title: react-testing-library why use test id
body: <p>I am using react-testing-library. In the document it says</p>
  
  <blockquote>
    <p>Note that using this as an escape hatch to query by class or id is a
    bad practice because users can't see or identify these attributes. Use
    a testid if you have to.</p>
  </blockquote>
  
  <p>I was wondering why this is a bad practice. I do not want to litter my code with data-testid. I already have ids and classNames in my component. Why is it not recommended to use them?</p>
  
  <p>Thanks.</p>