Assert that an element contains a descendant element matching the given selector.

var element = createElement(`
  <section>
    <h1>Numbers</h1>
    <hr>
    <ol data-test-id="numbers">
      <li>One</li>
      <li>Two</li>
      <li>Three</li>
    </ol>
  </section>
`);
 
expect(element, 'to contain elements matching', '[data-test-id=numbers]');

You get the following error when it fails:

expect(element, 'to contain elements matching', '[data-test-id=emojies]');

expected
<section>
  
<h1>Numbers</h1>
  
<hr>
  
<ol data-test-id="numbers">
  
<li>One</li>
  
<li>Two</li>
  
<li>Three</li>
</ol>
</section>
to contain elements matching '[data-test-id=emojies]'

Using the not flag, you can assert that the selector can't matching any descendant elements:

expect(element, 'not to contain elements matching', '[data-test-id=emojies]');

You get the following error when it fails:

expect(element, 'not to contain elements matching', 'li');

expected
<section>
  
<h1>Numbers</h1>
  
<hr>
  
<ol data-test-id="numbers">
  
<li>...</li>
  
<li>...</li>
  
<li>...</li>
</ol>
</section>
not to contain elements matching 'li'
 
NodeList[
  
<li>One</li>, // should be removed
<li>Two</li>, // should be removed
<li>Three</li> // should be removed
]