class UserFieldsTest

class UserFieldsTest extends KernelTestBase {
  
  /**
   * Modules to enable.
   *
   * @var array
   */
  protected static $modules = [
    'user',
    'system',
  ];
  
  /**
   * {@inheritdoc}
   */
  protected function setUp() : void {
    parent::setUp();
    $this->installEntitySchema('user');
    // Set up a test theme that prints the user's mail field.
    \Drupal::service('theme_installer')->install([
      'user_test_theme',
    ]);
    \Drupal::theme()->setActiveTheme(\Drupal::service('theme.initialization')->initTheme('user_test_theme'));
    // Clear the theme registry.
    $this->container
      ->set('theme.registry', NULL);
  }
  
  /**
   * Tests account's available fields.
   */
  public function testUserFields() {
    // Create the user to test the user fields.
    $user = User::create([
      'name' => 'foobar',
      'mail' => 'foobar@example.com',
    ]);
    $build = \Drupal::entityTypeManager()->getViewBuilder('user')
      ->view($user);
    $output = \Drupal::service('renderer')->renderRoot($build);
    $this->setRawContent($output);
    $userEmail = $user->getEmail();
    $this->assertText($userEmail, "User's mail field is found in the twig template");
  }

}