AI-Powered Testing and Quality Assurance

Transform Your Testing Workflow with AI

Testing is where AI assistance truly shines. Instead of manually writing repetitive test cases or struggling to achieve coverage goals, Cursor’s AI can generate comprehensive test suites, debug failures, and even perform end-to-end testing through browser automation.

Wskazówka

The AI Testing Advantage
AI excels at:

• Generating edge cases you might miss
• Writing tests that actually verify behavior
• Maintaining consistency across test suites
• Debugging test failures automatically

Test-Driven Development with AI

The traditional TDD cycle (Red → Green → Refactor) becomes supercharged with AI assistance. Here’s the enhanced workflow:

1. Write Tests First

AI generates comprehensive test cases from requirements

2. Run Tests (Red)

Tests fail initially - this validates they’re testing real behavior

3. Implement Code (Green)

AI writes code to make tests pass, iterating automatically

4. Refactor (Blue)

AI optimizes code while ensuring tests still pass

The Power of YOLO Mode for Testing

Enable YOLO mode to unlock automated test execution:

Settings → General → YOLO Mode → Enable

Recommended prompt:
any kind of tests are always allowed like vitest, npm test,
nr test, etc. also basic build commands like build, tsc, etc.
creating files and making directories (like touch, mkdir, etc)
is always ok too

With YOLO mode, Agent can:

• Run tests automatically
• Fix failing tests by updating code
• Iterate until all tests pass
• Fix TypeScript/linting errors

Example: Building a Function with TDD

Let’s implement a complex function using AI-powered TDD:

Agent: Create a function that converts markdown to HTML.
Write tests first, then the code, then run the tests
and update the code until tests pass.

Watch as Agent:

1. Creates comprehensive test file

   describe('markdownToHtml', () => {
     it('should convert headers', () => {
       expect(markdownToHtml('# Title')).toBe('<h1>Title</h1>');
       expect(markdownToHtml('## Subtitle')).toBe('<h2>Subtitle</h2>');
     });
   
     it('should convert bold text', () => {
       expect(markdownToHtml('**bold**')).toBe('<strong>bold</strong>');
     });
   
     it('should handle code blocks', () => {
       expect(markdownToHtml('`code`')).toBe('<code>code</code>');
     });
   
     // AI generates many more edge cases...
   });

2. Implements the function

   function markdownToHtml(markdown) {
     // Initial implementation
   }

3. Runs tests and sees failures

   ✗ 6 tests failed

4. Iteratively fixes the code

   Updating implementation to handle headers...
   Running tests again...
   ✗ 3 tests failed
   
   Adding bold text support...
   Running tests again...
   ✓ All tests passed!

Notatka

Pro Tip: If Agent goes off track, stop it and provide guidance: “Wait, focus on making the header tests pass first before moving to other features”

Unit Testing Patterns

Pattern 1: Component Testing (React/Vue/Angular)

React

Agent: Create unit tests for this UserProfile component.
Test all props, user interactions, and edge cases.
Use React Testing Library.

Agent generates:

describe('UserProfile', () => {
  it('renders user name and avatar', () => {
    const user = { name: 'John', avatar: 'url' };
    render(<UserProfile user={user} />);
    expect(screen.getByText('John')).toBeInTheDocument();
    expect(screen.getByRole('img')).toHaveAttribute('src', 'url');
  });

  it('handles missing avatar gracefully', () => {
    // Edge case testing
  });

  it('calls onEdit when edit button clicked', () => {
    // Interaction testing
  });
});

Node.js

Agent: Write comprehensive tests for this API endpoint.
Include success cases, error handling, and edge cases.

Agent creates:

describe('POST /api/users', () => {
  it('creates user with valid data', async () => {
    const response = await request(app)
      .post('/api/users')
      .send({ name: 'Test', email: 'test@example.com' });

    expect(response.status).toBe(201);
    expect(response.body).toHaveProperty('id');
  });

  it('validates email format', async () => {
    const response = await request(app)
      .post('/api/users')
      .send({ name: 'Test', email: 'invalid' });

    expect(response.status).toBe(400);
    expect(response.body.error).toContain('email');
  });

  // More test cases...
});

Pattern 2: Testing Async Operations

Agent: Create tests for this async data fetching function.
Include loading states, success, errors, and retries.

