Web Application Testing

Comprehensive testing toolkit for the LucidData personal data bank MVP, integrating Playwright for end-to-end testing and Vitest for unit/integration testing.

Overview

This skill enables test-driven development (TDD) workflows for the LucidData Next.js application. It provides patterns for writing, running, and debugging tests across all layers: unit tests for utilities and services, integration tests for React components and API routes, and end-to-end tests for complete user workflows.

When to Use This Skill

Activate this skill when you need to:

• •Run test suites: Execute unit, integration, or E2E tests
• •Debug test failures: Investigate failing tests, review screenshots, check console logs
• •Write new tests: Create test files following LucidData patterns
• •Verify functionality: Test user flows like signup → vault creation → consent management
• •Check test coverage: Generate and analyze coverage reports (80% target)
• •Test responsive behavior: Validate UI across different viewports
• •Validate accessibility: Ensure WCAG compliance through automated tests

LucidData Testing Philosophy

The project follows a test pyramid approach:

• •Many unit tests: Fast, isolated tests for utilities, services, and pure functions
• •Some integration tests: Tests for React components with hooks, API route handlers
• •Few E2E tests: Critical user journeys (auth, core workflows)

Coverage targets: 80% for lines, functions, branches, and statements.

Test naming conventions:

• •Unit/Integration: *.test.ts or *.test.tsx
• •E2E: *.spec.ts

Test Infrastructure

Vitest (Unit & Integration Testing)

Configuration: vitest.config.ts

Key settings:

• •Environment: jsdom (simulates browser DOM)
• •Setup file: test/setup.ts
• •Global test functions: describe, it, expect available everywhere
• •Excludes E2E tests: __tests__/e2e/** directory excluded
• •Coverage: v8 provider with 80% thresholds
• •Timeouts: 10000ms for tests and hooks

Test utilities:

• •Mocks: test/mocks/prisma.ts, test/mocks/supabase.ts
• •Fixtures: test/fixtures/ (sample data factories)
• •Helpers: test/utils/ and test/helpers/

Libraries:

• •@testing-library/react: Component testing with queries and user events
• •@testing-library/jest-dom: Custom matchers (e.g., toBeInTheDocument())
• •@testing-library/user-event: Simulate user interactions
• •vitest-mock-extended: Advanced mocking with DeepMockProxy
• •msw: Mock Service Worker for API request interception

Playwright (E2E Testing)

Configuration: playwright.config.ts

Key settings:

• •Test directory: __tests__/e2e
• •Global setup: tests/e2e/global-setup.ts
• •Global teardown: tests/e2e/global-teardown.ts
• •Base URL: http://localhost:3000
• •Parallel execution: Enabled
• •Browsers: Chromium, Firefox, WebKit, Mobile Chrome (Pixel 5), Mobile Safari (iPhone 12)
• •Web server: Auto-starts Next.js dev server before tests
• •Screenshots: On failure
• •Videos: On first retry
• •Traces: On first retry

Helpers:

• •Auth helper: tests/e2e/helpers/auth.ts
  • •login(), signup(), logout(), isAuthenticated(), getUniqueEmail(), clearSession()
• •Data generators: tests/e2e/helpers/data-generators.ts
  • •generateVaultEntry(), generateConsent(), generateVaultEntries(count)

Common Testing Patterns

Unit Testing Pattern (Vitest)

import { describe, it, expect, vi } from 'vitest';

describe('UtilityFunction', () => {
  it('should perform expected operation', () => {
    const result = utilityFunction('input');
    expect(result).toBe('expected output');
  });

  it('should handle edge cases', () => {
    const result = utilityFunction('');
    expect(result).toBe('default value');
  });
});

Example from LucidData (lib/crypto/tests/hashing.test.ts):

describe('hash', () => {
  it('should produce SHA-256 hex string', () => {
    const hashed = hash('test data');
    expect(typeof hashed).toBe('string');
    expect(hashed).toHaveLength(64);
    expect(hashed).toMatch(/^[a-f0-9]{64}$/);
  });

  it('should be deterministic', () => {
    const hash1 = hash('data');
    const hash2 = hash('data');
    expect(hash1).toBe(hash2);
  });
});

Integration Testing Pattern (React Components)

import { render, screen } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import { vi } from 'vitest';

vi.mock('@/lib/db/prisma', () => ({
  prisma: prismaMock,
}));

describe('ComponentName', () => {
  it('should render correctly', () => {
    render(<ComponentName />);
    expect(screen.getByText('Expected Text')).toBeInTheDocument();
  });

  it('should handle user interaction', async () => {
    const user = userEvent.setup();
    render(<ComponentName />);

    await user.click(screen.getByRole('button', { name: 'Submit' }));
    expect(mockFunction).toHaveBeenCalled();
  });
});

