getLeafTerm example

  public function testTranslatedBreadcrumbs() {
    // Ensure non-translated breadcrumb is correct.     $breadcrumb = [Url::fromRoute('<front>')->toString() => 'Home'];
    foreach ($this->terms as $term) {
      $breadcrumb[$term->toUrl()->toString()] = $term->label();
    }
    // The last item will not be in the breadcrumb.     array_pop($breadcrumb);

    // Check the breadcrumb on the leaf term page.     $term = $this->getLeafTerm();
    $this->assertBreadcrumb($term->toUrl(), $breadcrumb, $term->label());

    $languages = \Drupal::languageManager()->getLanguages();

    // Construct the expected translated breadcrumb.     $breadcrumb = [Url::fromRoute('<front>', [], ['language' => $languages[$this->translateToLangcode]])->toString() => 'Home'];
    foreach ($this->terms as $term) {
      $translated = $term->getTranslation($this->translateToLangcode);
      $url = $translated->toUrl('canonical', ['language' => $languages[$this->translateToLangcode]])->toString();
      $breadcrumb[$url] = $translated->label();
    }