@Test
    void testEmpty() {
        HitGroup hits = new HitGroup();
        Iterator<Hit> it = hits.deepIterator();
        assertFalse(it.hasNext());
        try {
            it.next();
            fail();
        } catch (NoSuchElementException e) {
            // regular iterator behavior
        }
    }
Ensure that the {@link DeepHitIterator} works as intended.

@author havardpe
container-search/src/test/java/com/yahoo/search/result/test/DeepHitIteratorTestCase.java