class LazyBuilderPlaceholderTest

class LazyBuilderPlaceholderTest extends KernelTestBase {
  
  /**
   * {@inheritdoc}
   */
  protected static $modules = [
    'system',
    'twig_fibers_test',
  ];
  
  /**
   * {@inheritdoc}
   */
  protected function setUp() : void {
    parent::setUp();
    $this->installConfig([
      'system',
    ]);
  }
  
  /**
   * Tests Fiber::suspend() during twig rendering via placeholders.
   */
  public function testNestedLazyBuilderPlaceholders() : void {
    $render_array = $this->buildRenderArray();
    $output_string = (string) \Drupal::service('renderer')->renderRoot($render_array);
    $items = [
      '<div>Lazy builder content with param1</div>',
      'First Fibers test: param2',
      'Second Fibers test: param2',
      '<div>Lazy builder content with param3</div>',
      'First Fibers test: param4',
      'Second Fibers test: param4',
    ];
    $this->assertStringOrder($items, $output_string);
  }
  
  /**
   * Asserts the order of an array of strings inside a string.
   *
   * @param array $items
   *   The array of strings.
   * @param array $haystack
   *   The string that should contain $items in order.
   *
   * @todo use a generic assertion once available.
   * @see https://www.drupal.org/project/drupal/issues/2817657
   */
  protected function assertStringOrder(array $items, string $haystack) : void {
    $strings = [];
    foreach ($items as $item) {
      if (($pos = strpos($haystack, $item)) === FALSE) {
        $this->fail("Cannot find '{$item}' in the page");
      }
      $strings[$pos] = $item;
    }
    ksort($strings);
    $ordered = implode(', ', array_map(function ($item) {
      return "'{$item}'";
    }, $items));
    $this->assertSame($items, array_values($strings), "Found strings, ordered as: {$ordered}.");
  }
  
  /**
   * Builds a render array with placeholdered lazy builder callbacks.
   *
   * @return array
   *   The render array with three elements containing lazy builders.
   */
  protected function buildRenderArray() : array {
    return [
      '#type' => 'container',
      'element_1' => [
        '#lazy_builder' => [
          static::class . '::lazyBuilderCallback',
          [
            'param1',
          ],
        ],
        '#create_placeholder' => TRUE,
      ],
      'element_2' => [
        '#lazy_builder' => [
          static::class . '::twigFiberSuspendLazyBuilderCallback',
          [
            'param2',
          ],
        ],
        '#create_placeholder' => TRUE,
      ],
      'element_3' => [
        '#lazy_builder' => [
          static::class . '::lazyBuilderCallback',
          [
            'param3',
          ],
        ],
        '#create_placeholder' => TRUE,
      ],
      'element_4' => [
        '#lazy_builder' => [
          static::class . '::twigFiberSuspendLazyBuilderCallback',
          [
            'param4',
          ],
        ],
        '#create_placeholder' => TRUE,
      ],
    ];
  }
  
  /**
   * Lazy builder callback.
   *
   * @param string $param
   *   A parameter for the callback.
   *
   * @return array
   *   A render array.
   */
  public static function lazyBuilderCallback(string $param) : array {
    return [
      '#type' => 'container',
      '#markup' => 'Lazy builder content with ' . $param,
    ];
  }
  
  /**
   * Lazy builder callback with test template.
   *
   * @param string $param
   *   A parameter for the callback.
   *
   * @return array
   *   A render array containing another lazy builder.
   */
  public static function twigFiberSuspendLazyBuilderCallback(string $param) : array {
    return [
      '#type' => 'inline_template',
      '#template' => '<div class="fibers-test">
  First {{ fibers_test_function(message) }}
  Second {{ fibers_test_function(message) }}
</div>',
      '#context' => [
        'message' => $param,
      ],
    ];
  }

}