testing

Testing Software

MCP Tools

Chrome DevTools (E2E testing):

• Automate user flows in real browser
• Capture screenshots for visual regression
• Run Lighthouse for accessibility testing
• Profile performance during test runs

Testing Pyramid

1. Unit Tests (Many): Fast, isolated, test single units
2. Integration Tests (Some): Test component interactions
3. E2E Tests (Few): Test complete user flows — use Chrome DevTools

Workflows

• Analyze: Use Glob and Grep to identify untested code
• Unit Tests: Cover all public functions
• Edge Cases: Test boundaries and error conditions
• Integration: Test external dependencies
• E2E: Use Chrome DevTools for browser automation
• Regression: Add test for each bug fix

Test Quality Standards

Deterministic

Tests must produce the same result every time.

Isolated

Tests should not depend on each other or shared state.

Clear

Test names should describe the behavior being tested.

Test Patterns

Arrange-Act-Assert (AAA) (Java + JUnit 5)

@ExtendWith(MockitoExtension.class)
class UserServiceTest {
    @Mock
    private EmailService emailService;

    @InjectMocks
    private UserService userService;

    @Test
    void registerUser_ValidEmail_SendsWelcomeEmail() {
        // Arrange
        String email = "[email protected]";
        ArgumentCaptor<Email> emailCaptor = ArgumentCaptor.forClass(Email.class);

        // Act
        userService.register(email);

        // Assert
        verify(emailService).send(emailCaptor.capture());
        Email sentEmail = emailCaptor.getValue();
        assertThat(sentEmail.getTo()).isEqualTo("[email protected]");
        assertThat(sentEmail.getSubject()).isEqualTo("Welcome!");
    }
}

E2E Testing with Chrome DevTools

// Use Chrome DevTools MCP for browser automation
// - Navigate to pages
// - Fill forms and click buttons
// - Capture screenshots for visual regression
// - Run Lighthouse accessibility audits
// - Check console for errors

Commands (Java/Maven)

# Run unit tests
mvn test

# Run tests with coverage
mvn verify

# Run specific test class
mvn test -Dtest=UserServiceTest

# Run specific test method
mvn test -Dtest=UserServiceTest#registerUser_ValidEmail_SendsWelcomeEmail

# Generate coverage report
mvn jacoco:report

# View coverage report
open target/site/jacoco/index.html

Finding Untested Code

Use Glob and Grep to identify gaps:

1. Use Glob to find all source files and test files
2. Check which source files have corresponding test files
3. Use Grep to see if functions are referenced in tests