NH-2176 - Additional tests and tests fixes for distributed transactions.

Author: fredericDelaporte

src/NHibernate.Test/DebugSessionFactory.cs

@@ -61,8 +61,9 @@ public bool CheckSessionsWereClosed()
 
 				if (txContext?.ShouldCloseSessionOnDistributedTransactionCompleted ?? false)
 				{
-					// Delayed transactions not having completed and closed their sessions? Give them a chance to complete.
+					// Delayed rollback not having lock from prepare phase? Give it a chance to complete.
 					Thread.Sleep(100);
+					txContext.WaitOne();
 					if (!session.IsOpen)
 					{
 						_log.Warn($"Test case had a delayed close of session {session.SessionId}.");

src/NHibernate.Test/NHSpecificTest/DtcFailures/DtcFailuresFixture.cs

@@ -49,6 +49,8 @@ protected override void CreateSchema()
 
 		protected override void OnTearDown()
 		{
+			DodgeTransactionCompletionDelayIfRequired();
+
 			using (var s = OpenSession())
 			using (var t = s.BeginTransaction())
 			{
@@ -505,11 +507,53 @@ public void CanUseSessionOutsideOfScopeAfterScope([Values(false, true)] bool exp
 				Assert.DoesNotThrow(() => count = s.Query<Person>().Count(), "Failed using the session after scope.");
 				if (count != 1)
 					// We are not testing that here, so just issue a warning. Do not use DodgeTransactionCompletionDelayIfRequired
-					// before  previous assert. We want to ascertain the session is usable in any cases.
+					// before previous assert. We want to ascertain the session is usable in any cases.
 					Assert.Warn("Unexpected entity count: {0} instead of {1}. The transaction seems to have a delayed commit.", count, 1);
 			}
 		}
 
+		[Test(Description = "Do not fail, but warn in case a delayed after scope disposal commit is made.")]
+		public void DelayedTransactionCompletion([Values(false, true)] bool explicitFlush)
+		{
+			for (var i = 1; i <= 10; i++)
+			{
+				// Isolation level must be read committed on the control session: reading twice while expecting some data insert
+				// in between due to a late commit. Repeatable read would block and read uncommitted would see the uncommitted data.
+				using (var controlSession = OpenSession())
+				using (controlSession.BeginTransaction(System.Data.IsolationLevel.ReadCommitted))
+				{
+					// We want to have the control session as ready to query as possible, thus beginning its
+					// transaction early for acquiring the connection, even if we will not use it before 
+					// below scope completion.
+
+					using (var tx = new TransactionScope())
+					{
+						using (var s = OpenSession())
+						{
+							s.Save(new Person { CreatedAt = DateTime.Today });
+
+							ForceEscalationToDistributedTx.Escalate();
+
+							if (explicitFlush)
+								s.Flush();
+						}
+						tx.Complete();
+					}
+
+					var count = controlSession.Query<Person>().Count();
+					if (count != i)
+					{
+						Thread.Sleep(100);
+						var countSecondTry = controlSession.Query<Person>().Count();
+						Assert.Warn($"Unexpected entity count: {count} instead of {i}. " +
+							"This may mean current data provider has a delayed commit, occurring after scope disposal. " +
+							$"After waiting, count is now {countSecondTry}. ");
+						break;
+					}
+				}
+			}
+		}
+
 		private void AssertNoPersons()
 		{
 			using (var s = OpenSession())