# vitest/prefer-called-once

📝 Enforce using `toBeCalledOnce()` or `toHaveBeenCalledOnce()`.

🚫 This rule is _disabled_ in the 🌐 `all` config.

🔧 This rule is automatically fixable by the [`--fix` CLI option](https://eslint.org/docs/latest/user-guide/command-line-interface#--fix).

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## Rule Details

This rule aims to enforce the use of `toBeCalledOnce()` or `toHaveBeenCalledOnce()` over `toBeCalledTimes(1)` or `toHaveBeenCalledTimes(1)`.

Examples of **incorrect** code for this rule:

```ts
test('foo', () => {
  const mock = vi.fn()
  mock('foo')
  expect(mock).toBeCalledTimes(1)
  expect(mock).toHaveBeenCalledTimes(1)
})
```

Examples of **correct** code for this rule:

```ts
test('foo', () => {
  const mock = vi.fn()
  mock('foo')
  expect(mock).toBeCalledOnce()
  expect(mock).toHaveBeenCalledOnce()
})
```