Import function from a Jest manual mock with Typescript

Question

I\'m creating a custom mock (of an ES6 class) with Jest in a Typescript project. The mock creates end exports a few mock.fn() so that they could be spied on in

Answer 1

I have the same problem and I only have a workaround. My problem is that I manually mock fs from node.

So I have a manual mock for 'fs' which looks roughly like this:

const fs = jest.genMockFromModule("fs");

let mockFiles = {};

function __clearMocks(){
    mockFiles = {};
}

module.exports = fs;

So clearly when my test case imports fs it would not work:

import * as fs from 'fs';
fs.__clearMocks();

To get this working I create an extension of the type:

declare module 'fs' {
    export function __clearMocks(): void; 
}

So now I can modify my testcase like this:

import * as fs from 'fs';
import 'fsExtension';
fs.__clearMocks();

Hopefully this helps you!