test for issue #4390

Tests/Linq/Tools/EntityServices/IdentityMapTests.cs

@@ -1,7 +1,14 @@
-using System.Linq;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading;
+using System.Threading.Tasks;
+
+using LinqToDB;
 
 using NUnit.Framework;
 
+using Tests.Linq;
+
 namespace Tests.Tools.EntityServices
 {
 	using LinqToDB.Common;
@@ -102,5 +109,19 @@ public void NegativeTest()
 				Assert.Throws<LinqToDBConvertException>(() => map.GetEntity<Person>(new { ID1 = 1 }));
 			}
 		}
+
+		[Test]
+		public async Task CompiledQueryTest()
+		{
+			await using var db  = new TestDataConnection();
+			using       var map = new IdentityMap(db);
+
+			var query = CompiledQuery.Compile<TestDataConnection,CancellationToken,Task<List<Person>>>(static (db, ct) => db.Person.Where(p => p.ID == 1).ToListAsync(ct));
+
+			var result1 = await query(db, default);
+			var result2 = await query(db, default);
+
+			Assert.That(result1[0], Is.SameAs(result2[0]));
+		}
 	}
 }

Tests/Linq/UserTests/Issue4390Tests.cs

@@ -0,0 +1,68 @@
+using System.Linq;
+
+using LinqToDB;
+using LinqToDB.Mapping;
+using NUnit.Framework;
+
+using System;
+
+using FluentAssertions;
+
+namespace Tests.UserTests
+{
+	[TestFixture]
+	public class Issue4390Tests : TestBase
+	{
+		[Table]
+		public class InfeedAdviceDTO
+		{
+			[Column] public int Id { get; set; }
+		}
+
+		[Table]
+		public class InventoryResourceDTO
+		{
+			[Column] public int InfeedAdviceID { get; set; }
+		}
+		public class MlogCombined1
+		{
+			public InfeedAdviceDTO? InfeedAdvice { get; set; }
+
+			public int? Count { get; set; }
+		}
+
+		public class MlogCombined2
+		{
+			public MlogCombined1? MlogCombined1 { get; set; }
+		}
+
+		[Test]
+		public void Issue4390Test([IncludeDataSources(TestProvName.AllSQLite)] string context)
+		{
+			using (var db = GetDataContext(context))
+			using (db.CreateLocalTable<InfeedAdviceDTO>())
+			using (db.CreateLocalTable<InventoryResourceDTO>())
+			{
+				db.Insert(new InventoryResourceDTO() { InfeedAdviceID = 1 });
+				db.Insert(new InfeedAdviceDTO() { Id = 1 });
+
+				var irs = from ir in db.GetTable<InventoryResourceDTO>() select ir;
+
+				var qry = from infeed in db.GetTable<InfeedAdviceDTO>()
+								join inventory in db.GetTable<InventoryResourceDTO>() on infeed.Id equals inventory.InfeedAdviceID
+								select new MlogCombined2
+								{
+									MlogCombined1 = new MlogCombined1
+									{
+										InfeedAdvice = infeed,
+										Count = irs.Count(x => x.InfeedAdviceID == infeed.Id),
+									}
+								};
+
+				var count = qry.Where(x => x.MlogCombined1 != null).Count();
+
+				count.Should().Be(1);
+			}
+		}
+	}
+}