public void CalculateProperDivisors() { var expectedDivisors = new List <long> { 1, 2, 4, 5, 10, 11, 20, 22, 44, 55, 110 }; var properDivisors = Factors.CalculateProperDivisors(220); CollectionAssert.AreEqual(expectedDivisors, properDivisors); }