name: testing
router_kit: FullStackKit
description: Comprehensive test strategies and 2025 test tools. Unit, integration, e2e and visual testing.
metadata:
skillport:
category: quality
tags: [architecture, automation, best practices, clean code, coding, collaboration, compliance, debugging, design patterns, development, documentation, efficiency, git, optimization, productivity, programming, project management, quality assurance, refactoring, software engineering, standards, testing, utilities, version control, workflow] - quality-assurance

Testing Skill - Quality Assurance and Test Strategies

Systematic test approaches for ensuring software quality.
2025 modern test tools and pyramid test strategy.

📋 Table of Contents

• Testing Skill - Quality Assurance and Test Strategies
• 📋 Table of Contents
• 1. Test Pyramid
• 2. Unit Testing (Jest)
• 2.1 Basic Test Structure
• 2.2 Mocking
• 3. Integration Testing
• 3.1 API Integration
• 4. E2E Testing (Playwright)
• 4.1 Login Flow
• 5. Visual Regression Testing
• 6. TDD (Test Driven Development)
• 7. Test Writing Rules
• 🔄 Workflow
  • Phase 1: Strategy \& Test Plan
  • Phase 2: Implementation \& Interaction
  • Phase 3: Verification \& CI/CD
  • Checkpoints

1. Test Pyramid

      / \
     /E2E\  ← Least (Slow, Expensive, Fragile)
    /-----\
   / INTEGR\ ← Medium (Balance of Speed and Confidence)
  /---------\
 /   UNIT    \ ← Most (Fast, Cheap, Isolated)
/-------------\

2. Unit Testing (Jest)

2.1 Basic Test Structure

import { sum } from './math';

describe('sum function', () => {
  test('adds 1 + 2 to equal 3', () => {
    expect(sum(1, 2)).toBe(3);
  });

  test('handles zero correctly', () => {
    expect(sum(0, 0)).toBe(0);
  });
});

2.2 Mocking

// Service mocking
jest.mock('./apiService');
import { fetchData } from './apiService';

test('should use mocked data', async () => {
  (fetchData as jest.Mock).mockResolvedValue({ id: 1, name: 'Test' });
  const data = await getServiceData();
  expect(data.name).toBe('Test');
});

3. Integration Testing

3.1 API Integration

import request from 'supertest';
import app from './app';

describe('POST /api/users', () => {
  test('should create a new user and return it', async () => {
    const response = await request(app)
      .post('/api/users')
      .send({ email: '[email protected]', name: 'Test' });

    expect(response.status).toBe(201);
    expect(response.body.email).toBe('[email protected]');
  });
});

4. E2E Testing (Playwright)

4.1 Login Flow

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

test('user can login successfully', async ({ page }) => {
  await page.goto('/login');
  await page.fill('input[name="email"]', '[email protected]');
  await page.fill('input[name="password"]', 'password123');
  await page.click('button[type="submit"]');

  await expect(page).toHaveURL('/dashboard');
  await expect(page.locator('h1')).toContainText('Hoş Geldiniz');
});

5. Visual Regression Testing

// Playwright visual test
test('dashboard visual comparison', async ({ page }) => {
  await page.goto('/dashboard');
  await expect(page).toHaveScreenshot('dashboard.png');
});

6. TDD (Test Driven Development)

1. RED: Write test and see it failing.
2. GREEN: Write minimum code required to pass the test.
3. REFACTOR: Clean up code and test, make it compliant with standards.

7. Test Writing Rules

• AAA Pattern: Arrange, Act, Assert.
• Isolation: Tests must be independent of each other.
• Speed: Unit tests must run very fast.
• Readable: Test name should clearly say what it tests.
• Deterministic: Same result with same input always.

🔄 Workflow

Source: Spotify's Testing Pyramid & Playwright Best Practices

Phase 1: Strategy & Test Plan

• [ ] Define Coverage Scope: Determine critical user flows and logic requiring testing.
• [ ] Choose Level: Select correct test level according to testing pyramid (Unit -> Integration -> E2E).
• [ ] Infrastructure Setup: Configure Vitest/Jest or Playwright environment, prepare necessary mocks.

Phase 2: Implementation & Interaction

• [ ] Unit Tests: Test functions and UI components in isolation (using Stub/Mock).
• [ ] Integration Flows: Verify compatibility of services and database/API layer.
• [ ] E2E Scenarios: Simulate full flows like "Login -> Checkout" on real browser with Playwright.

Phase 3: Verification & CI/CD

• [ ] Coverage Audit: Analyze test coverage (Line/Branch coverage) and fill gaps.
• [ ] Visual Regressions: Capture unexpected interface changes with "Snapshot Testing".
• [ ] Automated Pipeline: Ensure all tests run in CI/CD stage (before Check-in).

Checkpoints

Testing v2.5 - With Workflow