@Test
    void spliteratorEstimateSize() {
        final AtomicInteger cnt = new AtomicInteger();
        final Spliterator<String> spliterator = instance.spliterator();
        assertEquals(1, spliterator.estimateSize());
        spliterator.tryAdvance(e -> cnt.incrementAndGet());
        assertEquals(0, spliterator.estimateSize());
        assertEquals(1, cnt.get());
    }
Test of mapToInt method, of class SingletonStream.
common-parent/singletonstream/src/test/java/com/speedment/common/singletonstream/SingletonStreamTest.java