public void upperCase_returns_upper()
        {
            var cat = new CommaUpperCat("cat,in,hat");

            cat.Kittens.Should().BeEquivalentTo(new[] { "CAT", "IN", "HAT" });
        }
        public void Null_converts_to_empty_array()
        {
            var cat3 = new CommaUpperCat((string)null);

            cat3.Kittens.Should().BeEquivalentTo(new string[0]);
        }
        public void empty_string_returns_empty_array()
        {
            var cat = new CommaUpperCat("");

            cat.Kittens.Should().BeEquivalentTo(new string[0]);
        }