public void SequenceofElementsTest()
 {
     Assert.AreEqual(6, MissingInteger.Solution(Enumerable.Range(1, 5).ToArray()));
 }
 public void OneIsMissingTestTest()
 {
     Assert.AreEqual(1, MissingInteger.Solution(Enumerable.Range(2, 10).ToArray()));
 }
 public void ExampleTest()
 {
     Assert.AreEqual(5, MissingInteger.Solution(new [] { 1, 3, 6, 4, 1, 3, 2 }));
 }