With LWC Jest, how to mock custom components

Question

I'm trying to unit test my LWC which has another custom component as child. I tried to use the steps describe in this post :

import { createElement } from 'lwc';
import EfxProjectReport from 'c/efxProjectReport';



describe('c-efx-project-report', () => {
    jest.mock(
        './mocks/tsrWhen',
        () => {
            return {
                default: jest.fn()
            };
        },
        { virtual: true }
    );

    afterEach(() => {
        // The jsdom instance is shared across test cases in a single file so reset the DOM
        while (document.body.firstChild) {
            document.body.removeChild(document.body.firstChild);
        }
    });

    it('TODO: test case generated by CLI command, please fill in test logic', () => {
        const element = createElement('c-efx-project-report', {
            is: EfxProjectReport
        });
        document.body.appendChild(element);
        expect(1).toBe(2);
    });
});

With the following directory layout :

efxProjectReport
+ __tests__
++ efxProjectReport.test.js
++ mocks
+++ tsrWhen
++++ tsrWhen.html
++++ tsrWhen.js
+ efxProjectReport.css
+ efxProjectReport.html
+ efxProjectReport.js
+ efxProjectReportConfig.js

And I still get the following error when running my tests ::

Cannot find module 'c/tsrWhen' from 'efxProjectReport.html'

Any clue on how to proceed to mock custom child components ?