Example from LucidData (repository tests):

import { prismaMock } from '@/test/mocks/prisma';

describe('VaultRepository', () => {
  beforeEach(() => {
    repository = new VaultRepository();
    vi.clearAllMocks();
  });

  it('should return vault entries for a user', async () => {
    prismaMock.vaultData.findMany.mockResolvedValue(userEntries);
    const result = await repository.findByUserId(userId);

    expect(result).toEqual(userEntries);
    expect(prismaMock.vaultData.findMany).toHaveBeenCalledWith({
      where: { userId },
      orderBy: { createdAt: 'desc' },
    });
  });
});

E2E Testing Pattern (Playwright)

import { test, expect } from '@playwright/test';

test.describe('Feature Flow', () => {
  test.beforeEach(async ({ page }) => {
    await clearSession(page);
  });

  test('should complete user workflow', async ({ page }) => {
    await page.goto('/feature-page');

    // Fill form
    await page.fill('input[name="field"]', 'value');
    await page.click('button[type="submit"]');

    // Verify result
    await expect(page.locator('text=Success')).toBeVisible();
  });
});

Example from LucidData (tests/e2e/auth/signup.spec.ts):

test.describe('Signup Flow', () => {
  test('should successfully create account', async ({ page }) => {
    await page.goto('/signup');
    const email = getUniqueEmail();

    await page.fill('input[name="email"]', email);
    await page.fill('input[name="password"]', TEST_USER.password);
    await page.click('button[type="submit"]');

    await expect(page).toHaveURL('/dashboard', { timeout: 10000 });
    await expect(page.locator(`text=${email}`)).toBeVisible();
  });
});

Test Commands

Unit & Integration Tests (Vitest)

# Watch mode (re-runs on file changes)
npm run test

# Single run (for CI/CD)
npm run test:run

# With coverage report
npm run test:coverage

# UI mode (visual test runner)
npm run test:ui

# Run specific test file
npx vitest run path/to/test.test.ts

# Run tests matching pattern
npx vitest run --grep "VaultRepository"

E2E Tests (Playwright)

# Headless mode (no browser UI)
npm run test:e2e

# Headed mode (see browser)
npm run test:e2e:headed

# UI mode (interactive)
npm run test:e2e:ui

# Debug mode (step through tests)
npm run test:e2e:debug

# Run specific test file
npx playwright test __tests__/e2e/auth/signup.spec.ts

# Run specific browser
npx playwright test --project=chromium

# Run specific test by name
npx playwright test --grep "should successfully create account"

All Tests

# Run all test suites (unit, integration, E2E)
npm run test:all

Debugging Test Failures

Step-by-Step Debugging Process

1. •Read test output: Identify the failing test and assertion error
2. •Check screenshots: E2E failures auto-save screenshots in test-results/
3. •Review browser logs: Playwright captures console.log, console.error messages
4. •Use interactive debugging:
   • •Vitest: Add vi.debug() to inspect values
   • •Playwright: Add await page.pause() for interactive debugging
5. •Verify test fixtures/mocks: Ensure mock data matches expected structure
6. •Check environment variables: Verify .env.test has correct configuration
7. •Isolate the issue: Run only the failing test with --grep flag

Common Issues & Solutions

Issue: "Element not found" in E2E test

• •Cause: Selector changed or element not rendered yet
• •Solution: Use await expect(element).toBeVisible() or increase timeout

Issue: "React Query mutation not called" in integration test

• •Cause: Mock setup timing issue
• •Solution: Use await waitFor() from @testing-library/react

Issue: "Prisma method not mocked"

• •Cause: Missing mock setup for database call
• •Solution: Add prismaMock.model.method.mockResolvedValue() in test setup

Issue: Test timeout

• •Cause: Async operation taking too long
• •Solution: Increase timeout in test config or use { timeout: 15000 } in specific test

LucidData-Specific Test Scenarios

Authentication Tests

• •Signup flow: Create account → Redirect to dashboard
• •Login flow: Enter credentials → Successful login
• •Logout flow: Click logout → Redirect to landing page
• •Protected routes: Access dashboard without auth → Redirect to login

Location: __tests__/e2e/auth/

Vault CRUD Tests

• •Create vault entry: Fill form → Submit → Entry appears in list
• •Read vault entry: Click entry → View dialog shows data
• •Update vault entry: Edit form → Save → Changes reflected
• •Delete vault entry: Click delete → Confirm → Entry removed

Location: __tests__/e2e/vault/

Consent Management Tests

• •Grant consent: Create consent → Set permissions → Save
• •View consent: Open consent list → See active/revoked consents
• •Revoke consent: Click revoke → Confirm → Status updated
• •Filter consents: Apply filters → List updates

Location: __tests__/e2e/consent/ (when implemented)

Audit Log Tests

• •View audit log: Navigate to audit page → See log entries
• •Filter by event type: Select filter → Entries update
• •Verify hash chain: Check hash integrity across entries

Location: __tests__/e2e/audit/ (when implemented)

Responsive Design Tests

Test UI across viewports:

