@Test public void shouldReturnTrueIfTreeIsBalanced() {

  BinaryNode<Integer> root = new BinaryNode<Integer>(0);
  BinaryNode<Integer> n1 = new BinaryNode<Integer>(1);
  BinaryNode<Integer> n2 = new BinaryNode<Integer>(2);
  BinaryNode<Integer> n3 = new BinaryNode<Integer>(3);
  BinaryNode<Integer> n4 = new BinaryNode<Integer>(4);
  root.setLeft(n1);
  root.setRight(n2);
  n1.setLeft(n3);
  n2.setRight(n4);
  boolean isBalanced = isTreeBalanced.check(root);
  assertTrue(isBalanced);
}