[TIPS] Python/Playwright Tricks

Playwright is a powerful tool for automating and testing web applications, offering cross-browser support and high-speed execution. When using Playwright with Python, there are several tricks and best practices you can leverage to enhance your testing efficiency and effectiveness.

1. Leverage Locators

Utilize Playwright's locator feature to interact with page elements instead of relying on XPath or CSS selectors. Locators provide a more reliable and efficient way to find elements, adapting to UI changes more gracefully.

from playwright.sync_api import sync_playwright

with sync_playwright() as p: browser = p.chromium.launch() page = browser.new_page() page.goto('https://example.com') locator = page.locator('text="Example Domain"') assert locator.count() == 1 browser.close()

2. Use Web-First Assertions

Adopt web-first assertions to ensure that tests wait for the necessary conditions before proceeding, reducing flaky test results. Playwright offers built-in assertions like to_be_visible and to_have_text.

page.goto('https://example.com')

page.locator('h1').wait_for(state='visible')

assert page.locator('h1').text_content() == 'Example Domain'

3. Embrace Parallelism and Sharding

Maximize test execution speed by running tests in parallel and utilizing sharding. Playwright supports running tests across multiple workers, which can significantly reduce testing time.

pytest -n auto --dist=loadscope

4. Implement Visual Regression Testing

Visual regression testing helps identify unintended UI changes. Use Playwright’s toHaveScreenshot method to capture and compare screenshots.

page.goto('https://example.com')

page.screenshot(path='screenshot.png')

5. Debugging and Test Insights

Utilize pytest-playwright for enhanced debugging capabilities in your tests. You can run tests in "headed" mode to observe the browser actions visually. Use the --headed option to see the browser as tests execute:

pytest --headed

For deeper insights, utilize the Playwright Inspector with page.pause(), allowing you to step through actions interactively and inspect elements directly:

def test_example(page):

    page.goto('https://example.com')

    page.pause()  # Opens the Playwright Inspector for debugging

    assert page.title() == 'Example Domain

This approach helps you better understand test behavior and quickly identify issues during development. Let me know if there's anything else you'd like to adjust!

6. Mock API Calls

Speed up tests by mocking API calls and focusing only on essential requests. This can help reduce test flakiness and improve execution speed.

page.route('**/api/**', lambda route, request: route.fulfill(body='{"mock": "data"}'))

7. Handle Multiple Contexts and Windows

Test applications that require multiple browser contexts or windows within a single test, simulating scenarios like chat applications.

context1 = browser.new_context()

context2 = browser.new_context()

page1 = context1.new_page()

page2 = context2.new_page()

8. Advanced Configuration Overrides

For specific test cases, override Playwright's default configurations to suit your testing needs, such as altering timeout settings or browser launch options.

playwright = sync_playwright().start()

browser = playwright.chromium.launch(headless=False, slowMo=50)

9. Emulate Devices and Network Conditions

Simulate different device configurations and network conditions to test responsiveness and performance under varied circumstances.

page.emulate_network_conditions(offline=True)

page.goto('https://example.com', timeout=60000)  # Longer timeout for slower networks

By adopting these tricks and best practices, you can harness the full potential of Playwright in your Python projects, achieving more robust and efficient testing workflows.