--- /dev/null
+<?php
+
+namespace Drupal\Tests\system\Functional\Menu;
+
+use Drupal\Component\Utility\Html;
+use Drupal\Core\Url;
+
+/**
+ * Provides test assertions for verifying breadcrumbs.
+ */
+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\simpletest\WebTestBase::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\simpletest\WebTestBase::assertTitle(). 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 $tree is expected to be active (TRUE)
+ * or just to be in the active trail (FALSE).
+ */
+ protected function assertBreadcrumb($goto, array $trail, $page_title = NULL, array $tree = [], $last_active = TRUE) {
+ if (isset($goto)) {
+ $this->drupalGet($goto);
+ }
+ $this->assertBreadcrumbParts($trail);
+
+ // Additionally assert page title, if given.
+ if (isset($page_title)) {
+ $this->assertTitle(strtr('@title | Drupal', ['@title' => $page_title]));
+ }
+
+ // Additionally assert active trail in a menu tree output, if given.
+ if ($tree) {
+ $this->assertMenuActiveTrail($tree, $last_active);
+ }
+ }
+
+ /**
+ * 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;
+ // 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, format_string('Breadcrumb %parts found on @path.', [
+ '%parts' => implode(' ยป ', $trail),
+ '@path' => $this->getUrl(),
+ ]));
+ }
+
+ /**
+ * Returns the breadcrumb contents of the current page in the internal browser.
+ */
+ protected function getBreadcrumbParts() {
+ $parts = [];
+ $elements = $this->xpath('//nav[@class="breadcrumb"]/ol/li/a');
+ if (!empty($elements)) {
+ foreach ($elements as $element) {
+ $parts[] = [
+ 'text' => $element->getText(),
+ 'href' => $element->getAttribute('href'),
+ 'title' => $element->getAttribute('title'),
+ ];
+ }
+ }
+ return $parts;
+ }
+
+}