public static void IncludeGroupExpr()
        {
            var expr = GroupExpr.Include("one", "two");

            expr.Should().NotBeNull();
            expr.IsMatch("one").Should().BeTrue();
            expr.IsMatch("two").Should().BeTrue();
            expr.IsMatch("three").Should().BeFalse();
            expr.IsMatch(string.Empty).Should().BeFalse();
            ((Action)(() => expr.IsMatch(null))).ShouldThrow <ArgumentNullException>();
        }
        public static void IncludeGroupExpr_EmptyList()
        {
            Action action = () => GroupExpr.Include();

            action.ShouldThrow <ArgumentNullException>();
        }