public void Can_preorder_traverse() { // Arrange BinarySearchTree <int> testTree = new BinarySearchTree <int>(); testTree.Add(5); testTree.Add(9); testTree.Add(1); IEnumerable <int> expected = new int[] { 5, 1, 9 }; // Act IEnumerable <int> actual = testTree.PreOrder(testTree.ReturnRoot()); // Assert Assert.Equal(expected, actual); }