public void Test_ContainsInTree()
{
var tree = new BinaryTree<int>() { 1, 5, 3, 4, 9 };
Assert.AreEqual(tree.Contains(new BinaryTreeNode<int>(5)), true);
Assert.AreEqual(tree.Contains(new BinaryTreeNode<int>(77)), false);
Assert.AreEqual(tree.Contains(5), true);
Assert.AreEqual(tree.Contains(77), false);
}