Assertions and fixtures

Web-first assertions auto-retry until the condition holds (5s default):

• await expect(locator).toBeVisible() / toHaveText('...') / toHaveCount(3)
• await expect(page).toHaveURL(/checkout/)
• Negative: await expect(locator).toBeHidden() — verifies ABSENCE with waiting too

Plain value assertions (no retry): expect(total).toBe(100) — for API responses and calculations.

Fixtures are Playwright's setup/teardown mechanism: the page in test('...', async ({ page, context }) => ...) is itself a fixture. Writing your own: test.extend<{ loggedInPage: Page }>({...}) — setup before await use(...), teardown after. Advantages over beforeEach: composition, typing, lazy instantiation.