title: React Testing Library getByLabelText doesn't concat multipart aria-labelledby
body: <p>Along the lines of <a href="https://developer.mozilla.org/en-US/docs/Web/Accessibility/ARIA/forms/Multipart_labels" rel="nofollow noreferrer">this MDN article</a>, I have a checkbox input labelled by a combination of three different elements: a label, a text field, and then another label. </p>
  
  <p>So the checkbox input has an <code>aria-labelledby</code> attribute with a value like <code>label1 text-field label2</code>.</p>
  
  <pre class="lang-html prettyprint-override"><code>&lt;input type="checkbox" aria-labelledby="allow-up-to num words-in-between" /&gt;
  &lt;div&gt;
    &lt;label id="allow-up-to"&gt;allow up to&lt;/label&gt;
    &lt;input id="num" type="text" value="0" /&gt;
    &lt;label id="words-in-between"&gt;words in between&lt;/label&gt;
  &lt;/div&gt;
  </code></pre>
  
  <p>In my test, I'm trying to grab the checkbox based on that label. </p>
  
  <p>I can successfully grab the input with <code>getByLabelText('text of label1')</code> or <code>getByLabelText('text of label2')</code>, but giving it the full, concatenated label <code>getByLabelText('text of label1 value of text-field text of label2')</code> results in nothing being found. </p>
  
  <pre class="lang-js prettyprint-override"><code>getByLabelText("allow up to"); // works
  getByLabelText("words in between") // works
  getByLabelText("allow up to 0 words in between") // does not work
  </code></pre>
  
  <p>Trying <code>getByLabelText('value of text-field')</code> doesn't work either, but even if I remove the text field from <code>aria-labelledby</code>, I still can't get the input using <code>getByLabelText('text of label1 text of label2')</code>. <a href="https://codesandbox.io/s/rtl-aria-labelledby-multipart-vpjpx?from-embed=&amp;file=/src/__tests__/index.js" rel="nofollow noreferrer">Here's a  codesandbox</a> with a simplified version of the actual UI I'm trying to test.</p>
  
  <p>Is <code>getByLabelText</code> supposed to work this way (even though according to the MDN article multiple labels in an <code>aria-labelledby</code> should be concatenated by a screen reader)? If so, is there another way I can grab the input by the full label text?</p>