### Question:
PredicateFunction implements Function<A, Boolean> { public static <A> PredicateFunction<A> adapt(Predicate<? super A> predicate) { return null == predicate ? null : new PredicateFunction<A>(predicate); } PredicateFunction(Predicate<? super A> predicate); Boolean evaluate(A obj); @Override boolean equals(Object obj); @Override int hashCode(); @Override String toString(); static PredicateFunction<A> adapt(Predicate<? super A> predicate);  }### Answer:
@Test public void testAdaptNull() throws Exception { assertNull(PredicateFunction.adapt(null)); }
@Test public void testAdapt() throws Exception { assertNotNull(PredicateFunction.adapt(Constant.TRUE)); }