drush_plugin__composer_check/ComposerCheck/YamlReporter.php

<?php

namespace Fgm\ComposerCheck;

use Symfony\Component\Yaml\Yaml;

/**
 * Class YamlReporter formats a requirements set as YAML.
 */
class YamlReporter extends ReporterBase {

  /**
   * {@inheritdoc}
   */
  public function report(MergeBox $mergeBox) : string {
    $yaml = Yaml::dump($mergeBox->getRows(), 3);
    return $yaml;
  }

}