@Test
    void isParallel() {
        assertFalse(instance.isParallel());
        final Stream<String> newStream = instance.parallel();
        assertTrue(newStream.isParallel());
    }
Test of mapToInt method, of class SingletonStream.
common-parent/singletonstream/src/test/java/com/speedment/common/singletonstream/SingletonStreamTest.java