It is a Jest-ism that shouldn't be in our open source package.
People using Jest can implement a similar pattern directly.
['x', 'a'],
    );
    expect(scryResults4.length).toBe(0);
    const scryResults5 = ReactTestUtils.scryRenderedDOMComponentsWithClass(
      renderedComponent,
      ['x a'],
    );
    expect(scryResults5.length).toBe(0);
  });
  it('traverses children in the correct order', () => {
    class Wrapper extends React.Component {
      render() {
        return <div>{this.props.children}</div>;
      }
    }
    const container = document.createElement('div');
    ReactDOM.render(
      <Wrapper>
        {null}
        <div>purple</div>
      </Wrapper>,
      container,
    );
    const tree = ReactDOM.render(
      <Wrapper>
        <div>orange</div>
        <div>purple</div>
      </Wrapper>,
      container,
    );