SystemConfigFormTest.php

<?php

namespace Drupal\Tests\system\Functional\Form;

use Drupal\Tests\BrowserTestBase;

/**
 * Tests the SystemConfigFormTestBase class.
 *
 * @group Form
 */
class SystemConfigFormTest extends BrowserTestBase {
    
    /**
     * Modules to enable.
     *
     * @var array
     */
    protected static $modules = [
        'form_test',
    ];
    
    /**
     * {@inheritdoc}
     */
    protected $defaultTheme = 'stark';
    
    /**
     * Tests the SystemConfigFormTestBase class.
     */
    public function testSystemConfigForm() {
        $this->drupalGet('form-test/system-config-form');
        // Verify the primary action submit button is found.
        $this->assertSession()
            ->elementExists('xpath', "//div[@id = 'edit-actions']/input[contains(@class, 'button--primary')]");
        $this->submitForm([], 'Save configuration');
        $this->assertSession()
            ->pageTextContains('The configuration options have been saved.');
    }

}