test-architecture

Test Architecture — Advanced Testing Patterns

Use this skill for advanced testing beyond unit tests. Covers E2E, load testing, mutation testing, contract testing, and visual regression. Complements tdd-with-agents (which covers unit tests).

Relationship with tdd-with-agents

1. E2E Testing (Playwright)

Setup

# tests/e2e/conftest.py
import pytest
from playwright.async_api import async_playwright

@pytest.fixture
async def browser():
    async with async_playwright() as p:
        browser = await p.chromium.launch(headless=True)
        yield browser
        await browser.close()

@pytest.fixture
async def page(browser):
    context = await browser.new_context()
    page = await context.new_page()
    yield page
    await context.close()

Test Pattern

# tests/e2e/test_user_flow.py
import pytest

@pytest.mark.asyncio
async def test_user_login_flow(page):
    """E2E: User can log in and see dashboard."""
    await page.goto("http://localhost:8000/login")
    await page.fill('input[name="email"]', "[email protected]")
    await page.fill('input[name="password"]', "password123")
    await page.click('button[type="submit"]')
    
    # Verify redirect to dashboard
    await page.wait_for_url("**/dashboard")
    assert await page.title() == "Dashboard"
    
    # Verify user info displayed
    await page.wait_for_selector(".user-name")
    user_name = await page.text_content(".user-name")
    assert "Test User" in user_name

Running E2E Tests

# Start app first
uvicorn app.main:app --reload &

# Run E2E tests
pytest tests/e2e/ -v --asyncio-mode=auto

2. Load Testing (k6)

k6 Script

// tests/load/api_load_test.js
import http from 'k6/http';
import { check, sleep } from 'k6';

export const options = {
  stages: [
    { duration: '30s', target: 20 },   // Ramp up to 20 users
    { duration: '1m', target: 20 },    // Stay at 20 users
    { duration: '30s', target: 50 },   // Spike to 50 users
    { duration: '1m', target: 50 },    // Stay at 50 users
    { duration: '30s', target: 0 },    // Ramp down
  ],
  thresholds: {
    http_req_duration: ['p(95)<500'],  // 95% of requests < 500ms
    http_req_failed: ['rate<0.01'],    // Error rate < 1%
  },
};

export default function () {
  const res = http.get('http://localhost:8000/api/products');
  check(res, {
    'status is 200': (r) => r.status === 200,
    'response time < 500ms': (r) => r.timings.duration < 500,
  });
  sleep(1);
}