How to mock out sub-components when unit testing a React component with Jest

I have a React component that I am trying to write some tests around. I have broken it down to the simplest test possible.

jest.dontMock('../Overlay.react.js');

import React from 'react';
import ReactDOM from 'react-dom';

var Overlay = require('../Overlay.react.js'); // this is the culprit!

describe('Overlay', () => {
    it('should work', () => {
        expect(true).toEqual(true);
    });
});

When requiring the component I am trying to test, it seems to not be mocking its subcomponents. At the top of Overlay.react.js, I have the following import: import LoadingSpinner from 'loadingIndicator/LoadingIndicatorSpin.react'; When running my test, I get the following error:

• SyntaxError: /Users/dev/work/react-prototype/src/components/root/routes/components/subset1/components/Overlay.react.js: /Users/dev/work/react-prototype/src/components/root/routes/components/loadingIndicator/LoadingIndicatorSpin.react.js: /Users/dev/work/react-prototype/src/components/root/routes/components/loadingIndicator/sass/style.sass: Unexpected token ILLEGAL

It seems like instead of mocking the components, it is going right down to the sub-component's sass file and throwing a fit. My understanding was that Jest mocks everything except for what you tell it to not mock.

What is the right way to formulate these tests so that sub-components do not cause jest to explode when being imported during a test?