• •Mobile: 375px, 390px (iPhone SE, iPhone 12)
• •Tablet: 768px, 1024px (iPad, iPad Pro)
• •Desktop: 1920px, 2560px (HD, QHD)

test('should be responsive on mobile', async ({ page }) => {
  await page.setViewportSize({ width: 375, height: 667 });
  await page.goto('/dashboard');
  // Verify mobile layout
});

Accessibility Tests

• •Keyboard navigation: Tab through forms, activate buttons with Enter
• •Screen reader labels: Check ARIA attributes, alt text
• •Color contrast: Automated checks with axe-core (future integration)

Test Data Management

Using Fixtures

Import pre-built data from test/fixtures/:

import { mockVaultEntry, createMockVaultEntries } from '@/test/fixtures/vault-data';

// Use single entry
const entry = mockVaultEntry;

// Generate multiple entries
const entries = createMockVaultEntries(5, 'user-id-123');

E2E Data Generators

For E2E tests, use helper functions to create unique test data:

import { generateVaultEntry } from '@/__tests__/e2e/helpers/data-generators';

const entry = generateVaultEntry({
  label: 'Test Entry',
  category: 'Identity',
});

Cleanup After E2E Tests

Global teardown (tests/e2e/global-teardown.ts) handles cleanup. For manual cleanup:

test.afterEach(async ({ page }) => {
  // Delete test data created during test
  await clearTestData(page);
});

Writing New Tests

1. Decide Test Type

• •Unit test: Testing a single function/utility in isolation
• •Integration test: Testing components with hooks, API routes with database calls
• •E2E test: Testing complete user workflows across multiple pages

2. Choose Location

• •Unit: lib/**/__tests__/utility.test.ts
• •Integration: components/**/__tests__/component.test.tsx or lib/**/__tests__/service.test.ts
• •E2E: __tests__/e2e/feature/flow.spec.ts

3. Follow Existing Patterns

Look at similar existing tests for structure, mock setup, and assertion patterns.

4. Use Descriptive Test Names

// Good
it('should encrypt data with AES-256-GCM')
it('should redirect to login when not authenticated')

// Bad
it('works')
it('test encryption')

5. Arrange-Act-Assert (AAA) Pattern

it('should create vault entry', async () => {
  // Arrange: Set up test data and mocks
  const input = { label: 'Test', category: 'Identity' };
  prismaMock.vaultData.create.mockResolvedValue(mockEntry);

  // Act: Execute the function under test
  const result = await vaultService.create(input);

  // Assert: Verify the outcome
  expect(result).toEqual(mockEntry);
  expect(prismaMock.vaultData.create).toHaveBeenCalledWith({
    data: expect.objectContaining(input),
  });
});

Best Practices

1. •Isolate tests: Each test should be independent, not relying on other tests' state
2. •Use realistic data: Fixtures should resemble production data (but never use real PII)
3. •Mock external dependencies: Mock Prisma, Supabase, API calls for unit/integration tests
4. •Test error paths: Don't just test happy paths; verify error handling
5. •Keep tests fast: Unit tests should run in milliseconds, integration tests in seconds
6. •Avoid test pollution: Clean up mocks with vi.clearAllMocks() in beforeEach()
7. •Use semantic queries: Prefer getByRole, getByLabelText over getByTestId
8. •Wait for async updates: Use await waitFor() or await expect().toBeVisible() for async operations

Coverage Analysis

Generate coverage report:

npm run test:coverage

Coverage report location: coverage/index.html (open in browser)

Interpreting coverage:

• •Green: Above 80% threshold
• •Yellow: 50-80% coverage
• •Red: Below 50% coverage

Focus on:

• •Lines: Percentage of code lines executed
• •Functions: Percentage of functions called
• •Branches: Percentage of if/else paths tested
• •Statements: Percentage of statements executed

Note: 100% coverage doesn't guarantee bug-free code. Focus on testing critical paths and edge cases.

Environment Configuration

Test environment uses .env.test file:

NEXT_PUBLIC_SUPABASE_URL=http://localhost:54321
SUPABASE_SERVICE_ROLE_KEY=<test-key>
DATABASE_URL=postgresql://postgres:postgres@localhost:54322/postgres
ENCRYPTION_KEY=eugsb9sWIyEOcEg5AzHazv0k7CMTjSsGfL1lbLp8duU=
NEXT_PUBLIC_APP_URL=http://localhost:3000
NODE_ENV=test

Important: Never commit real keys or sensitive data to version control.

References

For more detailed information, see:

• •Playwright Patterns - Page objects, selectors, authentication helpers
• •Vitest Patterns - Component testing, mocking strategies, async patterns
• •Test Data - Fixture structure, sample data, test credentials

Unified Test Runner Script

For convenience, use the run-tests.sh script:

# Run unit tests
./scripts/run-tests.sh unit

# Run E2E tests
./scripts/run-tests.sh e2e

# Run all tests
./scripts/run-tests.sh all

# With coverage
./scripts/run-tests.sh unit --coverage

Quick Reference

Version: 1.0 Last Updated: 2026-01-13 Maintained by: LucidData Team