Raven AsyncDocumentSession not generating Id after calling Store. [Update] In case anyone stumbles here apparently, this by design as replied in this issue: http://issues.hibernatingrhinos.com/issue/RavenDB-834

gistfile1.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using Raven.Tests.Helpers;
using Xunit;

namespace Raven.Tests
{
    public class User
    {
        public string Id { get; set; }

        public string Name { get; set; }
    }

    public class AsyncSessionTests : RavenTestBase
    {
        [Fact]
        public async Task CannotGenerateIdAfterStoreOnlyAfterSaveChanges()
        {
            using (var store = NewDocumentStore())
            {
                using (var session = store.OpenAsyncSession())
                {
                    var user = new User() {Name = "fulano"};
                    session.Store(user);
                    Assert.NotNull(user.Id);
                    await session.SaveChangesAsync();
                }

                using (var session = store.OpenAsyncSession())
                {
                    var user = await session.LoadAsync<User>(1);

                    Assert.NotNull(user);
                    Assert.Equal(user.Id, "users/1");
                }
            }
        }
    }
}