public void is_a_test_input()
        {
            var converter = new ObjectConverter();
            var library = new FixtureLibrary(converter);

            library.IsTestVariable(typeof(Address)).ShouldBeFalse();
            library.IsTestVariable(typeof(ITestContext)).ShouldBeFalse();
            library.IsTestVariable(typeof(int?)).ShouldBeTrue();
            library.IsTestVariable(typeof(int)).ShouldBeTrue();
            library.IsTestVariable(typeof(DateTime)).ShouldBeTrue();
            library.IsTestVariable(typeof(DateTime?)).ShouldBeTrue();
        }
        public GrammarStructure ToStructure(FixtureLibrary library)
        {
            Cell[] cells = InnerGrammar.GetCells()
                .Where(x => library.IsTestVariable(x.Type))
                .Select(c => c.ToInputCell()).ToArray();

            return new Table(LabelName, LeafName(), cells);
        }