Throw for LINQ queries on unmapped entities

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

@@ -13,16 +13,45 @@
 using System.Collections.Generic;
 using System.Linq;
 using NHibernate.DomainModel.Northwind.Entities;
+using NHibernate.Hql.Ast.ANTLR;
+using NHibernate.Linq;
 using NSubstitute;
 using NUnit.Framework;
-using NHibernate.Linq;
 
 namespace NHibernate.Test.Linq
 {
 	using System.Threading.Tasks;
 	[TestFixture]
 	public class LinqQuerySamplesAsync : LinqTestCase
 	{
+		class NotMappedEntity
+		{
+			public virtual int Id { get; set; }
+			public virtual string Name { get; set; }
+		}
+
+		[Test]
+		public void ShouldThrowForQueryOnNotMappedEntityAsync()
+		{
+			var querySyntaxException = Assert.ThrowsAsync<QuerySyntaxException>(() => session.Query<NotMappedEntity>().Select(x => x.Id).ToListAsync());
+			Assert.That(querySyntaxException.Message, Does.Contain(nameof(NotMappedEntity)));
+		}
+
+		[Test]
+		public void ShouldThrowForQueryOnNotMappedEntityNameAsync()
+		{
+			var entityName = "NotMappedEntityName";
+			var querySyntaxException = Assert.ThrowsAsync<QuerySyntaxException>(() => session.Query<NotMappedEntity>(entityName).ToListAsync());
+			Assert.That(querySyntaxException.Message, Does.Contain(entityName));
+		}
+
+		[Test]
+		public void ShouldThrowForDmlQueryOnNotMappedEntityAsync()
+		{
+			var querySyntaxException = Assert.ThrowsAsync<QuerySyntaxException>(() => session.Query<NotMappedEntity>().DeleteAsync());
+			Assert.That(querySyntaxException.Message, Does.Contain(nameof(NotMappedEntity)));
+		}
+
 		[Test]
 		public async Task GroupTwoQueriesAndSumAsync()
 		{

src/NHibernate.Test/Linq/LinqQuerySamples.cs

@@ -3,6 +3,8 @@
 using System.Collections.Generic;
 using System.Linq;
 using NHibernate.DomainModel.Northwind.Entities;
+using NHibernate.Hql.Ast.ANTLR;
+using NHibernate.Linq;
 using NSubstitute;
 using NUnit.Framework;
 
@@ -11,6 +13,34 @@ namespace NHibernate.Test.Linq
 	[TestFixture]
 	public class LinqQuerySamples : LinqTestCase
 	{
+		class NotMappedEntity
+		{
+			public virtual int Id { get; set; }
+			public virtual string Name { get; set; }
+		}
+
+		[Test]
+		public void ShouldThrowForQueryOnNotMappedEntity()
+		{
+			var querySyntaxException = Assert.Throws<QuerySyntaxException>(() => session.Query<NotMappedEntity>().Select(x => x.Id).ToList());
+			Assert.That(querySyntaxException.Message, Does.Contain(nameof(NotMappedEntity)));
+		}
+
+		[Test]
+		public void ShouldThrowForQueryOnNotMappedEntityName()
+		{
+			var entityName = "NotMappedEntityName";
+			var querySyntaxException = Assert.Throws<QuerySyntaxException>(() => session.Query<NotMappedEntity>(entityName).ToList());
+			Assert.That(querySyntaxException.Message, Does.Contain(entityName));
+		}
+
+		[Test]
+		public void ShouldThrowForDmlQueryOnNotMappedEntity()
+		{
+			var querySyntaxException = Assert.Throws<QuerySyntaxException>(() => session.Query<NotMappedEntity>().Delete());
+			Assert.That(querySyntaxException.Message, Does.Contain(nameof(NotMappedEntity)));
+		}
+
 		[Test]
 		public void GroupTwoQueriesAndSum()
 		{

src/NHibernate/Hql/Ast/ANTLR/AstPolymorphicProcessor.cs

@@ -9,7 +9,7 @@ public class AstPolymorphicProcessor
     {
         private readonly IASTNode _ast;
         private readonly ISessionFactoryImplementor _factory;
-        private IEnumerable<KeyValuePair<IASTNode, IASTNode[]>> _nodeMapping;
+        private Dictionary<IASTNode, IASTNode[]> _nodeMapping;
 
         private AstPolymorphicProcessor(IASTNode ast, ISessionFactoryImplementor factory)
         {
@@ -29,8 +29,11 @@ private IASTNode[] Process()
             // Find all the polymorphic query sources
             _nodeMapping = new PolymorphicQuerySourceDetector(_factory).Process(_ast);
 
-            if (_nodeMapping.Count() > 0)
+            if (_nodeMapping.Count > 0)
             {
+                foreach (var kv in _nodeMapping.Where(x => x.Value.Length == 0))
+                    throw new QuerySyntaxException(kv.Key + " is not mapped");
+
                 return DuplicateTree().ToArray();
             }
             else
@@ -72,4 +75,4 @@ private static IASTNode DuplicateTree(IASTNode ast, IDictionary<IASTNode, IASTNo
             return dup;
         }
     }
-}
+}