fixup! Support evaluation of Guid.NewGuid() on db side

Add an option for failing or falling back in case of lack of dialect
support

Author: fredericDelaporte

src/NHibernate.Test/Async/Linq/PreEvaluationTests.cs

@@ -43,40 +43,6 @@ protected override void Configure(Configuration configuration)
 			configuration.SetProperty(Environment.LinqToHqlFallbackOnPreEvaluation, FallbackOnPreEvaluation.ToString());
 		}
 
-		[Test]
-		public async Task CanQueryByNewGuidAsync()
-		{
-			if (!TestDialect.SupportsSqlType(SqlTypeFactory.Guid))
-				Assert.Ignore("Guid are not supported by the target database");
-
-			using (var spy = new SqlLogSpy())
-			{
-				var guid = Guid.NewGuid();
-				var x = await (db.Orders.CountAsync(o => guid != Guid.NewGuid()));
-
-				Assert.That(x, Is.GreaterThan(0));
-				AssertFunctionInSql("new_uuid", spy);
-			}
-		}
-
-		[Test]
-		public async Task CanSelectNewGuidAsync()
-		{
-			if (!TestDialect.SupportsSqlType(SqlTypeFactory.Guid))
-				Assert.Ignore("Guid are not supported by the target database");
-
-			using (var spy = new SqlLogSpy())
-			{
-				var x =
-					await (db
-						.Orders.Select(o => new { id = o.OrderId, g = Guid.NewGuid() })
-						.OrderBy(o => o.id).Take(1).ToListAsync());
-
-				Assert.That(x, Has.Count.GreaterThan(0));
-				AssertFunctionInSql("new_uuid", spy);
-			}
-		}
-
 		[Test]
 		public async Task CanQueryByRandomDoubleAsync()
 		{

src/NHibernate.Test/Linq/PreEvaluationTests.cs

@@ -216,14 +216,17 @@ public void CanQueryByNewGuid()
 			if (!TestDialect.SupportsSqlType(SqlTypeFactory.Guid))
 				Assert.Ignore("Guid are not supported by the target database");
 
-			using (var spy = new SqlLogSpy())
-			{
-				var guid = Guid.NewGuid();
-				var x = db.Orders.Count(o => guid != Guid.NewGuid());
+			var isSupported = IsFunctionSupported("new_uuid");
+			RunTest(
+				isSupported,
+				spy =>
+				{
+					var guid = Guid.NewGuid();
+					var x = db.Orders.Count(o => guid != Guid.NewGuid());
 
-				Assert.That(x, Is.GreaterThan(0));
-				AssertFunctionInSql("new_uuid", spy);
-			}
+					Assert.That(x, Is.GreaterThan(0));
+					AssertFunctionInSql("new_uuid", spy);
+				});
 		}
 
 		[Test]
@@ -232,16 +235,19 @@ public void CanSelectNewGuid()
 			if (!TestDialect.SupportsSqlType(SqlTypeFactory.Guid))
 				Assert.Ignore("Guid are not supported by the target database");
 
-			using (var spy = new SqlLogSpy())
-			{
-				var x =
-					db
-						.Orders.Select(o => new { id = o.OrderId, g = Guid.NewGuid() })
-						.OrderBy(o => o.id).Take(1).ToList();
+			var isSupported = IsFunctionSupported("new_uuid");
+			RunTest(
+				isSupported,
+				spy =>
+				{
+					var x =
+						db
+							.Orders.Select(o => new { id = o.OrderId, g = Guid.NewGuid() })
+							.OrderBy(o => o.id).Take(1).ToList();
 
-				Assert.That(x, Has.Count.GreaterThan(0));
-				AssertFunctionInSql("new_uuid", spy);
-			}
+					Assert.That(x, Has.Count.GreaterThan(0));
+					AssertFunctionInSql("new_uuid", spy);
+				});
 		}
 
 		[Test]

src/NHibernate/Linq/Functions/NewGuidHqlGenerator.cs

@@ -6,6 +6,7 @@
 using NHibernate.Hql.Ast;
 using NHibernate.Linq.Visitors;
 using NHibernate.Util;
+using Environment = NHibernate.Cfg.Environment;
 
 namespace NHibernate.Linq.Functions
 {
@@ -31,8 +32,17 @@ public override HqlTreeNode BuildHql(
 
 		public bool AllowPreEvaluation(MemberInfo member, ISessionFactoryImplementor factory)
 		{
-			// When not supported, allow pre-evaluation on client side as a fallback.
-			return !factory.Dialect.Functions.ContainsKey("new_uuid");
+			if (factory.Dialect.Functions.ContainsKey("new_uuid"))
+				return false;
+
+			if (factory.Settings.LinqToHqlFallbackOnPreEvaluation)
+				return true;
+
+			throw new QueryException(
+				"Cannot translate NewGuid: new_uuid is " +
+				$"not supported by {factory.Dialect}. Either enable the fallback on pre-evaluation " +
+				$"({Environment.LinqToHqlFallbackOnPreEvaluation}) or evaluate NewGuid " +
+				"outside of the query.");
 		}
 
 		public bool IgnoreInstance(MemberInfo member)