AI handles complex async scenarios:

describe('fetchUserData', () => {
  it('returns user data on success', async () => {
    const mockUser = { id: 1, name: 'Test' };
    fetch.mockResolvedValueOnce({
      ok: true,
      json: async () => mockUser
    });

    const result = await fetchUserData(1);
    expect(result).toEqual(mockUser);
  });

  it('retries on network failure', async () => {
    fetch.mockRejectedValueOnce(new Error('Network error'));
    fetch.mockResolvedValueOnce({
      ok: true,
      json: async () => ({ id: 1 })
    });

    const result = await fetchUserData(1);
    expect(fetch).toHaveBeenCalledTimes(2);
    expect(result).toBeDefined();
  });
});

E2E Testing with Browser Automation

Leverage Puppeteer/Playwright MCP for comprehensive E2E testing:

Setting Up Browser Testing

Agent: Set up E2E tests for our login flow using Puppeteer.
Test successful login, invalid credentials, and forgot password.

Uwaga

Ensure Puppeteer MCP is installed:

{
  "mcpServers": {
    "puppeteer": {
      "command": "npx",
      "args": ["-y", "@modelcontextprotocol/server-puppeteer"]
    }
  }
}

E2E Test Implementation

Agent creates comprehensive E2E tests:

describe('Login Flow E2E', () => {
  it('successful login redirects to dashboard', async () => {
    // Agent uses Puppeteer MCP
    await page.goto('http://localhost:3000/login');
    await page.type('#email', 'user@example.com');
    await page.type('#password', 'correct-password');
    await page.click('button[type="submit"]');

    await page.waitForNavigation();
    expect(page.url()).toContain('/dashboard');

    // Take screenshot for visual verification
    await page.screenshot({ path: 'login-success.png' });
  });

  it('shows error for invalid credentials', async () => {
    await page.goto('http://localhost:3000/login');
    await page.type('#email', 'user@example.com');
    await page.type('#password', 'wrong-password');
    await page.click('button[type="submit"]');

    const error = await page.waitForSelector('.error-message');
    const text = await error.evaluate(el => el.textContent);
    expect(text).toContain('Invalid credentials');
  });
});

Visual Regression Testing

Agent: Add visual regression tests for our key pages.
Compare screenshots and flag any visual changes.

Debugging Test Failures

When tests fail, AI becomes your debugging partner:

Strategic Debugging Workflow

1. Analyze Failure

Agent: This test is failing. Add console.logs
to understand what's happening.

2. Run with Logs

Agent runs test with added logging,
captures output for analysis

3. Identify Issue

Based on logs: "The issue is the date
format doesn't match expected pattern"

4. Fix and Verify

Agent fixes the code and reruns tests
to confirm resolution

Example Debugging Session

User: The user authentication test is failing intermittently

Agent: I'll debug this intermittent failure. Let me add logging
and timing information to understand the issue.

[Adds strategic console.logs and performance marks]
[Runs test multiple times]

Found it! The test fails when the database connection pool
is exhausted. The previous test isn't cleaning up connections.
Let me fix this by adding proper cleanup...

[Adds afterEach cleanup hook]
[Runs test 10 times - all pass]

The intermittent failure is now resolved.

Test Coverage and Quality Metrics

Achieving High Coverage

Agent: Analyze our test coverage and write tests
to reach 90% coverage for the auth module.

