TestInlineTemplateFormBlock.php

<?php

namespace Drupal\layout_builder_form_block_test\Plugin\Block;

use Drupal\Core\Block\Attribute\Block;
use Drupal\Core\Block\BlockBase;
use Drupal\Core\StringTranslation\TranslatableMarkup;

/**
 * Provides a block containing inline template with <form> tag.
 *
 * For use in Layout Builder tests.
 */
class TestInlineTemplateFormBlock extends BlockBase {
    
    /**
     * {@inheritdoc}
     */
    public function build() {
        $build['form'] = [
            '#type' => 'inline_template',
            '#template' => '<form method="POST"><label>{{ "Keywords"|t }}<input name="keyword" type="text" required /></label><input name="submit" type="submit" value="{{ "Submit"|t }}" /></form>',
        ];
        return $build;
    }

}