Playwright Python Assertions: Expect, Soft Assertions, Timeouts

A test is only as good as its checks. Playwright for Python ships a dedicated assertion library, expect, built for web pages that change over time: every expect check keeps retrying until the page reaches the expected state or a timeout runs out. In this lesson you will use every important assertion on the SQA Tools practice page, see why a plain assert can be flaky on a dynamic page, and learn negation, custom messages, timeouts and soft assertions.

📖 What You’ll Learn: what web-first assertions are and how they retry, page assertions (to_have_title, to_have_url), visibility and state assertions, text assertions (exact, partial, regex, lists, ignore_case), value, attribute, class, CSS, id and count assertions, accessibility assertions, API response assertions, not_ negation, custom failure messages, per-assertion and global timeouts, soft assertions with expect.soft, and when a plain assert is the right tool.

🎯 What Is a Web-First Assertion?

An assertion checks that the application is in the state you expect. If the check fails, the test fails.

Python already has the assert statement, and pytest makes it powerful (you used it in Module 3). So why does Playwright add its own expect function?

Because web pages change after your action. Click “Load Success” on the practice page, and the text below the button shows “Loading…” first. It changes to “Data loaded successfully!” 3 seconds later. A check that reads the text once, right after the click, sees the wrong text and fails, even though the page works perfectly.

expect() solves this. It retries the check again and again until it passes or the timeout runs out (5 seconds by default). That is what “web-first” means: the assertion waits for the page, like a human tester would.

from playwright.sync_api import expect

expect(page.locator("#loader")).to_have_text("Data loaded successfully!")

expect(...) takes a Locator, a Page or an APIResponse.
It returns an assertions object with methods such as to_have_text(), to_be_visible() and to_have_url().
Each method retries until it passes, or raises AssertionError after the timeout.

All examples below run against the SQA Tools practice page. Every test receives the opened page from this fixture:

📄 tests/conftest.py

import pytest
from playwright.sync_api import Page


@pytest.fixture
def practice(page: Page) -> Page:
    page.goto("https://sqatools.in/automation-practice-page/")
    return page

📄 Page Assertions: Title and URL

📄 tests/test_page_assertions.py

import re

from playwright.sync_api import Page, expect


def test_title_and_url(practice: Page):
    # Exact title
    expect(practice).to_have_title("Automation Practice Page - SQA Tools")

    # Part of the title, with a regular expression
    expect(practice).to_have_title(re.compile("Practice Page"))

    # Exact URL, then a URL pattern
    expect(practice).to_have_url("https://sqatools.in/automation-practice-page/")
    expect(practice).to_have_url(re.compile(r"/automation-practice-page/$"))

Pass the page itself (not a locator) to expect() for page-level checks.
A plain string must match exactly. Use re.compile(...) when only part of the value matters, for example a URL that contains an id or a query string.
to_have_url() is the right check after a click that navigates: it waits for the new URL instead of reading page.url too early.