Agent will:

1. Run coverage report
2. Identify untested code paths
3. Generate tests for missing coverage
4. Focus on meaningful tests, not just line coverage

Coverage Report Analysis

File               | % Stmts | % Branch | % Funcs | % Lines |
-------------------|---------|----------|---------|---------|
auth/login.js      |   75.00 |    66.67 |  100.00 |   75.00 |
auth/register.js   |   90.00 |    85.00 |  100.00 |   88.89 |
auth/reset.js      |   45.00 |    33.33 |   66.67 |   45.00 |

Agent: I'll focus on auth/reset.js which has low coverage.
Creating tests for password reset edge cases...

Advanced Testing Patterns

Pattern 1: Mocking External Services

Agent: Mock all external API calls in our payment tests.
Include both success and failure scenarios.

// AI generates comprehensive mocks
jest.mock('@/services/stripe', () => ({
  createPaymentIntent: jest.fn(),
  confirmPayment: jest.fn(),
  handleWebhook: jest.fn()
}));

describe('Payment Processing', () => {
  beforeEach(() => {
    // Reset mocks between tests
    jest.clearAllMocks();
  });

  it('handles Stripe API errors gracefully', async () => {
    const stripeError = new Error('Card declined');
    stripeError.code = 'card_declined';

    createPaymentIntent.mockRejectedValueOnce(stripeError);

    // Test error handling...
  });
});

Pattern 2: Data-Driven Testing

Agent: Create data-driven tests for our validation logic.
Test with various input combinations.

describe('Input Validation', () => {
  const testCases = [
    { input: 'valid@email.com', expected: true, description: 'valid email' },
    { input: 'invalid.email', expected: false, description: 'missing @' },
    { input: '@example.com', expected: false, description: 'missing local part' },
    { input: 'test@', expected: false, description: 'missing domain' },
    // AI generates many more cases...
  ];

  testCases.forEach(({ input, expected, description }) => {
    it(`validates ${description}`, () => {
      expect(isValidEmail(input)).toBe(expected);
    });
  });
});

Performance and Load Testing

Agent: Create performance tests for our API endpoints.
Measure response times and identify bottlenecks.

describe('API Performance', () => {
  it('responds within 200ms for user list', async () => {
    const start = performance.now();
    const response = await request(app).get('/api/users');
    const duration = performance.now() - start;

    expect(response.status).toBe(200);
    expect(duration).toBeLessThan(200);
  });

  it('handles 100 concurrent requests', async () => {
    const requests = Array(100).fill(null).map(() =>
      request(app).get('/api/users')
    );

    const responses = await Promise.all(requests);
    const successCount = responses.filter(r => r.status === 200).length;

    expect(successCount).toBeGreaterThan(95); // 95% success rate
  });
});

Quality Gates and CI Integration

Automated Quality Checks

Agent: Set up quality gates that prevent merging if:
- Test coverage drops below 80%
- Any tests fail
- Performance benchmarks aren't met

Best Practices for AI-Assisted Testing

Test Behavior, Not Implementation

Focus on what the code does, not how it does it

Maintain Test Independence

Each test should run in isolation without dependencies

Use Descriptive Names

Test names should clearly describe what they verify

Keep Tests Simple

One assertion per test when possible

Troubleshooting Common Issues

Flaky Tests

Issue: Tests pass sometimes, fail others

Solution:
Agent: Debug this flaky test by running it 20 times
and identifying what varies between runs.

Slow Tests

Issue: Test suite takes too long

Solution:
Agent: Profile our test suite and identify the
slowest tests. Suggest optimizations.

False Positives

Issue: Tests pass but feature is broken

Solution:
Agent: Review these tests and identify why they're
not catching the actual bug. Strengthen assertions.

Next Steps

Your testing game is now transformed with AI assistance:

1. Aim for comprehensive coverage - Let AI find edge cases
2. Automate everything - From unit tests to E2E scenarios
3. Use tests as documentation - Well-written tests explain behavior
4. Integrate with CI/CD - Automated quality gates
5. Continuously improve - AI helps maintain and update tests

Wskazówka

Testing Excellence Achieved! 🎯
With AI-powered testing, you can achieve higher coverage, catch more bugs before production, and spend less time writing repetitive test code. Your code quality and confidence will soar!