getPreviewFallbackString example

      // Hide contextual links for inline blocks until the UX issues surrounding       // editing them directly are resolved.       // @see https://www.drupal.org/project/drupal/issues/3075308       if (!$block instanceof InlineBlock && !empty($content['#contextual_links'])) {
        $build['#contextual_links'] = $content['#contextual_links'];
      }
      $build['content'] = $content;

      if ($event->inPreview()) {
        if ($block instanceof PreviewFallbackInterface) {
          $preview_fallback_string = $block->getPreviewFallbackString();
        }
        else {
          $preview_fallback_string = $this->t('"@block" block', ['@block' => $block->label()]);
        }
        // @todo Use new label methods so         // data-layout-content-preview-placeholder-label doesn't have to use         // preview fallback in https://www.drupal.org/node/2025649.         $build['#attributes']['data-layout-content-preview-placeholder-label'] = $preview_fallback_string;

        if ($is_content_empty && $is_placeholder_ready) {
          $build['content']['#markup'] = $this->t('Placeholder for the @preview_fallback', ['@preview_fallback' => $block->getPreviewFallbackString()]);
        }

if (!isset($extra_fields['display'][$this->fieldName])) {
      $build = [];
    }
    else {
      $build = [
        '#extra_field_placeholder_field_name' => $this->fieldName,
        // Always provide a placeholder. The Layout Builder will NOT invoke         // hook_entity_view_alter() so extra fields will not be added to the         // render array. If the hook is invoked the placeholder will be         // replaced.         // @see ::replaceFieldPlaceholder()         '#markup' => $this->t('Placeholder for the @preview_fallback', ['@preview_fallback' => $this->getPreviewFallbackString()]),
      ];
    }
    CacheableMetadata::createFromObject($this)->applyTo($build);
    return $build;
  }

  /** * {@inheritdoc} */
  public function getPreviewFallbackString() {
    $entity = $this->getEntity();
    

$access_result = AccessResult::allowed();
    $block->access($this->account->reveal(), TRUE)->willReturn($access_result);
    $block->build()->willReturn($block_content);
    $block->getCacheContexts()->willReturn([]);
    $block->getCacheTags()->willReturn([]);
    $block->getCacheMaxAge()->willReturn(Cache::PERMANENT);
    $block->getPluginId()->willReturn('block_plugin_id');
    $block->getBaseId()->willReturn('block_plugin_id');
    $block->getDerivativeId()->willReturn(NULL);
    $block->getConfiguration()->willReturn([]);
    $block->getPreviewFallbackString()->willReturn($placeholder_label);

    $section = [
      new SectionComponent('some_uuid', 'content', ['id' => 'block_plugin_id']),
    ];
    $expected = [
      'content' => [
        'some_uuid' => $render_array,
      ],
    ];
    $result = (new Section('layout_onecol', [], $section))->toRenderArray();
    $this->assertEquals($expected, $result);
  }

    $access_result = AccessResult::allowed();
    $block->access($this->account->reveal(), TRUE)->willReturn($access_result)->shouldBeCalled();
    $block->getCacheContexts()->willReturn([]);
    $block->getCacheTags()->willReturn(['test']);
    $block->getCacheMaxAge()->willReturn(Cache::PERMANENT);
    $block->getConfiguration()->willReturn([]);
    $block->getPluginId()->willReturn('block_plugin_id');
    $block->getBaseId()->willReturn('block_plugin_id');
    $block->getDerivativeId()->willReturn(NULL);
    $placeholder_label = 'Placeholder Label';
    $block->getPreviewFallbackString()->willReturn($placeholder_label);

    $block_content = [
      '#markup' => 'The block content.',
      '#cache' => ['tags' => ['build-tag']],
    ];
    $block->build()->willReturn($block_content);
    $this->blockManager->createInstance('some_block_id', ['id' => 'some_block_id'])->willReturn($block->reveal());

    $component = new SectionComponent('some-uuid', 'some-region', ['id' => 'some_block_id']);
    $in_preview = FALSE;
    $event = new SectionComponentBuildRenderArrayEvent($component, $contexts, $in_preview);

    

  public function testGetPreviewFallbackString() {
    $plugin_definition = [
      'provider' => 'views',
    ];
    $plugin_id = 'views_block:test_view_block-block_1';
    $views_block = ViewsBlock::create($this->container, [], $plugin_id, $plugin_definition);

    $this->assertEquals('"test_view_block::block_1" views block', $views_block->getPreviewFallbackString());
  }

}