### Question:
IsElementOf implements BinaryPredicate<L, R> { public static IsElementOf<Object, Object> instance() { return INSTANCE; } IsElementOf(); boolean test(L obj, R col); @Override boolean equals(Object obj); @Override int hashCode(); @Override String toString(); static IsElementOf<Object, Object> instance(); static Predicate<A> instance(Object obj);  }### Answer:
@Test public void testWrapNull() { try { IsElementOf.instance(null); fail("expected NullPointerException"); } catch (NullPointerException e) { } }
@Test public void testWrapNonCollection() { try { IsElementOf.instance(Integer.valueOf(3)); fail("expected IllegalArgumentException"); } catch (IllegalArgumentException e) { } }