trait AssertBreadcrumbTrait

trait AssertBreadcrumbTrait {
    use AssertMenuActiveTrailTrait;
    
    /**
     * Assert that a given path shows certain breadcrumb links.
     *
     * @param \Drupal\Core\Url|string $goto
     *   (optional) A path or URL to pass to
     *   \Drupal\Tests\UiHelperTrait::drupalGet().
     * @param array $trail
     *   An associative array whose keys are expected breadcrumb link paths and
     *   whose values are expected breadcrumb link texts (not sanitized).
     * @param string $page_title
     *   (optional) A page title to additionally assert via
     *   \Drupal\Tests\WebAssert::titleEquals(). Without site name suffix.
     * @param array $tree
     *   (optional) An associative array whose keys are link paths and whose
     *   values are link titles (not sanitized) of an expected active trail in a
     *   menu tree output on the page.
     * @param $last_active
     *   (optional) Whether the last link in $tree is expected to be active (TRUE)
     *   or just to be in the active trail (FALSE).
     * @param string $active_trail_class
     *   (optional) The class of the active trail. Defaults to
     *   'menu-item--active-trail'.
     * @param string $active_class
     *   (optional) The class of the active element. Defaults to 'is-active'.
     */
    protected function assertBreadcrumb($goto, array $trail, $page_title = NULL, array $tree = [], $last_active = TRUE, $active_trail_class = 'menu-item--active-trail', $active_class = 'is-active') {
        if (isset($goto)) {
            $this->drupalGet($goto);
        }
        $this->assertBreadcrumbParts($trail);
        // Additionally assert page title, if given.
        if (isset($page_title)) {
            $this->assertSession()
                ->titleEquals("{$page_title} | Drupal");
        }
        // Additionally assert active trail in a menu tree output, if given.
        if ($tree) {
            $this->assertMenuActiveTrail($tree, $last_active, $active_trail_class, $active_class);
        }
    }
    
    /**
     * Assert that a trail exists in the internal browser.
     *
     * @param array $trail
     *   An associative array whose keys are expected breadcrumb link paths and
     *   whose values are expected breadcrumb link texts (not sanitized).
     */
    protected function assertBreadcrumbParts($trail) {
        // Compare paths with actual breadcrumb.
        $parts = $this->getBreadcrumbParts();
        $pass = TRUE;
        // Fail if there is no breadcrumb and we have a trail.
        if (!empty($trail) && empty($parts)) {
            $pass = FALSE;
        }
        // There may be more than one breadcrumb on the page. If $trail is empty
        // this test would go into an infinite loop, so we need to check that too.
        while ($trail && !empty($parts)) {
            foreach ($trail as $path => $title) {
                // If the path is empty, generate the path from the <front> route.  If
                // the path does not start with a leading slash, then run it through
                // Url::fromUri('base:')->toString() to get the correct base
                // prepended.
                if ($path == '') {
                    $url = Url::fromRoute('<front>')->toString();
                }
                elseif ($path[0] != '/') {
                    $url = Url::fromUri('base:' . $path)->toString();
                }
                else {
                    $url = $path;
                }
                $part = array_shift($parts);
                $pass = $pass && $part['href'] === $url && $part['text'] === Html::escape($title);
            }
        }
        // No parts must be left, or an expected "Home" will always pass.
        $pass = $pass && empty($parts);
        $this->assertTrue($pass, new FormattableMarkup('Breadcrumb %parts found on @path.', [
            '%parts' => implode(' » ', $trail),
            '@path' => $this->getUrl(),
        ]));
    }
    
    /**
     * Returns the breadcrumb contents of the current page in the internal browser.
     */
    protected function getBreadcrumbParts() {
        $parts = [];
        $elements = $this->xpath('//nav[@aria-labelledby="system-breadcrumb"]//ol/li/a');
        if (!empty($elements)) {
            foreach ($elements as $element) {
                $parts[] = [
                    'text' => $element->getText(),
                    'href' => $element->getAttribute('href'),
                    'title' => $element->getAttribute('title'),
                ];
            }
        }
        return $parts;
    }

}