### Question:
Objects { public static Mapper<Object, String> toStringValue() { return new Mapper<Object, String>() { @Override public String map(Object input) { return input.toString(); } }; }  static boolean isNull(Object value); static boolean isNotNull(Object value); static UnaryPredicate<Object> whereNull(); static UnaryPredicate<Object> whereNotNull(); static Mapper<Object, String> toStringValue(); static Mapper<T, String> toStringValueFor(@SuppressWarnings("unused") Class<T> targetClass);  }### Answer:
@Test public void returnsMapperToStringValue() { Object value = new Object() { @Override public String toString() { return "some custom toString"; } }; String result = Objects.toStringValue().map(value); assertThat(result, is("some custom toString")); }
@Test(expected = NullPointerException.class) public void throwsNullPointerExceptionWhenNullPassedToToStringValue() { Object value = null; Objects.toStringValue().map(value); }