public void NumberJumbler_GivenCharactersInput_ThrowsArgumentException()
        {
            // Arrange
            var input = "hello";
            var jumbler = new NumberJumbler(null);

            // Action
            var result = jumbler.Jumble(input);
        }
        public void NumberJumbler_GivenNullInput_ThrowsArgumentNullException()
        {
            // Arrange
            string input = null;
            var jumbler = new NumberJumbler(null);

            // Action
            var result = jumbler.Jumble(input);
        }
        public void NumberJumbler_GivenANumber_DigitsReversed(string inputNumber, string expected)
        {
            // Arrange
            var jumbler = new NumberJumbler(null);

            // Action
            var result = jumbler.Jumble(inputNumber);

            // Assert
            Assert.AreEqual(expected, result, "Number not reversed");
        }