test to repro reported bug. Closes GH-3464

src/DocumentDbTests/Bugs/Bug_3464_Include_with_SingleOrDefault.cs

@@ -0,0 +1,94 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Linq.Expressions;
+using System.Threading.Tasks;
+using Marten;
+using Marten.Linq;
+using Marten.Testing.Harness;
+using Xunit;
+using Shouldly;
+
+namespace DocumentDbTests.Bugs;
+
+public class Bug_3464_Include_with_SingleOrDefault : BugIntegrationContext
+{
+    [Fact]
+    public async Task can_make_the_query()
+    {
+        StoreOptions(opts =>
+        {
+            opts.Schema.For<OrderItem>().AddSubClass<Product>()
+                .AddSubClass<Subscription>();
+        });
+
+        var product = new Product();
+        theSession.Store(product);
+
+        var user = new User3464();
+        theSession.Store(user);
+
+        var order = new Order { UserId = user.Id, OrderItemId = product.Id };
+        theSession.Store(order);
+
+        await theSession.SaveChangesAsync();
+
+        IList<Product> orderItems = [];
+        IList<User3464> users = [];
+
+        var orderId = order.Id;
+
+        var order2 = await theSession.Query<Order>()
+            .Include(o => o.OrderItemId, orderItems)
+            .Include(o => o.UserId, users)
+            .SingleOrDefaultAsync(o => o.Id == orderId);
+
+        order2.ShouldNotBeNull();
+        orderItems.Single().Id.ShouldBe(product.Id);
+        users.Single().Id.ShouldBe(user.Id);
+    }
+}
+
+public class OrderDetails : ICompiledQuery<Order, Order?>
+{
+    public Guid OrderId { get; init; }
+
+    public IList<OrderItem> OrderItems { get; } = [];
+    public IList<User3464> Users { get; } = [];
+
+    public Expression<Func<IMartenQueryable<Order>, Order?>> QueryIs()
+    {
+        return q => q
+            .Include(o => o.OrderItemId, OrderItems)
+            .Include(o => o.UserId, Users)
+            .SingleOrDefault(o => o.Id == OrderId);
+    }
+}
+
+public class Order
+{
+    public Guid Id { get; set; }
+    public Guid OrderItemId { get; set; }
+    public Guid UserId { get; set; }
+}
+
+public class User3464
+{
+    public Guid Id { get; set; }
+}
+
+public abstract class OrderItem
+{
+    public Guid Id { get; set; }
+
+}
+
+public class Product: OrderItem
+{
+
+}
+
+public class Subscription: OrderItem
+{
+
+}