Module 6 · Python for SDETs
UI automation
with Playwright
Drive a real browser — locate, act, and assert like a user would
page fixture
get_by_* locators
auto-waiting
web-first expect
One fixture: page
# pip install pytest-playwright
import re
from playwright.sync_api import expect
def test_products_page(page):
page.goto("http://localhost:3000/products")
expect(page).to_have_title(re.compile("TestMarket Lab"))
🌐pytest-playwright hands every test a fresh page — a clean browser context, no setup or teardown to write.
🎬Headless by default; add --headed to watch it drive, --slowmo to slow it down while debugging.
Find elements the way a user sees them
Locators: get_by_*
test id
get_by_test_id()
the data-testid hooks the app ships — most robust
role
get_by_role()
buttons, links, headings — also an a11y check
label
get_by_label()
form fields by their visible label
text
get_by_text()
visible text — handy, but the most fragile
🎯Locate by intent: get_by_test_id is the most robust (a hook that survives restyling); get_by_role / get_by_label double as accessibility checks; get_by_text is the most fragile.
No manual sleeps
Actions wait for the element — automatically
locate the element
→
Playwright waits: visible & enabled
→
then .click() / .fill()
page.get_by_label("Email").fill("customer@test.io")
page.get_by_test_id("login-submit").click()
⏱️Each action auto-waits up to the timeout for the element to be actionable — so time.sleep() is a smell, not a fix.
Assertions that retry
from playwright.sync_api import expect
# waits until it's visible, or fails
expect(
page.get_by_test_id("nav-logout")
).to_be_visible()
✅expect(locator) auto-retries until the condition holds or the timeout hits — no flake from asserting a millisecond too early.
🆚Different from pytest's plain assert: a web-first expect polls the live page instead of checking once.
🎭
Drive the
real browser
Locate by role, act with auto-waiting, and assert with web-first expect
🧪
Practice
Log in through the UI and expect the logout button visible
🎯
Locators
Reach for get_by_role / get_by_label before CSS or XPath
➡️
Module 7
Page Object Model — hide selectors behind readable page classes