Issue #3355604 by joachim, penyaskito, borisson_:...

namespace Drupal\Tests\content_translation\Functional;

use Drupal\Core\Language\LanguageInterface;

use Drupal\language\Entity\ConfigurableLanguage;

use Drupal\language\Entity\ContentLanguageSettings;

use Drupal\Tests\image\Kernel\ImageFieldCreationTrait;

use Drupal\Tests\node\Functional\NodeTestBase;

use Drupal\Tests\TestFileCreationTrait;

 */

class ContentTranslationLanguageChangeTest extends NodeTestBase {

  use ImageFieldCreationTrait;

  use TestFileCreationTrait {

    getTestFiles as drupalGetTestFiles;

  }

    $this->drupalLogin($user);

    // Enable translation for article.

    $edit = [

      'entity_types[node]' => TRUE,

      'settings[node][article][translatable]' => TRUE,

      'settings[node][article][settings][language][language_alterable]' => TRUE,

    ];

    $this->drupalGet('admin/config/regional/content-language');

    $this->submitForm($edit, 'Save configuration');

    $config = ContentLanguageSettings::loadByEntityTypeBundle('node', 'article');

    $config->setDefaultLangcode(LanguageInterface::LANGCODE_SITE_DEFAULT);

    $config->setLanguageAlterable(TRUE);

    $config->save();

    $content_translation_manager = $this->container->get('content_translation.manager');

    $content_translation_manager->setEnabled('node', 'article', TRUE);

    $content_translation_manager->setBundleTranslationSettings('node', 'article', [

      'untranslatable_fields_hide' => FALSE,

    ]);

    // Add an image field.

    $this->drupalGet('admin/structure/types/manage/article/fields/add-field');

    $edit = [

      'new_storage_type' => 'image',

      'field_name' => 'image_field',

      'label' => 'image_field',

    ];

    $this->submitForm($edit, 'Save and continue');

    $this->submitForm([], 'Save field settings');

    $this->submitForm([], 'Save settings');

    $this->rebuildContainer();

    $this->createImageField('field_image_field', 'article');

  }

  /**