public void DistinctWithComparer()
        {
            DataProducer <string>  subject = new DataProducer <string>();
            IDataProducer <string> result  = subject.Distinct(StringComparer.OrdinalIgnoreCase);

            ProduceAndCheck(subject, result,
                            new[] { "zero", "one", "two", "one", "TWO", "three" },
                            new[] { "zero", "one", "two", "three" });
        }