class ConfigFormOverrideTest

class ConfigFormOverrideTest extends BrowserTestBase {
  
  /**
   * {@inheritdoc}
   */
  protected $defaultTheme = 'stark';
  
  /**
   * Tests that overrides do not affect forms.
   */
  public function testFormsWithOverrides() {
    $this->drupalLogin($this->drupalCreateUser([
      'access administration pages',
      'administer site configuration',
    ]));
    $overridden_name = 'Site name global conf override';
    // Set up an override.
    $settings['config']['system.site']['name'] = (object) [
      'value' => $overridden_name,
      'required' => TRUE,
    ];
    $this->writeSettings($settings);
    // Test that everything on the form is the same, but that the override
    // worked for the actual site name.
    $this->drupalGet('admin/config/system/site-information');
    $this->assertSession()
      ->titleEquals('Basic site settings | ' . $overridden_name);
    $this->assertSession()
      ->fieldValueEquals("site_name", 'Drupal');
    // Submit the form and ensure the site name is not changed.
    $edit = [
      'site_name' => 'Custom site name',
    ];
    $this->drupalGet('admin/config/system/site-information');
    $this->submitForm($edit, 'Save configuration');
    $this->assertSession()
      ->titleEquals('Basic site settings | ' . $overridden_name);
    $this->assertSession()
      ->fieldValueEquals("site_name", $edit['site_name']);
  }

}