public void FindAllTest()
{
Tree<string> tested = new Tree<string>();
TreeNode<string> root = tested.SetRoot("A");
root.AddChild("B");
root.AddChild("C");
int actualCount = tested.FindAll ((x) => x.Equals ("A") || x.Equals("B")).Count;
int expectedCount = 2;
Assert.AreEqual(expectedCount, actualCount);
}