public static void GetKeysPreOrder_MultipleKeys_ReturnsAllKeysInCorrectOrder() { var tree = new BinarySearchTree <int>(); tree.AddRange(new List <int> { 5, 3, 4, 2, 7, 6, 8 }); var keys = tree.GetKeysPreOrder(); var expected = new List <int> { 5, 3, 2, 4, 7, 6, 8 }; Assert.IsTrue(keys.SequenceEqual(expected)); }