### Question:
QueueByTwoStack { public Item dequeue() { return null; } QueueByTwoStack(); int size(); boolean isEmpty(); void enqueue(Item i); Item dequeue(); Item peek();  }### Answer:
@Test(expected = NoSuchElementException.class) public void basicTest5() { QueueByTwoStack<String> queue = new QueueByTwoStack(); queue.dequeue(); }