It is a Jest-ism that shouldn't be in our open source package.
People using Jest can implement a similar pattern directly.
const doc = document.implementation.createHTMLDocument('');
  doc.open();
  doc.write(
    markup ||
      '<!doctype html><html><meta charset=utf-8><title>test doc</title>',
  );
  doc.close();
  return doc;
}
describe('ReactTestUtils', () => {
  beforeEach(() => {
    createRenderer = require('react-test-renderer/shallow').createRenderer;
    React = require('react');
    ReactDOM = require('react-dom');
    ReactDOMServer = require('react-dom/server');
    ReactTestUtils = require('react-dom/test-utils');
  });
  it('Simulate should have locally attached media events', () => {
    expect(Object.keys(ReactTestUtils.Simulate).sort()).toMatchSnapshot();
  });
  it('SimulateNative should have locally attached media events', () => {
    expect(Object.keys(ReactTestUtils.SimulateNative).sort()).toMatchSnapshot();
  });
  it('gives Jest mocks a passthrough implementation with mockComponent()', () => {
    class MockedComponent extends React.Component {