GroupButton.jsx

import React from 'react';
import Button from './Button'

const GroupButton = ({ children}) => (
  <div className='btn-group'>
    {children}  
  </div>
);

ReactDOM.render(
  <GroupButton>
    <Button>Left</Button>
    <Button>Middle</Button>
    <Button>Right</Button>
  </GroupButton>
  ,
  document.getElementById('root')
);