public static void Remove_NullKey_ThrowsArgumentNullException()
{
SortedList sortList1 = Helpers.CreateIntSortedList(100);
Helpers.PerformActionOnAllSortedListWrappers(sortList1, sortList2 =>
{
Assert.Throws<ArgumentNullException>("key", () => sortList2.Remove(null)); // Key is null
});
}