A browser test that asserted a redirect, not a page

A test that filled a form, submitted it and asserted on the resulting page, which passed when the redirect went somewhere wrong.

// what it did
await page.click('button[type=submit]')
await expect(page.locator('.order-reference')).toBeVisible()

// which passed after a redirect to the WRONG order,
// because both pages have that element.

// what it does
await page.click('button[type=submit]')
await expect(page).toHaveURL(//orders/8814/confirmation$/)
await expect(page.locator('.order-reference')).toHaveText('ORD-8814')

Asserting on a page’s content without asserting where you are is the browser-test equivalent of asserting a method did not throw. The URL assertion is one line and it is the one that distinguishes “something rendered” from “the right thing rendered”, which is what the test was for.