### Question:
IntSinglyLinkedList implements Serializable, Iterable<Integer> { public int size() { return size; } IntSinglyLinkedList(); int size(); boolean contains(int item); void addLast(int item); void addFirst(int item); boolean isEmpty(); void clear(); int pop(); int peek(); void push(int item); int dequeue(); int getFirst(); void enqueue(int item); int[] toArray(); Integer[] toObjArray(); @Override String toString(); @Override boolean equals(Object other); @Override int hashCode(); @Override IntListIterator iterator();  }### Answer:
@Test public void testSize() { IntSinglyLinkedList list = new IntSinglyLinkedList(); int size = 5; for(int i = 0; i < size; i++) { list.enqueue(i); } assertEquals(size, list.size()); }
@Test public void testSizeEmptyList() { IntSinglyLinkedList list = new IntSinglyLinkedList(); assertEquals(0, list.size()); }