Add ability to set fetch for <one-to-one> mapping in mapping by code

Author: hazzik

src/NHibernate.Test/MappingByCode/MappersTests/OneToOneMapperTest.cs

@@ -164,5 +164,31 @@ public void WhenSetFormulaWithMultipleLinesThenSetFormulaNode()
 			Assert.That(hbmFormula.Text[1], Is.EqualTo("Line2"));
 			Assert.That(mapping.formula1, Is.Null);
 		}
+		
+		[Test]
+		public void WhenSetFetchModeToJoinThenSetFetch()
+		{
+			var member = For<MyClass>.Property(c => c.Relation);
+			var mapping = new HbmOneToOne();
+			var mapper = new OneToOneMapper(member, mapping);
+
+			mapper.Fetch(FetchKind.Join);
+
+			Assert.That(mapping.fetch, Is.EqualTo(HbmFetchMode.Join));
+			Assert.That(mapping.fetchSpecified, Is.True);
+		}
+
+		[Test]
+		public void WhenSetFetchModeToSelectThenSetFetch()
+		{
+			var member = For<MyClass>.Property(c => c.Relation);
+			var mapping = new HbmOneToOne();
+			var mapper = new OneToOneMapper(member, mapping);
+
+			mapper.Fetch(FetchKind.Select);
+
+			Assert.That(mapping.fetch, Is.EqualTo(HbmFetchMode.Select));
+			Assert.That(mapping.fetchSpecified, Is.True);
+		}
 	}
 }

src/NHibernate/Mapping/ByCode/IOneToOneMapper.cs

@@ -15,6 +15,9 @@ public interface IOneToOneMapper : IEntityPropertyMapper
 		void Formula(string formula);
 		void ForeignKey(string foreignKeyName);
 		void Class(System.Type clazz);
+
+		//6.0 TODO: Uncomment
+		//void Fetch(FetchKind fetchMode);
 	}
 
 	public interface IOneToOneMapper<T> : IOneToOneMapper
@@ -35,5 +38,11 @@ public static void Formulas(this IOneToOneMapper mapper, params string[] formula
 			var o2oMapper = ReflectHelper.CastOrThrow<OneToOneMapper>(mapper, "Setting many formula");
 			o2oMapper.Formulas(formulas);
 		}
+
+		public static void Fetch(this IOneToOneMapper mapper, FetchKind fetchMode)
+		{
+			var o2oMapper = ReflectHelper.CastOrThrow<OneToOneMapper>(mapper, "Setting fetch");
+			o2oMapper.Fetch(fetchMode);
+		}
 	}
 }

src/NHibernate/Mapping/ByCode/Impl/OneToOneMapper.cs

@@ -135,6 +135,12 @@ public void ForeignKey(string foreignKeyName)
 		}
 
 		#endregion
+
+		public void Fetch(FetchKind fetchMode)
+		{
+			_oneToOne.fetch = fetchMode.ToHbm();
+			_oneToOne.fetchSpecified = true;
+		}
 	}
 
 	public class OneToOneMapper<T> : OneToOneMapper, IOneToOneMapper<T>