/// <summary>
        /// Initializes a new instance of the <see cref="SelectExpandQueryOption"/> class.
        /// </summary>
        /// <param name="select">The $select query parameter value.</param>
        /// <param name="expand">The $expand query parameter value.</param>
        /// <param name="context">The <see cref="ODataQueryContext"/> which contains the <see cref="IEdmModel"/> and some type information.</param>
        /// <param name="queryOptionParser">The <see cref="ODataQueryOptionParser"/> which is used to parse the query option.</param>
        public SelectExpandQueryOption(string select, string expand, ODataQueryContext context,
            ODataQueryOptionParser queryOptionParser)
        {
            if (context == null)
            {
                throw Error.ArgumentNull("context");
            }

            if (String.IsNullOrEmpty(select) && String.IsNullOrEmpty(expand))
            {
                throw Error.Argument(SRResources.SelectExpandEmptyOrNull);
            }

            if (queryOptionParser == null)
            {
                throw Error.ArgumentNull("queryOptionParser");
            }

            IEdmEntityType entityType = context.ElementType as IEdmEntityType;
            if (entityType == null)
            {
                throw Error.Argument("context", SRResources.SelectNonEntity, context.ElementType.ToTraceString());
            }

            Context = context;
            RawSelect = select;
            RawExpand = expand;
            Validator = new SelectExpandQueryValidator();
            _queryOptionParser = queryOptionParser;
        }
        // This constructor is intended for unit testing only.
        internal SelectExpandQueryOption(string select, string expand, ODataQueryContext context)
        {
            if (context == null)
            {
                throw Error.ArgumentNull("context");
            }

            if (String.IsNullOrEmpty(select) && String.IsNullOrEmpty(expand))
            {
                throw Error.Argument(SRResources.SelectExpandEmptyOrNull);
            }

            IEdmEntityType entityType = context.ElementType as IEdmEntityType;
            if (entityType == null)
            {
                throw Error.Argument("context", SRResources.SelectNonEntity, context.ElementType.ToTraceString());
            }

            Context = context;
            RawSelect = select;
            RawExpand = expand;
            Validator = new SelectExpandQueryValidator();
            _queryOptionParser = new ODataQueryOptionParser(
                context.Model,
                context.ElementType,
                context.NavigationSource,
                new Dictionary<string, string> { { "$select", select }, { "$expand", expand } });
        }