Playwright Python 教程：高级篇

目标

本篇将带你探索 Playwright 的高级功能，让你能够构建更加专业、强大和高效的自动化测试解决方案。我们将涵盖网络拦截、认证持久化、高级配置、视频录制以及与测试框架的集成。

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一、网络拦截与模拟（Network Interception & Mocking）

Playwright 允许你拦截和修改网络请求，这对于模拟 API 响应、测试错误处理或减少对外部服务的依赖非常有用。

1. 基本请求/响应拦截

from playwright.sync_api import sync_playwrightdef test_api_interception():with sync_playwright() as p:browser = p.chromium.launch(headless=False)page = browser.new_page()# 启用请求拦截page.route("**/api/users", lambda route: route.fulfill(status=200,content_type="application/json",body='{"id": 123, "name": "Mock User"}'))page.goto("https://example.com/user-profile")# 此时页面对 /api/users 的请求将返回我们模拟的数据page.click("#refresh-user")browser.close()

2. 根据条件修改响应

def test_conditional_interception():with sync_playwright() as p:browser = p.chromium.launch(headless=False)page = browser.new_page()def handle_route(route):if "api/items" in route.request.url:# 修改响应route.fulfill(status=200,body='[{"id": 1, "name": "Mock Item"}]')else:# 继续正常请求route.continue_()# 注册路由处理程序page.route("**/*", handle_route)page.goto("https://example.com/items")browser.close()

3. 模拟网络错误

def test_network_failure():with sync_playwright() as p:browser = p.chromium.launch(headless=False)page = browser.new_page()# 模拟网络错误page.route("**/api/data", lambda route: route.abort())page.goto("https://example.com/data-page")# 验证错误处理assert page.is_visible("text=Failed to load data")browser.close()

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二、认证与持久化状态

1. 保存和恢复认证状态

import os
from playwright.sync_api import sync_playwrightdef test_auth_persistence():with sync_playwright() as p:browser = p.chromium.launch(headless=False)context = browser.new_context()page = context.new_page()# 执行登录操作page.goto("https://example.com/login")page.fill("#username", "testuser")page.fill("#password", "testpass")page.click("#login-btn")# 等待登录完成page.wait_for_url("**/dashboard")# 保存认证状态到文件context.storage_state(path="auth_state.json")browser.close()def test_using_saved_auth():with sync_playwright() as p:browser = p.chromium.launch(headless=False)# 使用保存的认证状态创建上下文context = browser.new_context(storage_state="auth_state.json")page = context.new_page()# 直接访问需要认证的页面page.goto("https://example.com/dashboard")# 验证已登录状态assert page.is_visible("text=Welcome, testuser")browser.close()

2. 多用户场景测试

def test_multiple_users():with sync_playwright() as p:browser = p.chromium.launch(headless=False)# 创建两个独立的上下文（模拟两个用户）user1_context = browser.new_context()user1_page = user1_context.new_page()user2_context = browser.new_context()user2_page = user2_context.new_page()# 用户1登录user1_page.goto("https://example.com/login")user1_page.fill("#username", "user1")user1_page.fill("#password", "pass1")user1_page.click("#login-btn")user1_page.wait_for_url("**/dashboard")# 用户2登录user2_page.goto("https://example.com/login")user2_page.fill("#username", "user2")user2_page.fill("#password", "pass2")user2_page.click("#login-btn")user2_page.wait_for_url("**/dashboard")# 验证两个用户独立会话assert user1_page.is_visible("text=Welcome, user1")assert user2_page.is_visible("text=Welcome, user2")browser.close()

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三、高级浏览器配置

1. 模拟设备和地理位置

def test_device_simulation():with sync_playwright() as p:# 使用预定义的设备配置（如 iPhone 11）iPhone_11 = p.devices["iPhone 11"]browser = p.chromium.launch(headless=False)# 创建带有设备模拟的上下文context = browser.new_context(**iPhone_11)page = context.new_page()page.goto("https://example.com")# 验证移动视图assert page.viewport_size["width"] == 414  # iPhone 11 宽度browser.close()def test_geolocation():with sync_playwright() as p:browser = p.chromium.launch(headless=False)# 设置地理位置和权限context = browser.new_context(geolocation={"longitude": 116.397128, "latitude": 39.916527},  # 北京permissions=["geolocation"])page = context.new_page()page.goto("https://maps.example.com")# 触发地理位置请求page.click("#get-location")# 验证位置相关功能assert page.is_visible("text=Beijing")browser.close()

2. 代理设置

def test_with_proxy():with sync_playwright() as p:browser = p.chromium.launch(headless=False,proxy={"server": "http://myproxy.com:8080","username": "user","password": "pass"})context = browser.new_context()page = context.new_page()page.goto("https://example.com")# 验证页面加载成功assert page.title() == "Example Domain"browser.close()

