OEL-452: Add MultilingualBlockTest.php and save progress.

tests/src/Kernel/MultilingualBlockTest.php

+<?php
+
+declare(strict_types = 1);
+
+namespace Drupal\Tests\oe_whitelabel\Kernel;
+
+use Drupal\KernelTests\KernelTestBase;
+use Symfony\Component\DomCrawler\Crawler;
+
+/**
+ * Tests the OE Multilingual Block rendering.
+ */
+class MultilingualBlockTest extends KernelTestBase {
+
+  /**
+   * {@inheritdoc}
+   */
+  protected static $modules = [
+    'block',
+    'components',
+    'content_translation',
+    'ctools',
+    'language',
+    'locale',
+    'node',
+    'oe_multilingual',
+    'path',
+    'pathauto',
+    'path_alias',
+    'system',
+    'token',
+    'ui_patterns',
+    'ui_patterns_library',
+    'user',
+  ];
+
+  /**
+   * {@inheritdoc}
+   */
+  protected function setUp(): void {
+    parent::setUp();
+    /** @var \Drupal\Core\Extension\ThemeInstallerInterface $theme_installer */
+    \Drupal::service('theme_installer')->install(['oe_whitelabel']);
+
+    \Drupal::configFactory()
+      ->getEditable('system.theme')
+      ->set('default', 'oe_whitelabel')
+      ->save();
+
+    $this->container->set('theme.registry', NULL);
+    $this->container->get('cache.render')->deleteAll();
+  }
+
+  /**
+   * Tests the rendering of blocks.
+   */
+  public function testBlockRendering(): void {
+    $entity_type_manager = $this->container
+      ->get('entity_type.manager')
+      ->getStorage('block');
+    $entity = $entity_type_manager->create([
+      'id' => 'languageswitchercontent',
+      'theme' => 'oe_whitelabel',
+      'plugin' => 'language_block:language_content',
+      'settings' => [
+        'id' => 'language_block:language_content',
+        'label' => 'Language switcher (Content)',
+        'provider' => 'language',
+        'label_display' => '0',
+      ],
+    ]);
+    $entity->save();
+    $builder = \Drupal::entityTypeManager()->getViewBuilder('block');
+    $build = $builder->view($entity, 'block');
+    $render = $this->container->get('renderer')->renderRoot($build);
+    print_r($render);
+    $crawler = new Crawler($render->__toString());
+
+    $actual = $crawler->filter('#block-languageswitchercontent');
+    $this->assertCount(1, $actual);
+    $link = $crawler->filter('a');
+    $this->assertSame('English', $link->text());
+    $this->assertSame('English', $link->href());
+  }
+
+}