/// <summary>
        /// Serialize query results as collection of elements of type <typeparamref name="T"/>
        /// </summary>
        /// <typeparam name="T"></typeparam>
        /// <returns>Query result</returns>
        public IEnumerable <T> As <T>() where T : class
        {
            var p = _a.Promise <IEnumerable <T> >();

            if (p is Containing <IEnumerable <T> > c)
            {
                return(c.Get(Sql.Hash(), _description));
            }

            IEnumerable <T> result;
            var             cq = _runtime.Tooling.Compile(Sql);

            try
            {
                using (var t = _a.GetQueryTransaction())
                {
                    result = _runtime.DoQuery <T>(cq.Query, cq.Parameters);
                    if (p is NotifyCompleted <IEnumerable <T> > nc)
                    {
                        nc.Fulfill($"{_description}. {cq.Query}");
                    }
                    t.Commit();
                }
            }
            catch (Exception ex)
            {
                if (p is Catching <IEnumerable <T> > de)
                {
                    de.Fulfill(ex, $"{_description}. {cq.Query}");
                }
                throw;
            }

            if (p is Demanding <IEnumerable <T> > d)
            {
                d.Fulfill(result, Sql.Hash(), _description);
            }

            return(result);
        }
        public T Test <T>(T instance) where T : struct
        {
            var p = _testingContext.Promise <T>();

            return(p.ResolveValue(() => instance, () => $"Test_{_order++}"));
        }