e2e-testing

# E2E Testing Patterns Comprehensive Playwright patterns for building stable, fast, and maintainable E2E test suites. ## Test File Organization ``` tests/ ├── e2e/ │ ├── auth/ │ │ ├── login.spec.ts │ │ ├── logout.spec.ts │ │ └── register.spec.ts │ ├── features/ │ │ ├── browse.spec.ts │ │ ├── search.spec.ts │ │ └── create.spec.ts │ └── api/ │ └── endpoints.spec.ts ├── fixtures/ │ ├── auth.ts │ └── data.ts └── playwright.config.ts ``` ## Page Object Model (POM) ```typescript import { Page, Locator } from '@playwright/test' export class ItemsPage { readonly page: Page readonly searchInput: Locator readonly itemCards: Locator readonly createButton: Locator constructor(page: Page) { this.page = page this.searchInput = page.locator('[data-testid="search-input"]') this.itemCards = page.locator('[data-testid="item-card"]') this.createButton = page.locator('[data-testid="create-btn"]') } async goto() { await this.page.goto('/items') await this.page.waitForLoadState('networkidle') } async search(query: string) { await this.searchInput.fill(query) await this.page.waitForResponse(resp => resp.url().includes('/api/search')) await this.page.waitForLoadState('networkidle') } async getItemCount() { return await this.itemCards.count() } } ``` ## Test Structure ```typescript import { test, expect } from '@playwright/test' import { ItemsPage } from '../../pages/ItemsPage' test.describe('Item Search', () => { let itemsPage: ItemsPage test.beforeEach(async ({ page }) => { itemsPage = new ItemsPage(page) await itemsPage.goto() }) test('should search by keyword', async ({ page }) => { await itemsPage.search('test') const count = await itemsPage.getItemCount() expect(count).toBeGreaterThan(0) await expect(itemsPage.itemCards.first()).toContainText(/test/i) await page.screenshot({ path: 'artifacts/search-results.png' }) }) test('should handle no results', async ({ page }) => { await itemsPage.search('xyznonexistent123') await expect(page.locator('[data-testid="no-results"]')).toBeVisible() expect(await itemsPage.getItemCount()).toBe(0) }) }) ``` ## Playwright Configuration ```typescript import { defineConfig, devices } from '@playwright/test' export default defineConfig({ testDir: './tests/e2e', fullyParallel: true, forbidOnly: !!process.env.CI, retries: process.env.CI ? 2 : 0, workers: process.env.CI ? 1 : undefined, reporter: [ ['html', { outputFolder: 'playwright-report' }], ['junit', { outputFile: 'playwright-results.xml' }], ['json', { outputFile: 'playwright-results.json' }] ], use: { baseURL: process.env.BASE_URL || 'http://localhost:3000', trace: 'on-first-retry', screenshot: 'only-on-failure', video: 'retain-on-failure', actionTimeout: 10000, navigationTimeout: 30000, }, projects: [ { name: 'chromium', use: { ...devices['Desktop Chrome'] } }, { name: 'firefox', use: { ...devices['Desktop Firefox'] } }, { name: 'webkit', use: { ...devices['Desktop Safari'] } }, { name: 'mobile-chrome', use: { ...devices['Pixel 5'] } }, ], webServer: { command: 'npm run dev', url: 'http://localhost:3000', reuseExistingServer: !process.env.CI, timeout: 120000, }, }) ``` ## Flaky Test Patterns ### Quarantine ```typescript test('flaky: complex search', async ({ page }) => { test.fixme(true, 'Flaky - Issue #123') // test code... }) test('conditional skip', async ({ page }) => { test.skip(process.env.CI, 'Flaky in CI - Issue #123') // test code... }) ``` ### Identify Flakiness ```bash npx playwright test tests/search.spec.ts --repeat-each=10 npx playwright test tests/search.spec.ts --retries=3 ``` ### Common Causes & Fixes **Race conditions:** ```typescript // Bad: assumes element is ready await page.click('[data-testid="button"]') // Good: auto-wait locator await page.locator('[data-testid="button"]').click() ``` **Network timing:** ```typescript // Bad: arbitrary timeout await page.waitForTimeout(5000) // Good: wait for specific condition await page.waitForResponse(resp => resp.url().includes('/api/data')) ``` **Animation timing:** ```typescript // Bad: click during animation await page.click('[data-testid="menu-item"]') // Good: wait for stability await page.locator('[data-testid="menu-item"]').waitFor({ state: 'visible' }) await page.waitForLoadState('networkidle') await page.locator('[data-testid="menu-item"]').click() ``` ## Artifact Management ### Screenshots ```typescript await page.screenshot({ path: 'artifacts/after-login.png' }) await page.screenshot({ path: 'artifacts/full-page.png', fullPage: true }) await page.locator('[data-testid="chart"]').screenshot({ path: 'artifacts/chart.png' }) ``` ### Traces ```typescript await browser.startTracing(page, { path: 'artifacts/trace.json', screenshots: true, snapshots: true, }) // ... test actions ... await browser.stopTracing() ``` ### Video ```typescript // In playwright.config.ts use: { video: 'retain-on-failure', videosPath: 'artifacts/videos/' } ``` ## CI/CD Integration ```yaml # .github/workflows/e2e.yml name: E2E Tests on: [push, pull_request] jobs: test: runs-on: ubuntu-latest steps: - uses: actions/checkout@v4 - uses: actions/setup-node@v4 with: node-version: 20 - run: npm ci - run: npx playwright install --with-deps - run: npx playwright test env: BASE_URL: ${{ vars.STAGING_URL }} - uses: actions/upload-artifact@v4 if: always() with: name: playwright-report path: playwright-report/ retention-days: 30 ``` ## Test Report Template ```markdown # E2E Test Report **Date:** YYYY-MM-DD HH:MM **Duration:** Xm Ys **Status:** PASSING / FAILING ## Summary - Total: X | Passed: Y (Z%) | Failed: A | Flaky: B | Skipped: C ## Failed Tests ### test-name **File:** `tests/e2e/feature.spec.ts:45` **Error:** Expected element to be visible **Screenshot:** artifacts/failed.png **Recommended Fix:** [description] ## Artifacts - HTML Report: playwright-report/index.html - Screenshots: artifacts/*.png - Videos: artifacts/videos/*.webm - Traces: artifacts/*.zip ``` ## Wallet / Web3 Testing ```typescript test('wallet connection', async ({ page, context }) => { // Mock wallet provider await context.addInitScript(() => { window.ethereum = { isMetaMask: true, request: async ({ method }) => { if (method === 'eth_requestAccounts') return ['0x1234567890123456789012345678901234567890'] if (method === 'eth_chainId') return '0x1' } } }) await page.goto('/') await page.locator('[data-testid="connect-wallet"]').click() await expect(page.locator('[data-testid="wallet-address"]')).toContainText('0x1234') }) ``` ## Financial / Critical Flow Testing ```typescript test('trade execution', async ({ page }) => { // Skip on production — real money test.skip(process.env.NODE_ENV === 'production', 'Skip on production') await page.goto('/markets/test-market') await page.locator('[data-testid="position-yes"]').click() await page.locator('[data-testid="trade-amount"]').fill('1.0') // Verify preview const preview = page.locator('[data-testid="trade-preview"]') await expect(preview).toContainText('1.0') // Confirm and wait for blockchain await page.locator('[data-testid="confirm-trade"]').click() await page.waitForResponse( resp => resp.url().includes('/api/trade') && resp.status() === 200, { timeout: 30000 } ) await expect(page.locator('[data-testid="trade-success"]')).toBeVisible() }) ```