Fix dirty checking when property's previous state is uninitialized (NH-2860)

Author: hazzik

src/NHibernate.Test/NHSpecificTest/NH2860/ClassA.cs

@@ -0,0 +1,9 @@
+namespace NHibernate.Test.NHSpecificTest.NH2860
+{
+	public class ClassA
+	{
+		public virtual int ID{ get; set; }
+		public virtual string Text { get; set; }
+		public virtual byte[] Blob_Field { get; set; }
+	}
+}

src/NHibernate.Test/NHSpecificTest/NH2860/Mappings.hbm.xml

@@ -0,0 +1,15 @@
+<?xml version="1.0" encoding="utf-8" ?>
+
+<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernate.Test" namespace="NHibernate.Test.NHSpecificTest.NH2860">
+
+  <class name="ClassA" table="A" lazy="true" dynamic-update="true" polymorphism="explicit">
+    <id name="ID" column="ID" type="int" unsaved-value="0">
+      <generator class="native" >
+        <param name="sequence">gen_a_id</param>
+      </generator>
+    </id>
+    <property name="Text" column="TEXT" type="string" length="200" not-null="false"/>
+    <property name="Blob_Field" column="BLOB_FIELD" type="BinaryBlob" not-null="false" lazy="true"/>
+
+  </class>
+</hibernate-mapping>

src/NHibernate.Test/NHSpecificTest/NH2860/SampleTest.cs

@@ -0,0 +1,87 @@
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.NH2860
+{
+	[TestFixture]
+	public class SampleTest : BugTestCase
+	{
+		private int objId;
+
+		protected override void OnSetUp()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				var obj = new ClassA();
+				obj.Text = "Test existing object";
+				obj.Blob_Field = new byte[] { 0, 0, 1, 1, 2, 2 };
+				objId = (int) session.Save(obj);
+				transaction.Commit();
+			}
+		}
+
+		protected override void OnTearDown()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+				session.Delete("from ClassA");
+				transaction.Commit();
+			}
+		}
+
+		[Test]
+		public void Can_LazyPropertyCastingException()
+		{
+			//following causes exception "Unable to cast object of type 'System.Object' to type 'System.Byte[]'.
+			//notice that ClassA.Blob_Field s declared as lazy property
+			//similar to fixed NH-2510 (?)
+			//PS. Exception is beeing thrown only if object was created within the same session
+
+			using (var session = OpenSession())
+			{
+				var classA = new ClassA();
+				classA.Text = "new entity";
+				classA.Blob_Field = new byte[] { 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 };
+				using (var trans = session.BeginTransaction())
+				{
+					session.Save(classA);
+					trans.Commit();
+				}
+
+				session.Refresh(classA);
+
+				classA.Text = "updated entity";
+				using (var trans = session.BeginTransaction())
+				{
+					session.SaveOrUpdate(classA);
+					trans.Commit();
+				}
+
+				session.Refresh(classA);
+			}
+		}
+
+		[Test]
+		public void Can_LazyPropertyNotCastingException()
+		{
+			//here none exception beeing thrown
+			using (var session = OpenSession())
+			{
+				var classA = session.Get<ClassA>(objId);
+				Assert.IsNotNull(classA);
+
+				session.Refresh(classA);
+
+				classA.Text = "updated entity";
+				using (var trans = session.BeginTransaction())
+				{
+					session.SaveOrUpdate(classA);
+					trans.Commit();
+				}
+
+				session.Refresh(classA);
+			}
+		}
+	}
+}

src/NHibernate.Test/NHibernate.Test.csproj

@@ -1007,6 +1007,8 @@
     <Compile Include="NHSpecificTest\NH3016\Fixture.cs" />
     <Compile Include="NHSpecificTest\NH3145\Fixture.cs" />
     <Compile Include="NHSpecificTest\NH3145\Model.cs" />
+    <Compile Include="NHSpecificTest\NH2860\ClassA.cs" />
+    <Compile Include="NHSpecificTest\NH2860\SampleTest.cs" />
     <Compile Include="NHSpecificTest\Properties\CompositePropertyRefTest.cs" />
     <Compile Include="NHSpecificTest\Properties\DynamicEntityTest.cs" />
     <Compile Include="NHSpecificTest\Properties\Model.cs" />
@@ -2857,6 +2859,7 @@
     <EmbeddedResource Include="NHSpecificTest\NH1291AnonExample\Mappings.hbm.xml" />
   </ItemGroup>
   <ItemGroup>
+    <EmbeddedResource Include="NHSpecificTest\NH2860\Mappings.hbm.xml" />
     <EmbeddedResource Include="NHSpecificTest\NH3332\Mappings.hbm.xml" />
     <EmbeddedResource Include="NHSpecificTest\NH3050\Mappings.hbm.xml" />
     <EmbeddedResource Include="NHSpecificTest\NH2651\Mappings.hbm.xml" />

src/NHibernate/Type/TypeHelper.cs

@@ -238,11 +238,7 @@ public static int[] FindDirty(StandardProperty[] properties,
 
 			for (int i = 0; i < span; i++)
 			{
-				bool dirty =
-					!Equals(LazyPropertyInitializer.UnfetchedProperty, currentState[i]) &&
-					properties[i].IsDirtyCheckable(anyUninitializedProperties)
-					&& properties[i].Type.IsDirty(previousState[i], currentState[i], includeColumns[i], session);
-
+				var dirty = Dirty(properties, currentState, previousState, includeColumns, anyUninitializedProperties, session, i);
 				if (dirty)
 				{
 					if (results == null)
@@ -264,6 +260,16 @@ public static int[] FindDirty(StandardProperty[] properties,
 			}
 		}
 
+		private static bool Dirty(StandardProperty[] properties, object[] currentState, object[] previousState, bool[][] includeColumns, bool anyUninitializedProperties, ISessionImplementor session, int i)
+		{
+			if (Equals(LazyPropertyInitializer.UnfetchedProperty, currentState[i]))
+				return false;
+			if (Equals(LazyPropertyInitializer.UnfetchedProperty, previousState[i]))
+				return true;
+			return properties[i].IsDirtyCheckable(anyUninitializedProperties) &&
+				   properties[i].Type.IsDirty(previousState[i], currentState[i], includeColumns[i], session);
+		}
+
 		/// <summary>
 		/// <para>Determine if any of the given field values are modified, returning an array containing
 	 	/// indices of the modified fields.</para>