NH-3919 - Firebird fix for connection releasing, to be squashed

Author: fredericDelaporte

src/NHibernate.Test/Async/TypesTest/DateTimeTypeFixture.cs

@@ -101,6 +101,12 @@ protected override void OnTearDown()
 			}
 		}
 
+		protected override void DropSchema()
+		{
+			(Sfi.ConnectionProvider.Driver as ClientDriverWithParamsStats)?.CleanUp(); 
+			base.DropSchema();
+		}
+
 		[Test]
 		public Task DbHasExpectedTypeAsync()
 		{

src/NHibernate.Test/TypesTest/DateTimeTypeFixture.cs

@@ -121,6 +121,12 @@ protected override void OnTearDown()
 			}
 		}
 
+		protected override void DropSchema()
+		{
+			(Sfi.ConnectionProvider.Driver as ClientDriverWithParamsStats)?.CleanUp(); 
+			base.DropSchema();
+		}
+
 		[Test]
 		public void DbHasExpectedType()
 		{
@@ -290,6 +296,24 @@ DbParameter IDriver.GenerateParameter(DbCommand command, string name, SqlType sq
 			return param;
 		}
 
+		#region Firebird mess
+
+		public void CleanUp()
+		{
+			if (_driverImplementation is FirebirdClientDriver fbDriver)
+			{
+				// Firebird will pool each connection created during the test and will marked as used any table
+				// referenced by queries. It will at best delays those tables drop until connections are actually
+				// closed, or immediately fail dropping them.
+				// This results in other tests failing when they try to create tables with same name.
+				// By clearing the connection pool the tables will get dropped. This is done by the following code.
+				// Moved from NH1908 test case, contributed by Amro El-Fakharany.
+				fbDriver.ClearPool(null);
+			}
+		}
+
+		#endregion
+
 		#region Pure forwarding
 
 		void IDriver.Configure(IDictionary<string, string> settings)