MultiMap doesn't work with NULL values

Replicated a bug 'Dapper MultiMap doesn't work with splitOn with NULL
value' reported on SO http://stackoverflow.com/q/10744728/449906.
Dapper doesn't create an instance of the class if the first property
after split is mapped to a column with NULL value.

Tests/Assert.cs

@@ -48,5 +48,12 @@ public static void IsNull(this object obj)
             }
         }
 
+        public static void IsNotNull(this object obj)
+        {
+            if (obj == null)
+            {
+                throw new ApplicationException("Expected not null");
+            }
+        }
     }
 }

Tests/Tests.cs

@@ -579,6 +579,7 @@ class Category
         {
             public int Id { get; set; }
             public string Name { get; set; }
+            public string Description { get; set; }
         }
         public void TestMultiMapWithSplit() // http://stackoverflow.com/q/6056778/23354
         {
@@ -594,6 +595,22 @@ class Category
             product.Category.Id.IsEqualTo(2);
             product.Category.Name.IsEqualTo("def");
         }
+        public void TestMultiMapWithSplitWithNullValue() // http://stackoverflow.com/q/10744728/449906
+        {
+            var sql = @"select 1 as id, 'abc' as name, NULL as description, 'def' as name";
+            var product = connection.Query<Product, Category, Product>(sql, (prod, cat) =>
+            {
+                prod.Category = cat;
+                return prod;
+            }, splitOn: "description").First();
+            // assertions
+            product.Id.IsEqualTo(1);
+            product.Name.IsEqualTo("abc");
+            product.Category.IsNotNull();
+            product.Category.Id.IsEqualTo(0);
+            product.Category.Name.IsEqualTo("def");
+            product.Category.Description.IsNull();
+        }
         public void TestFieldsAndPrivates()
         {
             var data = connection.Query<TestFieldCaseAndPrivatesEntity>(