class FormDefaultHandlersTest

class FormDefaultHandlersTest extends KernelTestBase implements FormInterface {
  
  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'test_form_handlers';
  }
  
  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state) {
    $form['#validate'][] = '::customValidateForm';
    $form['#submit'][] = '::customSubmitForm';
    $form['submit'] = [
      '#type' => 'submit',
      '#value' => 'Save',
    ];
    return $form;
  }
  
  /**
   * {@inheritdoc}
   */
  public function customValidateForm(array &$form, FormStateInterface $form_state) {
    $test_handlers = $form_state->get('test_handlers');
    $test_handlers['validate'][] = __FUNCTION__;
    $form_state->set('test_handlers', $test_handlers);
  }
  
  /**
   * {@inheritdoc}
   */
  public function validateForm(array &$form, FormStateInterface $form_state) {
    $test_handlers = $form_state->get('test_handlers');
    $test_handlers['validate'][] = __FUNCTION__;
    $form_state->set('test_handlers', $test_handlers);
  }
  
  /**
   * {@inheritdoc}
   */
  public function customSubmitForm(array &$form, FormStateInterface $form_state) {
    $test_handlers = $form_state->get('test_handlers');
    $test_handlers['submit'][] = __FUNCTION__;
    $form_state->set('test_handlers', $test_handlers);
  }
  
  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $test_handlers = $form_state->get('test_handlers');
    $test_handlers['submit'][] = __FUNCTION__;
    $form_state->set('test_handlers', $test_handlers);
  }
  
  /**
   * Tests that default handlers are added even if custom are specified.
   */
  public function testDefaultAndCustomHandlers() {
    $form_state = new FormState();
    $form_builder = $this->container
      ->get('form_builder');
    $form_builder->submitForm($this, $form_state);
    $handlers = $form_state->get('test_handlers');
    $this->assertCount(2, $handlers['validate']);
    $this->assertSame('customValidateForm', $handlers['validate'][0]);
    $this->assertSame('validateForm', $handlers['validate'][1]);
    $this->assertCount(2, $handlers['submit']);
    $this->assertSame('customSubmitForm', $handlers['submit'][0]);
    $this->assertSame('submitForm', $handlers['submit'][1]);
  }

}