public SingleFieldSelectorTests()
        {
            theMapping = DocumentMapping.For <User>();
            var prop = ReflectionHelper.GetProperty <User>(x => x.FirstName);

            theSelector = new SingleFieldSelector <string>(theMapping, new MemberInfo[] { prop });
        }
        public SingleFieldSelectorTests()
        {
            theMapping = DocumentMapping.For<User>();
            var prop = ReflectionHelper.GetProperty<User>(x => x.FirstName);

            theSelector = new SingleFieldSelector<string>(theMapping, new MemberInfo[] {prop});
        }