loulanyue 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)
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
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
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
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
npx playwright test tests/search.spec.ts --repeat-each=10
npx playwright test tests/search.spec.ts --retries=3
Common Causes & Fixes
Race conditions:
// Bad: assumes element is ready
await page.click('[data-testid="button"]')
// Good: auto-wait locator
await page.locator('[data-testid="button"]').click()
Network timing:
// Bad: arbitrary timeout
await page.waitForTimeout(5000)
// Good: wait for specific condition
await page.waitForResponse(resp => resp.url().includes('/api/data'))
Animation timing:
// 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
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
await browser.startTracing(page, {
path: 'artifacts/trace.json',
screenshots: true,
snapshots: true,
})
// ... test actions ...
await browser.stopTracing()
Video
// In playwright.config.ts
use: {
video: 'retain-on-failure',
videosPath: 'artifacts/videos/'
}
CI/CD Integration
# .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
# 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
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
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()
})