc in Spring Boot

5. Use @DataJpaTest for Repository Testing

When testing JPA repositories, use @DataJpaTest to load only the required components, making the tests much faster.

@DataJpaTest 
public class UserRepositoryTest { 

    @Autowired 
    private UserRepository userRepository; 

    @Test 
    public void shouldSaveAndRetrieveUser() { 
        User user = new User(null, "Alice"); 
        User savedUser = userRepository.save(user); 
        assertNotNull(savedUser.getId()); 
    } 
} 

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Want to know more? Check out Spring Data JPA documentation.

6. Keep Your Tests Fast & Isolated

Slow tests = frustrated developers. Here’s how to speed them up:

Parallelize Tests: Use @DirtiesContext sparingly, as it reloads the context.

Mock External Services: Use WireMock or Mockito to avoid calling real APIs.

Use In-Memory Databases Cautiously: Great for simple tests but may not reflect production behavior.

Learn more about test optimization strategies here.

7. CI/CD: Run the Right Tests at the Right Time

In Continuous Integration/Continuous Deployment (CI/CD) pipelines, not all tests need to run all the time.

Unit Tests: Run on every commit (fast and frequent).

Integration Tests: Run on PRs to ensure components work together.

E2E Tests: Run before deployment for final validation.

Need help setting up testing in CI/CD? Check this GitHub Actions guide.

8. Use Allure Reports for Better Test Visualization

Want to impress your team with professional test reports?

Use Allure Reports for detailed test results with graphs and screenshots.

Final Thoughts

By following these best practices, you’ll ensure your Spring Boot tests are fast, reliable, and effective.

Which testing challenge have you faced the most? Drop your thoughts in the comments! Let’s discuss.

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原文链接：Are You Making These Mistakes in Spring Boot Testing? Best Practices You Need to Know!