@Test
    void iteratorNext() {
        final AtomicInteger cnt = new AtomicInteger();
        final Iterator<String> iterator = instance.iterator();
        while (iterator.hasNext()) {
            String element = iterator.next();
            cnt.incrementAndGet();
        }
        assertEquals(1, cnt.get());
    }
Test of mapToInt method, of class SingletonStream.
common-parent/singletonstream/src/test/java/com/speedment/common/singletonstream/SingletonStreamTest.java