public static void AssertContainsExactly <TItem>(this IEnumerable <TItem> items, params TItem[] expected)
 {
     CollectionAssertExtensions.AreEqual(expected, items.ToArray());
 }
 public static void AssertContainsInAnyOrder <TItem>(this IEnumerable <TItem> items, params TItem[] expected)
 {
     CollectionAssertExtensions.AreEquivalent(expected, items.ToArray());
 }