---
{
.title = "Jest mocks are ...different",
.date = @date("2022-04-25T00:00:00"),
.author = "koehr",
.draft = false,
.layout = "til.html",
.description = "",
.tags = [],
}
---
If you want to mock an imported function in Jest in a way that allows you to check if it has been called, you can not do the seemingly straighforward:

```js
// mock prefix necessary btw
const mockThatFunction = jest.fn(() => 'stuff')

jest.mock('@/path/to/module', () => ({
  thatFunction: mockThatFunction,
}))

// ...in test descriptions
expect(mockThatFunction).toHaveBeenCalled()
```

This way thatFunction will be undefined without anyone telling you why.

What you need to do instead:

```js
import { thatFunction } from '@/path/to/module'

jest.mock('@/path/to/module', () => ({
  thatFunction: jest.fn(() => 'stuff'),
}))

// ...in test descriptions
expect(thatFunction).toHaveBeenCalled()
```