AssertBlockAppearsTrait.php

<?php

namespace Drupal\Tests\block\Functional;

use Drupal\block\Entity\Block;
use Drupal\Component\Render\FormattableMarkup;

/**
 * Provides test assertions for testing block appearance.
 *
 * Can be used by test classes that extend \Drupal\Tests\BrowserTestBase.
 */
trait AssertBlockAppearsTrait {
    
    /**
     * Checks to see whether a block appears on the page.
     *
     * @param \Drupal\block\Entity\Block $block
     *   The block entity to find on the page.
     */
    protected function assertBlockAppears(Block $block) {
        $result = $this->findBlockInstance($block);
        $this->assertTrue(!empty($result), new FormattableMarkup('The block @id appears on the page', [
            '@id' => $block->id(),
        ]));
    }
    
    /**
     * Checks to see whether a block does not appears on the page.
     *
     * @param \Drupal\block\Entity\Block $block
     *   The block entity to find on the page.
     */
    protected function assertNoBlockAppears(Block $block) {
        $result = $this->findBlockInstance($block);
        $this->assertFalse(!empty($result), new FormattableMarkup('The block @id does not appear on the page', [
            '@id' => $block->id(),
        ]));
    }
    
    /**
     * Find a block instance on the page.
     *
     * @param \Drupal\block\Entity\Block $block
     *   The block entity to find on the page.
     *
     * @return array
     *   The result from the xpath query.
     */
    protected function findBlockInstance(Block $block) {
        return $this->xpath('//div[@id = :id]', [
            ':id' => 'block-' . $block->id(),
        ]);
    }

}