public void SeveralItemsAddRangedAndRemoveAlledShouldHaveBeenContained(params string[] items)
        {
            var sut = new MemoryList <string>();

            sut.AddRange(items);
            sut.RemoveAll(x => true);

            foreach (var item in items)
            {
                Assert.True(sut.HasEverContained(item));
            }
        }