testing-strategies

testing-strategies

Testing Strategies When to use this skill New project: define a testing strategy Quality issues: bugs happen frequently Before refactoring: build a safety net CI/CD setup: automated tests Instructions Step 1: Understand the Test Pyramid /\ /E2E\ ← few (slow, expensive) /\ / \ /Integration\ ← medium /____\ / \ / Unit Tests \ ← many (fast, inexpensive) /______________\ Ratio guide: Unit: 70% Integration: 20% E2E: 10% Step 2: Unit testing strategy Given-When-Then pattern: describe('calculateDiscount', () => { it('should apply 10% discount for orders over $100', () => { // Given: setup const order = { total: 150, customerId: '123' }; // When: perform action const discount = calculateDiscount(order); // Then: verify result expect(discount).toBe(15); }); it('should not apply discount for orders under $100', () => { const order = { total: 50, customerId: '123' }; const discount = calculateDiscount(order); expect(discount).toBe(0); }); it('should throw error for invalid order', () => { const order = { total: -10, customerId: '123' }; expect(() => calculateDiscount(order)).toThrow('Invalid order'); }); }); Mocking strategy: // Mock external dependencies jest.mock('../services/emailService'); import { sendEmail } from '../services/emailService'; describe('UserService', () => { it('should send welcome email on registration', async () => { // Arrange const mockSendEmail = sendEmail as jest.MockedFunction; mockSendEmail.mockResolvedValueOnce(true); // Act await userService.register({ email: 'test@example.com', password: 'pass' }); // Assert expect(mockSendEmail).toHaveBeenCalledWith({ to: 'test@example.com', subject: 'Welcome!', body: expect.any(String) }); }); }); Step 3: Integration Testing API endpoint tests: describe('POST /api/users', () => { beforeEach(async () => { await db.user.deleteMany(); // Clean DB }); it('should create user with valid data', async () => { const response = await request(app) .post('/api/users') .send({ email: 'test@example.com', username: 'testuser', password: 'Password123!' }); expect(response.status).toBe(201); expect(response.body.user).toMatchObject({ email: 'test@example.com', username: 'testuser' }); // Verify it was actually saved to the DB const user = await db.user.findUnique({ where: { email: 'test@example.com' } }); expect(user).toBeTruthy(); }); it('should reject duplicate email', async () => { // Create first user await request(app) .post('/api/users') .send({ email: 'test@example.com', username: 'user1', password: 'Pass123!' }); // Attempt duplicate const response = await request(app) .post('/api/users') .send({ email: 'test@example.com', username: 'user2', password: 'Pass123!' }); expect(response.status).toBe(409); }); }); Step 4: E2E Testing (Playwright) import { test, expect } from '@playwright/test'; test.describe('User Registration Flow', () => { test('should complete full registration process', async ({ page }) => { // 1. Visit homepage await page.goto('http://localhost:3000'); // 2. Click Sign Up button await page.click('text=Sign Up'); // 3. Fill out form await page.fill('input[name="email"]', 'test@example.com'); await page.fill('input[name="username"]', 'testuser'); await page.fill('input[name="password"]', 'Password123!'); // 4. Submit await page.click('button[type="submit"]'); // 5. Confirm success message await expect(page.locator('text=Welcome')).toBeVisible(); // 6. Confirm redirect to dashboard await expect(page).toHaveURL('http://localhost:3000/dashboard'); // 7. Confirm user info is displayed await expect(page.locator('text=testuser')).toBeVisible(); }); test('should show error for invalid email', async ({ page }) => { await page.goto('http://localhost:3000/signup'); await page.fill('input[name="email"]', 'invalid-email'); await page.fill('input[name="password"]', 'Password123!'); await page.click('button[type="submit"]'); await expect(page.locator('text=Invalid email')).toBeVisible(); }); }); Step 5: TDD (Test-Driven Development) Red-Green-Refactor Cycle: // 1. RED: write a failing test describe('isPalindrome', () => { it('should return true for palindrome', () => { expect(isPalindrome('racecar')).toBe(true); }); }); // 2. GREEN: minimal code to pass the test function isPalindrome(str: string): boolean { return str === str.split('').reverse().join(''); } // 3. REFACTOR: improve the code function isPalindrome(str: string): boolean { const cleaned = str.toLowerCase().replace(/[^a-z0-9]/g, ''); return cleaned === cleaned.split('').reverse().join(''); } // 4. Additional test cases it('should ignore case and spaces', () => { expect(isPalindrome('A man a plan a canal Panama')).toBe(true); }); it('should return false for non-palindrome', () => { expect(isPalindrome('hello')).toBe(false); }); Output format Testing strategy document ## Testing Strategy ### Coverage Goals - Unit Tests: 80% - Integration Tests: 60% - E2E Tests: Critical user flows ### Test Execution - Unit: Every commit (local + CI) - Integration: Every PR - E2E: Before deployment ### Tools - Unit: Jest - Integration: Supertest - E2E: Playwright - Coverage: Istanbul/nyc ### CI/CD Integration - GitHub Actions: Run all tests on PR - Fail build if coverage < 80% - E2E tests on staging environment Constraints Required rules (MUST) Test isolation: each test is independent Fast feedback: unit tests should be fast (<1 min) Deterministic: same input → same result Prohibited items (MUST NOT) Test dependencies: do not let test A depend on test B Production DB: do not use a real DB in tests Sleep/Timeout: avoid time-based tests Best practices AAA pattern: Arrange-Act-Assert Test names: "should ... when ..." Edge Cases: boundary values, null, empty values Happy Path + Sad Path: both success/failure scenarios References Test Pyramid Jest Playwright Testing Best Practices Metadata Version Current version: 1.0.0 Last updated: 2025-01-01 Compatible platforms: Claude, ChatGPT, Gemini Related skills backend-testing code-review Tags #testing #test-strategy #TDD #unit-test #integration-test #E2E #code-quality Examples Example 1: Basic usage Example 2: Advanced usageWeekly Installs10.7KRepositorysupercent-io/sk…templateGitHub Stars53First SeenJan 24, 2026Security AuditsGen Agent Trust HubPassSocketPassSnykPassInstalled oncodex10.7Kgemini-cli10.7Kopencode10.6Kgithub-copilot10.6Kcursor10.6Kcline10.6K