class NormalizableTraversableDummy

SerializerTest.php in drupal/core/vendor/symfony/serializer/Symfony/Component/Serializer/Tests/SerializerTest.php

class NormalizableTraversableDummy extends TraversableDummy implements NormalizableInterface, DenormalizableInterface {
  public function normalize(NormalizerInterface $normalizer, $format = null) {
    return array(
      'foo' => 'normalizedFoo',
      'bar' => 'normalizedBar',
    );
  }
  public function denormalize(DenormalizerInterface $denormalizer, $data, $format = null) {
    return array(
      'foo' => 'denormalizedFoo',
      'bar' => 'denormalizedBar',
    );
  }

}