@Test public void shouldCalculateBinaryTreeDepthEvenIfTreeContainsJustOneBigLeftBranch() {

  BinaryNode<Integer> root = new BinaryNode<Integer>(0);
  BinaryNode<Integer> n1 = new BinaryNode<Integer>(1);
  BinaryNode<Integer> n2 = new BinaryNode<Integer>(2);
  root.setLeft(n1);
  n1.setLeft(n2);
  int depth = binaryTreeDepth.get(root);
  assertEquals(3, depth);
}