class LanguageNegotiationFormOverrideTest

class LanguageNegotiationFormOverrideTest extends BrowserTestBase {
  protected static $modules = [
    'language',
    'locale',
    'locale_test',
  ];
  
  /**
   * {@inheritdoc}
   */
  protected $defaultTheme = 'stark';
  
  /**
   * Tests that overrides do not affect language-negotiation form values.
   */
  public function testFormWithOverride() {
    $this->drupalLogin($this->rootUser);
    $overridden_value_en = 'whatever';
    $overridden_value_es = 'loquesea';
    // Set up an override.
    $settings['config']['language.negotiation']['url']['prefixes'] = (object) [
      'value' => [
        'en' => $overridden_value_en,
        'es' => $overridden_value_es,
      ],
      'required' => TRUE,
    ];
    $this->writeSettings($settings);
    // Add predefined language.
    $edit = [
      'predefined_langcode' => 'es',
    ];
    $this->drupalGet('admin/config/regional/language/add');
    $this->submitForm($edit, 'Add language');
    // Overridden string for language-negotiation should not exist in the form.
    $this->drupalGet('admin/config/regional/language/detection/url');
    // The language-negotiation form should be found.
    $this->assertSession()
      ->pageTextContains('Path prefix configuration');
    // The English override should not be found.
    $this->assertSession()
      ->fieldValueNotEquals('prefix[en]', $overridden_value_en);
    // Now check the Spanish version of the page for the same thing.
    $this->drupalGet($overridden_value_es . '/admin/config/regional/language/detection/url');
    // The language-negotiation form should be found.
    $this->assertSession()
      ->pageTextContains('Path prefix configuration');
    // The Spanish override should not be found.
    $this->assertSession()
      ->fieldValueNotEquals('prefix[es]', $overridden_value_es);
  }

}