@Test public void takeUnless() { List<Integer> numberList = new ArrayList<>(Arrays.asList(1, 2, 3, 4, 5)); Predicate<Integer> positive = x -> x > 0; Collection<Integer> result = Collections.takeUnless(positive, numberList); assertEquals(emptyList(), result); assertEquals(numberList, Collections.takeUnless(IS_NULL_PREDICATE, numberList)); assertEquals(emptyList(), Collections.takeUnless(NOT_NULL_PREDICATE, numberList)); }