public void Nullify_card_security_code(string securityCode)
        {
            var cardDetails = new CardDetails {
                SecurityCode = securityCode
            };

            var result = new CardDetailsMasker().Mask(cardDetails);

            Assert.IsNull(result.CardNumber);
        }
        public void Mask_card_number(string cardNumber, string expectedMaskedCardNumber)
        {
            var cardDetails = new CardDetails {
                CardNumber = cardNumber
            };

            var result = new CardDetailsMasker().Mask(cardDetails);

            Assert.That(result.CardNumber, Is.EqualTo(expectedMaskedCardNumber));
        }