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Overview

The User Management System uses JUnit 5, Mockito, and Spring Boot Test for comprehensive testing coverage. Tests are organized into unit and integration tests, with JaCoCo providing code coverage reports.

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Running Tests

1

Run all tests

Execute the complete test suite using Maven:
mvn test
This command runs all unit and integration tests and generates a JaCoCo coverage report.
2

Run specific test class

To run a specific test class:
mvn test -Dtest=UserServiceImplTest
3

View coverage report

After running tests, open the JaCoCo HTML report:
open target/site/jacoco/index.html
The report is located at target/site/jacoco/index.html

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Test Structure

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Unit Tests

Unit tests verify individual components in isolation using mocks. Located in src/test/java/.../unit/
Tests the core user service business logic with mocked dependencies.Location: src/test/java/dev/juanJe/userManagementSystem/unit/service/UserServiceImplTest.javaKey test cases:
  • User registration with valid data
  • Duplicate user detection (username/email)
  • User authentication with valid credentials
  • Authentication failure with invalid credentials
  • User info retrieval
  • Password verification
  • List all users
@Test
@DisplayName("registerUser() Should register a user successfully")
void shouldRegisterUserSuccessfully() {
    CreateUserDTO dto = new CreateUserDTO();
    dto.setUsername("Juan");
    dto.setEmail("[email protected]");
    dto.setPassword("1234");
    
    when(userRepository.existsByEmail("[email protected]")).thenReturn(false);
    when(userRepository.existsByUsername("Juan")).thenReturn(false);
    
    SignupResponseDTO response = userServiceImpl.registerUser(dto);
    
    assertEquals("Juan", response.getUsername());
    assertNotNull(response.getId());
}
Tests JWT token generation and validation.Location: src/test/java/dev/juanJe/userManagementSystem/unit/security/JwtUtilTest.javaKey test cases:
  • Token generation with username and role
  • Token validation and claims extraction
  • Invalid token handling
@Test
@DisplayName("Should generate and validate token successfully")
void shouldGenerateAndValidateTokenSuccessfully() {
    String token = jwtUtil.generateToken("Juan", "ROLE_USER");
    
    assertNotNull(token);
    assertEquals("Juan", jwtUtil.getUsernameFromToken(token));
    assertEquals("ROLE_USER", jwtUtil.getRoleFromToken(token));
}
Tests the error response data structure.Location: src/test/java/dev/juanJe/userManagementSystem/unit/dto/ErrorResponseDTOTest.javaKey test cases:
  • Constructor initialization
  • Automatic timestamp generation
  • Error list handling

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Integration Tests

Integration tests verify component interactions. Located in src/test/java/.../integration/
Tests the JWT authentication filter in the security chain.Location: src/test/java/dev/juanJe/userManagementSystem/integration/security/JwtAuthenticationFilterTest.javaKey test cases:
  • Authentication with valid JWT token
  • Request handling without token
  • Security context population
@Test
@DisplayName("Should authenticate when valid token present")
void shouldAuthenticateWhenValidTokenPresent() throws Exception {
    String token = "valid.jwt.token";
    
    when(request.getHeader("Authorization")).thenReturn("Bearer " + token);
    when(jwtUtil.getUsernameFromToken(token)).thenReturn("Juan");
    when(jwtUtil.getRoleFromToken(token)).thenReturn("ROLE_USER");
    
    jwtAuthenticationFilter.doFilter(request, response, filterChain);
    
    assertNotNull(SecurityContextHolder.getContext().getAuthentication());
    assertEquals("Juan", SecurityContextHolder.getContext().getAuthentication().getPrincipal());
}

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JaCoCo Coverage Reports

JaCoCo is configured in the Maven build to automatically generate coverage reports.

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Configuration

The JaCoCo plugin is configured in pom.xml:108-125: 
<plugin>
    <groupId>org.jacoco</groupId>
    <artifactId>jacoco-maven-plugin</artifactId>
    <version>0.8.10</version>
    <executions>
        <execution>
            <goals>
                <goal>prepare-agent</goal>
            </goals>
        </execution>
        <execution>
            <id>report</id>
            <phase>test</phase>
            <goals>
                <goal>report</goal>
            </goals>
        </execution>
    </executions>
</plugin>

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Reading Coverage Reports

The HTML report shows:
  • Line coverage: Percentage of code lines executed
  • Branch coverage: Percentage of conditional branches tested
  • Method coverage: Percentage of methods invoked
  • Class coverage: Percentage of classes tested
Coverage reports are generated automatically during mvn test and are located in target/site/jacoco/

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Test Dependencies

Key testing dependencies from pom.xml: 
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-test</artifactId>
    <scope>test</scope>
</dependency>

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Best Practices

1

Use descriptive test names

Use @DisplayName annotations to clearly describe what each test verifies:
@DisplayName("registerUser() Should throw exception when user already exists")
2

Organize with test ordering

Use @TestMethodOrder and @Order for logical test execution:
@TestMethodOrder(MethodOrderer.OrderAnnotation.class)
public class UserServiceImplTest {
    @Test
    @Order(1)
    void shouldRegisterUserSuccessfully() { ... }
}
3

Mock external dependencies

Use @Mock and @InjectMocks for clean dependency injection:
@Mock
private UserRepository userRepository;

@InjectMocks
private UserServiceImpl userServiceImpl;
4

Verify interactions

Always verify that mocked methods were called as expected:
verify(userRepository).findByEmail("[email protected]");
verify(passwordEncoder).matches("123456", "encodedPassword");

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Running Tests in CI/CD

For continuous integration pipelines: 
# Run tests with coverage
mvn clean test

# Package application (runs tests automatically)
mvn clean package

# Skip tests if needed (not recommended)
mvn clean package -DskipTests
The mvn package command automatically runs all tests before creating the JAR file.

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