public void AddsItemsToFilledCollection()
{
var collection = new Collection<int> { 1, 2, 3 };
var newList = new List<int> { 4, 5, 6 };
collection.AddRange(newList);
Assert.AreEqual(6, collection.Count);
Assert.AreEqual(1, collection[0]);
Assert.AreEqual(2, collection[1]);
Assert.AreEqual(3, collection[2]);
Assert.AreEqual(4, collection[3]);
Assert.AreEqual(5, collection[4]);
Assert.AreEqual(6, collection[5]);
}