public void Should_Validate_Valid_Character(char input) {
            // Arrange
            var validator = new ThumbprintCharacterValidator();

            // Act
            var result = validator.IsValid(input);

            // Assert
            result.ShouldNotBeNull();
            result.Valid.ShouldBeTrue();
            result.ErrorMessages.ShouldNotBeNull();
            result.ErrorMessages.ShouldBeEmpty();
        }
        public void Should_Identify_Invalid_Character_In_Input(char input) {
            // Arrange
            var validator = new ThumbprintCharacterValidator();

            // Act
            var result = validator.IsValid(input);
            
            // Assert
            result.ShouldNotBeNull();
            result.Valid.ShouldBeFalse();
            result.ErrorMessages.ShouldNotBeNull();
            result.ErrorMessages.ShouldNotBeEmpty();
            result.ErrorMessages.Count.ShouldEqual(1);
            result.ErrorMessages.Single().ParamName.ShouldEqual("input");
            result.ErrorMessages.Single().Message.ShouldEqual(string.Format("The character '\\u{0:X4}' is not valid in this context.", (int)input));
        }