class AuditResult

class AuditResult implements MarkupInterface, \Countable {
    
    /**
     * The audited migration.
     *
     * @var \Drupal\migrate\Plugin\MigrationInterface
     */
    protected $migration;
    
    /**
     * The result of the audit (TRUE if passed, FALSE otherwise).
     *
     * @var bool
     */
    protected $status;
    
    /**
     * The reasons why the migration passed or failed the audit.
     *
     * @var string[]
     */
    protected $reasons = [];
    
    /**
     * AuditResult constructor.
     *
     * @param \Drupal\migrate\Plugin\MigrationInterface $migration
     *   The audited migration.
     * @param bool $status
     *   The result of the audit (TRUE if passed, FALSE otherwise).
     * @param string[] $reasons
     *   (optional) The reasons why the migration passed or failed the audit.
     */
    public function __construct(MigrationInterface $migration, $status, array $reasons = []) {
        if (!is_bool($status)) {
            throw new \InvalidArgumentException('Audit results must have a boolean status.');
        }
        $this->migration = $migration;
        $this->status = $status;
        array_walk($reasons, [
            $this,
            'addReason',
        ]);
    }
    
    /**
     * Returns the audited migration.
     *
     * @return \Drupal\migrate\Plugin\MigrationInterface
     *   The audited migration.
     */
    public function getMigration() {
        return $this->migration;
    }
    
    /**
     * Returns the boolean result of the audit.
     *
     * @return bool
     *   The result of the audit. TRUE if the migration passed the audit, FALSE
     *   otherwise.
     */
    public function passed() {
        return $this->status;
    }
    
    /**
     * Adds a reason why the migration passed or failed the audit.
     *
     * @param string|object $reason
     *   The reason to add. Can be a string or a string-castable object.
     *
     * @return $this
     */
    public function addReason($reason) {
        array_push($this->reasons, (string) $reason);
        return $this;
    }
    
    /**
     * Creates a passing audit result for a migration.
     *
     * @param \Drupal\migrate\Plugin\MigrationInterface $migration
     *   The audited migration.
     * @param string[] $reasons
     *   (optional) The reasons why the migration passed the audit.
     *
     * @return static
     */
    public static function pass(MigrationInterface $migration, array $reasons = []) {
        return new static($migration, TRUE, $reasons);
    }
    
    /**
     * Creates a failing audit result for a migration.
     *
     * @param \Drupal\migrate\Plugin\MigrationInterface $migration
     *   The audited migration.
     * @param array $reasons
     *   (optional) The reasons why the migration failed the audit.
     *
     * @return static
     */
    public static function fail(MigrationInterface $migration, array $reasons = []) {
        return new static($migration, FALSE, $reasons);
    }
    
    /**
     * Implements \Countable::count() for Twig template compatibility.
     *
     * @return int
     *
     * @see \Drupal\Component\Render\MarkupInterface
     */
    public function count() : int {
        return count($this->reasons);
    }
    
    /**
     * Returns the reasons the migration passed or failed, as a string.
     *
     * @return string
     *
     * @see \Drupal\Component\Render\MarkupInterface
     */
    public function __toString() {
        return implode("\n", $this->reasons);
    }
    
    /**
     * Returns the reasons the migration passed or failed, for JSON serialization.
     *
     * @return string[]
     */
    public function jsonSerialize() : string {
        return $this->reasons;
    }

}