private void ValidateRequest(CalculateGiftAidRequest request) { _logger.LogDebug("Validating request"); if (request == null) { throw new ArgumentNullException(nameof(request)); } if (request.DonationAmount < _donationConfig.MinDonationAmount) { throw DonationException.LessThanMinimum(request.DonationAmount, _donationConfig.MinDonationAmount); } if (request.DonationAmount >= _donationConfig.MaxDonationAmount) { throw DonationException.ExceedsMaximum(request.DonationAmount, _donationConfig.MaxDonationAmount); } }