public void Filter_NullArray_ArgumentNullException()
        {
            IEnumerable <int> numbers   = null;
            IntPredicate      predicate = new IntPredicate(7);

            Assert.Throws <ArgumentNullException>(() => numbers.Filter(x => predicate.IsMatch(x)));
        }
        public IEnumerable <int> Filter_IsCorrect_IntValue(IEnumerable <int> numbers, int filter)
        {
            IntPredicate predicate = new IntPredicate(filter);

            return(numbers.Filter(x => predicate.IsMatch(x)));
        }