class FormTestLabelForm

class FormTestLabelForm extends FormBase {
    
    /**
     * An array of elements that render a title.
     *
     * @var array
     */
    public static $typesWithTitle = [
        'checkbox',
        'checkboxes',
        'color',
        'date',
        'datelist',
        'datetime',
        'details',
        'email',
        'fieldset',
        'file',
        'item',
        'managed_file',
        'number',
        'password',
        'password_confirm',
        'radio',
        'radios',
        'range',
        'search',
        'select',
        'tel',
        'textarea',
        'textfield',
        'text_format',
        'url',
        'weight',
    ];
    
    /**
     * {@inheritdoc}
     */
    public function getFormId() {
        return 'form_label_test_form';
    }
    
    /**
     * {@inheritdoc}
     */
    public function buildForm(array $form, FormStateInterface $form_state) {
        $form['form_checkboxes_test'] = [
            '#type' => 'checkboxes',
            '#title' => t('Checkboxes test'),
            '#options' => [
                'first-checkbox' => t('First checkbox'),
                'second-checkbox' => t('Second checkbox'),
                'third-checkbox' => t('Third checkbox'),
                '0' => t('0'),
            ],
        ];
        $form['form_radios_test'] = [
            '#type' => 'radios',
            '#title' => t('Radios test'),
            '#options' => [
                'first-radio' => t('First radio'),
                'second-radio' => t('Second radio'),
                'third-radio' => t('Third radio'),
                '0' => t('0'),
            ],
            // Test #field_prefix and #field_suffix placement.
'#field_prefix' => '<span id="form-test-radios-field-prefix">' . t('Radios #field_prefix element') . '</span>',
            '#field_suffix' => '<span id="form-test-radios-field-suffix">' . t('Radios #field_suffix element') . '</span>',
        ];
        $form['form_checkbox_test'] = [
            '#type' => 'checkbox',
            '#title' => t('Checkbox test'),
        ];
        $form['form_textfield_test_title_and_required'] = [
            '#type' => 'textfield',
            '#title' => t('Textfield test for required with title'),
            '#required' => TRUE,
        ];
        $form['form_textfield_test_no_title_required'] = [
            '#type' => 'textfield',
            // We use an empty title, since not setting #title suppresses the label
            // and required marker.
'#title' => '',
            '#required' => TRUE,
        ];
        $form['form_textfield_test_title'] = [
            '#type' => 'textfield',
            '#title' => t('Textfield test for title only'),
            // Not required.
            // Test #prefix and #suffix placement.
'#prefix' => '<div id="form-test-textfield-title-prefix">' . t('Textfield #prefix element') . '</div>',
            '#suffix' => '<div id="form-test-textfield-title-suffix">' . t('Textfield #suffix element') . '</div>',
        ];
        $form['form_textfield_test_title_after'] = [
            '#type' => 'textfield',
            '#title' => t('Textfield test for title after element'),
            '#title_display' => 'after',
        ];
        $form['form_textfield_test_title_invisible'] = [
            '#type' => 'textfield',
            '#title' => t('Textfield test for invisible title'),
            '#title_display' => 'invisible',
        ];
        // Textfield test for title set not to display.
        $form['form_textfield_test_title_no_show'] = [
            '#type' => 'textfield',
        ];
        // Checkboxes & radios with title as attribute.
        $form['form_checkboxes_title_attribute'] = [
            '#type' => 'checkboxes',
            '#title' => 'Checkboxes test',
            '#title_display' => 'attribute',
            '#options' => [
                'first-checkbox' => 'First checkbox',
                'second-checkbox' => 'Second checkbox',
            ],
            '#required' => TRUE,
        ];
        $form['form_radios_title_attribute'] = [
            '#type' => 'radios',
            '#title' => 'Radios test',
            '#title_display' => 'attribute',
            '#options' => [
                'first-radio' => 'First radio',
                'second-radio' => 'Second radio',
            ],
            '#required' => TRUE,
        ];
        $form['form_checkboxes_title_invisible'] = [
            '#type' => 'checkboxes',
            '#title' => 'Checkboxes test invisible',
            '#title_display' => 'invisible',
            '#options' => [
                'first-checkbox' => 'First checkbox',
                'second-checkbox' => 'Second checkbox',
            ],
            '#required' => TRUE,
        ];
        $form['form_radios_title_invisible'] = [
            '#type' => 'radios',
            '#title' => 'Radios test invisible',
            '#title_display' => 'invisible',
            '#options' => [
                'first-radio' => 'First radio',
                'second-radio' => 'Second radio',
            ],
            '#required' => TRUE,
        ];
        foreach (static::$typesWithTitle as $type) {
            $form['form_' . $type . '_title_no_xss'] = [
                '#type' => $type,
                '#title' => "{$type} <script>alert('XSS')</script> is XSS filtered!",
            ];
            // Add keys that are required for some elements to be processed correctly.
            if (in_array($type, [
                'checkboxes',
                'radios',
            ], TRUE)) {
                $form['form_' . $type . '_title_no_xss']['#options'] = [];
            }
            if ($type === 'datetime') {
                $form['form_' . $type . '_title_no_xss']['#default_value'] = NULL;
            }
        }
        return $form;
    }
    
    /**
     * {@inheritdoc}
     */
    public function submitForm(array &$form, FormStateInterface $form_state) {
    }

}