### Question:
BinaryTree { public boolean isEmpty() { return root == null; }  void add(int value); boolean isEmpty(); int getSize(); boolean containsNode(int value); void delete(int value); void traverseInOrder(Node node); void traversePreOrder(Node node); void traversePostOrder(Node node); void traverseLevelOrder();  }### Answer:
@Test public void givenABinaryTree_WhenAddingElements_ThenTreeNotEmpty() { BinaryTree bt = createBinaryTree(); assertTrue(!bt.isEmpty()); }