@covers PHPUnit_Framework_Assert::assertTag
public function testAssertDescendantContentAttributes() {
  $matcher = array(
    'id' => 'test_id',
    'content' => 'Test Id Text',
    'attributes' => array(
      'id' => 'test_id',
    ),
    'descendant' => array(
      'tag' => 'span',
      'attributes' => array(
        'id' => 'test_subchild_id',
      ),
    ),
  );
  $this
    ->assertTag($matcher, $this->html);
}