public static void Run(List <int> numbers, int x, IConsole console)
        {
            var tuples = AdditionPairs.GetPairs(numbers, x);

            if (tuples.Count() > 0)
            {
                console.Out.WriteLine($"Pairs of numbers that can be added to get { x }:");
                foreach (Tuple <int, int> tuple in tuples)
                {
                    console.Out.WriteLine($"{ tuple.Item1 }, { tuple.Item2 }");
                }
            }
            else
            {
                console.Out.WriteLine($"No addition pairs found for { x }");
            }
        }
        public void GetPairs_WhenNumbersIsNull_ThrowsArgumentNullException()
        {
            Action actual = () => AdditionPairs.GetPairs(null, 0);

            Assert.Throws <ArgumentNullException>(actual);
        }
        public void GetPairs_WhenNumbersIsNotNull_ReturnsValidResult(List <int> numbers, int X, List <Tuple <int, int> > expected)
        {
            var actual = AdditionPairs.GetPairs(numbers, X);

            Assert.Equal(expected, actual);
        }