Creates test open reader problem

Author: alex-kulakov

Orm/Xtensive.Orm.Tests/Issues/IssueGitHub071_DataReaderRemainsOpen.cs

@@ -0,0 +1,130 @@
+// Copyright (C) 2020 Xtensive LLC.
+// This code is distributed under MIT license terms.
+// See the License.txt file in the project root for more information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using NUnit.Framework;
+using Xtensive.Orm.Configuration;
+using Xtensive.Orm.Tests.Issues.IssueGitHub071_DataReaderRemainsOpenModel;
+
+namespace Xtensive.Orm.Tests.Issues.IssueGitHub071_DataReaderRemainsOpenModel
+{
+  [HierarchyRoot]
+  [KeyGenerator(KeyGeneratorKind.None)]
+  public class Item : Entity
+  {
+    [Field, Key]
+    public Guid Id { get; private set; }
+
+    public Item(Session session, Guid id)
+      : base(session, id)
+    { }
+  }
+}
+
+namespace Xtensive.Orm.Tests.Issues
+{
+  [TestFixture]
+  public sealed class IssueGitHub071_DataReaderRemainsOpen : AutoBuildTest
+  {
+    protected override DomainConfiguration BuildConfiguration()
+    {
+      var config = base.BuildConfiguration();
+      config.Types.Register(typeof(Item));
+      return config;
+    }
+
+    [Test]
+    public void ConcatOfEmptySequencesTest1()
+    {
+      using (var session = Domain.OpenSession())
+      using (var tx = session.OpenTransaction()) {
+        var list = new List<Guid>();
+        var sequence = Enumerable.Empty<Guid>().Concat(session.Query.All<Item>()
+          .Where(item => item.Id == Guid.Empty)
+          .Select(item => item.Id));
+        foreach (var guid in sequence) {
+          list.Add(guid);
+        }
+
+        Assert.AreEqual(0, list.Count);
+        tx.Complete();
+      }
+    }
+
+    [Test]
+    public void ConcatOfEmptySequencesTest2()
+    {
+      using (var session = Domain.OpenSession())
+      using (var tx = session.OpenTransaction()) {
+        var list = new List<Guid>();
+        var sequence = session.Query.All<Item>()
+          .Where(item => item.Id == Guid.Empty)
+          .Select(item => item.Id).AsEnumerable().Concat(Enumerable.Empty<Guid>());
+        foreach (var guid in sequence) {
+          list.Add(guid);
+        }
+
+        Assert.AreEqual(0, list.Count);
+        tx.Complete();
+      }
+    }
+
+    [Test]
+    public void UnionOfEmptySequencesTest1()
+    {
+      using (var session = Domain.OpenSession())
+      using (var tx = session.OpenTransaction()) {
+        var list = new List<Guid>();
+        var sequence = Enumerable.Empty<Guid>().Union(session.Query.All<Item>()
+          .Where(item => item.Id == Guid.Empty)
+          .Select(item => item.Id));
+        foreach (var guid in sequence) {
+          list.Add(guid);
+        }
+
+        Assert.AreEqual(0, list.Count);
+        tx.Complete();
+      }
+    }
+
+    [Test]
+    public void UnionOfEmptySequencesTest2()
+    {
+      using (var session = Domain.OpenSession())
+      using (var tx = session.OpenTransaction()) {
+        var list = new List<Guid>();
+        var sequence = session.Query.All<Item>()
+          .Where(item => item.Id == Guid.Empty)
+          .Select(item => item.Id).AsEnumerable().Union(Enumerable.Empty<Guid>());
+        foreach (var guid in sequence) {
+          list.Add(guid);
+        }
+
+        Assert.AreEqual(0, list.Count);
+        tx.Complete();
+      }
+    }
+
+    [Test]
+    public void JustEmptyQueryResult()
+    {
+      using (var session = Domain.OpenSession())
+      using (var tx = session.OpenTransaction()) {
+        var list = new List<Guid>();
+        var sequence = session.Query.All<Item>()
+          .Where(item => item.Id == Guid.Empty)
+          .Select(item => item.Id);
+        foreach (var guid in sequence) {
+          list.Add(guid);
+        }
+
+        Assert.AreEqual(0, list.Count);
+        tx.Complete();
+      }
+    }
+  }
+}