Hackforge Academy

Explanation

JUnit 5 is the standard testing framework for Java applications. It helps verify individual methods and business logic by writing automated test cases, ensuring code quality and preventing regressions during application development.

Code:

@Test
void shouldReturnStudentName() {
    Student student = new Student("John");
    assertEquals("John", student.getName());
}

Explanation

Mockito creates mock objects for dependencies, allowing service classes to be tested independently of databases or external systems. This makes unit tests faster, isolated, and focused on business logic rather than infrastructure.

Code:

@ExtendWith(MockitoExtension.class)
class StudentServiceTest {

    @Mock
    private StudentRepository repository;

    @InjectMocks
    private StudentService service;
}

Explanation

MockMvc simulates HTTP requests without starting a real web server. It allows developers to test REST controllers, verify HTTP status codes, response bodies, headers, and JSON content quickly during automated testing.

Code:

@Autowired
private MockMvc mockMvc;

@Test
void shouldReturnStudents() throws Exception {
    mockMvc.perform(get("/students"))
           .andExpect(status().isOk());
}

Explanation

Testcontainers runs real Docker containers for databases and other services during tests. This provides realistic integration testing environments, ensuring application behavior matches production without requiring permanent local installations.

Code:

@Container
static PostgreSQLContainer<?> postgres =
    new PostgreSQLContainer<>("postgres:16");

Explanation

Use JUnit 5 for unit tests, Mockito for mocking dependencies, MockMvc for testing REST endpoints, and Testcontainers for integration tests with real databases. Combining these tools ensures reliable, maintainable, and production-ready Spring Boot applications.

Code:

JUnit 5
   ↓
Mockito
   ↓
MockMvc
   ↓
Testcontainers
   ↓
Reliable Spring Boot Testing