public void SummingTests(int combinationSize, IEnumerable <int> numbers, IEnumerable <int> expectedCombination,
                                 int finalSum)
        {
            var expenseReport = new ExpenseReport();
            var res           = expenseReport.GetSummableTo(numbers, finalSum, combinationSize);

            Assert.Equal(expectedCombination.Count(), res.Count());

            foreach (var i in expectedCombination)
            {
                Assert.Contains(i, res);
            }

            Assert.Equal(finalSum, res.Sum());
        }