Jest - mock function, that is imported from another file

Question

The tested file uses a function that is imported from another file

import {myFunc} from './myFile'

How can I mock return value for this function in my tests for this file? I'm using jest.

Possible duplicate of [How can I mock an ES6 module import using Jest?](https://stackoverflow.com/questions/40465047/how-can-i-mock-an-es6-module-import-using-jest) — Agney, Apr 30 '19 at 12:48

score 9 · Accepted Answer · answered Apr 30 '19 at 13:18

9

This is what worked for me, I'm not sure if it's a good practice tho:

 import * as myFile from "./myFile";
 jest.mock("./myFile");
 myFile.myFunc = jest.fn().mockImplementation(() => {
     return "Some Value";
 });

answered Apr 30 '19 at 13:18

Anna

7

`jest.spyOn(myFile, 'myFunc').mockReturnValue('Some Value');` looks a bit nicer – Alejandro Oct 21 '20 at 17:17
Cannot do that with a `const`. – Vitaly Zdanevich Nov 23 '22 at 18:17

1 Answers1