NH-4058 - ignoring a test instead of providing a workaround for its failure cause.

Author: fredericDelaporte

src/NHibernate.Test/Linq/ByMethod/GroupByTests.cs

@@ -781,6 +781,8 @@ public void GroupByComputedValueInObjectArrayWithJoinInRightSideOfCase()
 				Assert.Ignore("SQL Server seems unable to match complex group by and select list arguments when running over ODBC.");
 			if (Dialect is MsSqlCeDialect)
 				Assert.Ignore("SQL Server CE does not support complex group by expressions.");
+			if (Dialect is Oracle8iDialect)
+				Assert.Ignore("ORA-12704: character set mismatch. Due to NHibernate creating Unicode string types as NVarchar2 but querying them as Varchar2.");
 
 			var orderGroups = db.OrderLines.GroupBy(o => new[] { o.Order.Customer.CustomerId == null ? "unknown" : o.Order.Customer.CompanyName }).Select(g => new { Key = g.Key, Count = g.Count() }).ToList();
 			Assert.AreEqual(2155, orderGroups.Sum(g => g.Count));

src/NHibernate.Test/TestCase.cs

@@ -292,12 +292,7 @@ protected virtual void DropSchema()
 
 		protected virtual DebugSessionFactory BuildSessionFactory()
 		{
-			var factory = new DebugSessionFactory(cfg.BuildSessionFactory());
-			// Avoid ORA-12704 in tests, due to NHibernate defaulting String to NVarchar2 when creating tables while
-			// ODP.Net defaults it to Varchar2 (which does support Unicode too, depending on server) for parameters.
-			if (factory.ActualFactory.ConnectionProvider.Driver is OracleManagedDataClientDriver oracleManagedDriver)
-				oracleManagedDriver.UseNVarchar2ForStringParameter = true;
-			return factory;
+			return new DebugSessionFactory(cfg.BuildSessionFactory());
 		}
 
 		private void Cleanup()

src/NHibernate/Driver/OracleManagedDataClientDriver.cs

@@ -23,7 +23,6 @@ public class OracleManagedDataClientDriver : ReflectionBasedDriver, IEmbeddedBat
 		private readonly object oracleDbTypeRefCursor;
 		private readonly object oracleDbTypeXmlType;
 		private readonly object oracleDbTypeBlob;
-		private readonly object _oracleDbTypeNVarchar2;
 
 		/// <summary>
 		/// Initializes a new instance of <see cref="OracleDataClientDriver"/>.
@@ -48,31 +47,8 @@ public OracleManagedDataClientDriver()
 			oracleDbTypeRefCursor = Enum.Parse(oracleDbTypeEnum, "RefCursor");
 			oracleDbTypeXmlType = Enum.Parse(oracleDbTypeEnum, "XmlType");
 			oracleDbTypeBlob = Enum.Parse(oracleDbTypeEnum, "Blob");
-			_oracleDbTypeNVarchar2 = Enum.Parse(oracleDbTypeEnum, "NVarchar2");
 		}
 
-		/// <summary>
-		/// By default, ODP.Net maps <see cref="DbType.String"/> to <c>OracleDbType.Varchar2</c>. If you need it to be mapped
-		/// to <c>OracleDbType.NVarchar2</c> instead, set this property to <see langword="true"/>.
-		/// </summary>
-		/// <remarks>
-		/// <para>
-		/// This is not a bug. Varchar2 with Oracle can be Unicode, depending on the server configuration. If the server is
-		/// configured for having it Unicode, Varchar2 should be used for Unicode string. NVarchar2 is there for allowing
-		/// storing Unicode string on server not configured for Unicode.
-		/// http://docs.oracle.com/cd/E51173_01/win.122/e17732/featOraCommand.htm#i1007432
-		/// </para>
-		/// <para>
-		/// So the default NHibernate choice in Oracle dialects to map <see cref="DbType.String"/> to <c>nvarchar2</c> is a bit
-		/// unfortunate, because this is not the default mapping for Oracle. For tests, since the database is created by NHibernate,
-		/// string columns get typed <c>nvarchar2</c>, but parameters are still typed <c>varchar2</c>, causing an
-		/// <c>ORA-12704: character set mismatch</c> for some queries. This being not even reported, I guess most NHibernate Oracle
-		/// users handles their tables themselves and types them with <c>varchar2</c>, avoiding the trouble. So changing the behavior
-		/// for parameters type would be a major breaking change.
-		/// </para>
-		/// </remarks>
-		public bool UseNVarchar2ForStringParameter { get; set; }
-
 		/// <summary></summary>
 		public override string NamedPrefix
 		{
@@ -113,12 +89,6 @@ protected override void InitializeParameter(DbParameter dbParam, string name, Sq
 				case DbType.Binary:
 					InitializeParameter(dbParam, name, oracleDbTypeBlob);
 					break;
-				case DbType.String:
-					if (UseNVarchar2ForStringParameter)
-						InitializeParameter(dbParam, name, _oracleDbTypeNVarchar2);
-					else
-						base.InitializeParameter(dbParam, name, sqlType);
-					break;
 				default:
 					base.InitializeParameter(dbParam, name, sqlType);
 					break;