trait AssertButtonsTrait in Drupal 9

trait AssertButtonsTrait {

  /**
   * Assert method to verify the buttons in the dropdown element.
   *
   * @param array $buttons
   *   A collection of buttons to assert for on the page.
   * @param bool $dropbutton
   *   Whether to check if the buttons are in a dropbutton widget or not.
   */
  public function assertButtons(array $buttons, $dropbutton = TRUE) {

    // Verify that the number of buttons passed as parameters is
    // available in the dropbutton widget.
    if ($dropbutton) {
      $count = count($buttons);

      // Assert there is no save button.
      $this
        ->assertSession()
        ->buttonNotExists('Save');

      // Dropbutton elements.
      $this
        ->assertSession()
        ->elementsCount('xpath', '//div[@class="dropbutton-wrapper"]//input[@type="submit"]', $count);
      for ($i = 1; $i++; $i <= $count) {
        $this
          ->assertSession()
          ->elementTextEquals('xpath', "(//div[@class='dropbutton-wrapper']//input[@type='submit'])[{$i}]", $buttons[$i - 1]);
      }
    }
    else {

      // Assert there is a save button.
      $this
        ->assertSession()
        ->buttonExists('Save');
      $this
        ->assertSession()
        ->responseNotContains('dropbutton-wrapper');
    }
  }

}