Retry-ability

浏览器中的测试由于其异步特性，可能会不一致地失败。因此，即使条件延迟（如超时、网络请求或动画），也必须有办法保证断言成功。为此，Vitest 通过 expect.poll和 expect.element API 提供了可重试的断言：

import { expect, test } from 'vitest'
import { screen } from '@testing-library/dom'

test('error banner is rendered', async () => {
  triggerError()

  // @testing-library provides queries with built-in retry-ability
  // It will try to find the banner until it's rendered
  const banner = await screen.findByRole('alert', {
    name: /error/i,
  })

  // Vitest provides `expect.element` with built-in retry-ability
  // It will check `element.textContent` until it's equal to "Error!"
  await expect.element(banner).toHaveTextContent('Error!')
})

TIP

expect.element 是 expect.poll(() => element)的简写，工作方式完全相同。

toHaveTextContent 和所有其他 @testing-library/jest-dom断言在没有内置重试机制的常规expect中仍然可用：

// will fail immediately if .textContent is not `'Error!'`
expect(banner).toHaveTextContent('Error!')

Retry-ability ​

Retry-ability