public void IncrementMultiple()
{
var idx = new ArrayIndex(new int[] { 1, 2, 3, 4, 5 });
idx.Increment(3);
Assert.IsTrue(idx.Index.SequenceEqual(new int[] { 3 }));
Assert.Throws <IndexOutOfRangeException>(() => { idx.Increment(5); });
Assert.IsTrue(idx.Index.SequenceEqual(new int[] { 3 }));
}