### Question:
Collection extends jsimple.lang.Iterable<E> { public boolean isEmpty() { return size() == 0; } protected  Collection(); boolean add(E object); boolean addAll(Collection<? extends E> collection); void clear(); boolean contains(E object); boolean containsAll(Collection<E> collection); boolean isEmpty(); @Override abstract Iterator<E> iterator(); boolean remove(E object); boolean removeAll(Collection<E> collection); boolean retainAll(Collection<E> collection); abstract int size(); Object[] toArray(); void toArray(E[] contents); @Override String toString();  }### Answer:
@Test public void testIsEmpty() { final boolean[] sizeCalled = new boolean[1]; Collection<Object> ac = new TestIsEmptyCollection(this, sizeCalled); assertTrue(ac.isEmpty()); assertTrue(sizeCalled[0]); }