trait TaxonomyTestTrait in Drupal 8

trait TaxonomyTestTrait {

  /**
   * Returns a new vocabulary with random properties.
   */
  public function createVocabulary() {

    // Create a vocabulary.
    $vocabulary = Vocabulary::create([
      'name' => $this
        ->randomMachineName(),
      'description' => $this
        ->randomMachineName(),
      'vid' => mb_strtolower($this
        ->randomMachineName()),
      'langcode' => LanguageInterface::LANGCODE_NOT_SPECIFIED,
      'weight' => mt_rand(0, 10),
    ]);
    $vocabulary
      ->save();
    return $vocabulary;
  }

  /**
   * Returns a new term with random properties in vocabulary $vid.
   *
   * @param \Drupal\taxonomy\Entity\Vocabulary $vocabulary
   *   The vocabulary object.
   * @param array $values
   *   (optional) An array of values to set, keyed by property name. If the
   *   entity type has bundles, the bundle key has to be specified.
   *
   * @return \Drupal\taxonomy\Entity\Term
   *   The new taxonomy term object.
   */
  public function createTerm(Vocabulary $vocabulary, $values = []) {
    $filter_formats = filter_formats();
    $format = array_pop($filter_formats);
    $term = Term::create($values + [
      'name' => $this
        ->randomMachineName(),
      'description' => [
        'value' => $this
          ->randomMachineName(),
        // Use the first available text format.
        'format' => $format
          ->id(),
      ],
      'vid' => $vocabulary
        ->id(),
      'langcode' => LanguageInterface::LANGCODE_NOT_SPECIFIED,
    ]);
    $term
      ->save();
    return $term;
  }

}