class LanguageNegotiationSessionTest

class LanguageNegotiationSessionTest extends BrowserTestBase {
  
  /**
   * An administrative user to configure the test environment.
   *
   * @var \Drupal\user\Entity\User
   */
  protected $adminUser;
  
  /**
   * {@inheritdoc}
   */
  protected static $modules = [
    'language',
  ];
  
  /**
   * {@inheritdoc}
   */
  protected $defaultTheme = 'stark';
  
  /**
   * {@inheritdoc}
   */
  protected function setUp() : void {
    parent::setUp();
    // Create a new user with permission to manage the languages.
    $this->adminUser = $this->drupalCreateUser([
      'administer languages',
    ]);
    $this->drupalLogin($this->adminUser);
    ConfigurableLanguage::createFromLangcode('fr')->save();
  }
  
  /**
   * Tests language negotiation via query/session parameters.
   */
  public function testSessionLanguageNegotiationMethod() {
    // Enable Session and Selected language for interface language detection.
    $this->drupalGet('admin/config/regional/language/detection');
    $edit = [
      'language_interface[enabled][language-session]' => 1,
      'language_interface[enabled][language-selected]' => 1,
      'language_interface[weight][language-session]' => -6,
      'language_interface[weight][language-selected]' => 12,
    ];
    $this->submitForm($edit, 'Save settings');
    // Set language via query parameter.
    $this->drupalGet('user/' . $this->adminUser
      ->id(), [
      'query' => [
        'language' => 'fr',
      ],
    ]);
    $this->assertSession()
      ->statusCodeEquals(200);
    $this->assertSession()
      ->responseHeaderEquals('Content-language', 'fr');
    // Verify that the language is persisted in the session.
    $this->drupalGet('user/' . $this->adminUser
      ->id());
    $this->assertSession()
      ->statusCodeEquals(200);
    $this->assertSession()
      ->responseHeaderEquals('Content-language', 'fr');
    // Set language via query parameter.
    $this->drupalGet('user/' . $this->adminUser
      ->id(), [
      'query' => [
        'language' => 'en',
      ],
    ]);
    $this->assertSession()
      ->statusCodeEquals(200);
    $this->assertSession()
      ->responseHeaderEquals('Content-language', 'en');
    // Verify that the language is persisted in the session.
    $this->drupalGet('admin/config/regional/language');
    $this->assertSession()
      ->statusCodeEquals(200);
    $this->assertSession()
      ->responseHeaderEquals('Content-language', 'en');
  }

}