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四、录制视频与追踪

1. 录制测试视频

def test_with_video_recording():with sync_playwright() as p:browser = p.chromium.launch(headless=False)# 启用视频录制context = browser.new_context(record_video_dir="videos/")page = context.new_page()# 执行测试操作page.goto("https://example.com")page.click("a")page.wait_for_timeout(1000)# 关闭上下文会自动保存视频context.close()browser.close()

2. 使用追踪记录

def test_with_tracing():with sync_playwright() as p:browser = p.chromium.launch(headless=False)context = browser.new_context()# 开始追踪context.tracing.start(screenshots=True, snapshots=True)page = context.new_page()page.goto("https://example.com")page.click("a")# 停止追踪并保存context.tracing.stop(path="trace.zip")browser.close()# 查看追踪记录
# 使用命令: playwright show-trace trace.zip

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五、与 Pytest 集成

1. 基本 Pytest 集成

# test_example.py
import pytest
from playwright.sync_api import Page, expectdef test_example_page(page: Page):page.goto("https://example.com")expect(page).to_have_title("Example Domain")def test_login(page: Page):page.goto("https://example.com/login")page.fill("#username", "testuser")page.fill("#password", "testpass")page.click("#login-btn")expect(page).to_have_url("**/dashboard")

2. 使用 Pytest Fixtures

# conftest.py
import pytest
from playwright.sync_api import Playwright, Browser, [e-mail](scope="session")
def browser(playwright: Playwright):# 启动浏览器（会话级别，所有测试共享）browser = playwright.chromium.launch(headless=False)yield browserbrowser.close()@pytest.fixture
def context(browser: Browser):# 为每个测试创建新的上下文context = browser.new_context()yield contextcontext.close()@pytest.fixture
def page(context: BrowserContext):# 为每个测试创建新的页面page = context.new_page()yield pagepage.close()# test_with_fixtures.py
def test_with_fixtures(page):page.goto("https://example.com")assert page.title() == "Example Domain"

3. 参数化测试

import [e-mail]("username,password,expected", [("correct", "correct", True),("wrong", "correct", False),("correct", "wrong", False),
])
def test_login_combinations(page, username, password, expected):page.goto("https://example.com/login")page.fill("#username", username)page.fill("#password", password)page.click("#login-btn")if expected:expect(page).to_have_url("**/dashboard")else:expect(page).to_have_url("**/login")expect(page).to_have_text("Invalid credentials")

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六、实战：完整的端到端测试示例

import pytest
from playwright.sync_api import Page, expectdef test_complete_ecommerce_flow(page: Page):# 1. 浏览产品page.goto("https://demo-shop.example.com")expect(page).to_have_title("Demo Shop")# 2. 搜索产品page.fill("#search-input", "laptop")page.click("#search-button")expect(page).to_have_url("**/search?q=laptop")# 3. 查看产品详情page.click(".product-item:first-child")expect(page).to_have_url("**/product/")# 4. 添加到购物车page.click("#add-to-cart")expect(page.locator("#cart-count")).to_have_text("1")# 5. 查看购物车page.click("#view-cart")expect(page).to_have_url("**/cart")# 6. 结账page.click("#checkout")expect(page).to_have_url("**/checkout")# 7. 填写配送信息page.fill("#name", "John Doe")page.fill("#address", "123 Main St")page.fill("#city", "Anytown")page.select_option("#country", "US")page.click("#continue-to-payment")# 8. 填写支付信息（使用模拟）page.route("**/api/payment", lambda route: route.fulfill(status=200,body='{"success": true, "transactionId": "12345"}'))page.fill("#card-number", "4242424242424242")page.fill("#expiry", "12/25")page.fill("#cvv", "123")page.click("#complete-purchase")# 9. 验证订单确认expect(page).to_have_url("**/order-confirmation")expect(page).to_have_text("Thank you for your order!")

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高级篇总结

通过本篇学习，你已经掌握了 Playwright 的高级功能：

1. 网络拦截与模拟：能够拦截和修改网络请求，实现 API 模拟和错误测试。
2. 认证持久化：保存和恢复登录状态，提高测试效率。
3. 高级浏览器配置：模拟设备、地理位置和代理设置。
4. 录制与追踪：录制测试视频和使用追踪功能进行调试。
5. Pytest 集成：使用行业标准测试框架组织测试用例。

这些高级技能将使你能够构建更加专业、可靠和高效的自动化测试解决方案。

最佳实践建议

1. 保持测试独立：每个测试应该能够独立运行，不依赖其他测试的状态。
2. 使用页面对象模式：将页面元素和操作封装成类，提高代码可维护性。
3. 合理使用等待：优先使用 Playwright 的自动等待和显式等待，避免固定等待。
4. 定期维护选择器：随着前端代码变化，定期更新和维护元素选择器。
5. 并行执行测试：利用 Playwright 的并行执行能力加快测试速度。