---
name: testing
description: Write effective tests for code quality and reliability. Use when implementing features, fixing bugs, or improving coverage. Covers unit, integration, and E2E testing.
allowed-tools: Read, Write, Edit, Bash, Glob, Grep, mcp__chrome-devtools__*
---

# 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)

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

    @InjectMocks
    private UserService userService;

    @Test
    void registerUser_ValidEmail_SendsWelcomeEmail() {
        // Arrange
        String email = "test@example.com";
        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("test@example.com");
        assertThat(sentEmail.getSubject()).isEqualTo("Welcome!");
    }
}
```

## E2E Testing with Chrome DevTools

```javascript
// 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)

```bash
# 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