mirror of
https://github.com/vitest-dev/vitest.git
synced 2025-12-08 18:26:03 +00:00
38 lines
1.4 KiB
Markdown
38 lines
1.4 KiB
Markdown
---
|
|
title: Retry-ability | Browser Mode
|
|
---
|
|
|
|
# Retry-ability
|
|
|
|
Tests in the browser might fail inconsistently due to their asynchronous nature. Because of this, it is important to have a way to guarantee that assertions succeed even if the condition is delayed (by a timeout, network request, or animation, for example). For this purpose, Vitest provides retriable assertions out of the box via the [`expect.poll`](/api/expect#poll) and `expect.element` APIs:
|
|
|
|
```ts
|
|
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` is a shorthand for `expect.poll(() => element)` and works in exactly the same way.
|
|
|
|
`toHaveTextContent` and all other [`@testing-library/jest-dom`](https://github.com/testing-library/jest-dom) assertions are still available on a regular `expect` without a built-in retry-ability mechanism:
|
|
|
|
```ts
|
|
// will fail immediately if .textContent is not `'Error!'`
|
|
expect(banner).toHaveTextContent('Error!')
|
|
```
|
|
:::
|