title: How to add data-testid attribute to react-select components
body: <p>Using react-testing-library, I wish to test a form implemented in React.</p>
  
  <p>That form includes a React component of type react-select.  </p>
  
  <p>It is necessary to click a part of the react-select component that has no label, no text, etc.  (E.g. the dropdown arrow).</p>
  
  <p>Ordinarily, the react-testing-library way to do this is to add a 'data-testid' attribute to the item in question.</p>
  
  <p>I've found that it's possible to give each part of the react-select a CSS class attribute, by providing the 'classNamePrefix' prop to the react-select component.  Is there some way to do the same for data-testid attribute?</p>
  
  <p>Note: I'm aware I can provide custom implementations of the components of react-select, but that seems like overkill to get one attribute in place.</p>