public async Task ProperlyHandlesWrongNumber()
        {
            // Arrange
            var sut = new CardManagerTestable();

            // Act
            var validationResult = await sut.ValidateNumberAsync(InvalidCardNumber);

            // Assert
            Assert.Equal(CardNumberValidationResult.CardNotFoundOrLockedOut, validationResult);
        }
        public async Task ProperlyHandlesValidCard()
        {
            // Arrange
            var sut = new CardManagerTestable(isCardLocked: false);

            // Act
            var validationResult = await sut.ValidateNumberAsync(ValidCardNumber);

            // Assert
            Assert.Equal(CardNumberValidationResult.Ok, validationResult);
        }