diff --git a/test/test_DiffDatabaseMapping.py b/test/test_DiffDatabaseMapping.py
new file mode 100644
index 00000000..293da5b4
--- /dev/null
+++ b/test/test_DiffDatabaseMapping.py
@@ -0,0 +1,76 @@
+######################################################################################################################
+# Copyright (C) 2017 - 2018 Spine project consortium
+# This file is part of Spine Toolbox.
+# Spine Toolbox is free software: you can redistribute it and/or modify it under the terms of the GNU Lesser General
+# Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option)
+# any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
+# without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
+# Public License for more details. You should have received a copy of the GNU Lesser General Public License along with
+# this program. If not, see <http://www.gnu.org/licenses/>.
+######################################################################################################################
+
+"""
+Unit tests for DiffDatabaseMapping class.
+
+:author: P. Vennström (VTT)
+:date:   29.11.2018
+"""
+#import sys
+#sys.path.append('/spinedatabase_api')
+
+from spinedatabase_api.diff_database_mapping import DiffDatabaseMapping
+from spinedatabase_api.helpers import create_new_spine_database
+import unittest
+from sqlalchemy.orm import Session
+
+class TestDiffDatabaseMapping(unittest.TestCase):
+
+    def setUp(self):
+        """Overridden method. Runs before each test.
+        Create a empty in memory database
+        """
+
+        # create a in memory database
+        input_db = create_new_spine_database('sqlite://')
+        self.db_map = DiffDatabaseMapping("", username='IntegrationTest', create_all=False)
+        self.db_map.engine = input_db
+        self.db_map.engine.connect()
+        
+        #empty database from items
+        self.db_map.engine.execute("DELETE FROM object_class")
+        self.db_map.engine.execute("DELETE FROM object")
+        self.db_map.engine.execute("DELETE FROM relationship_class")
+        self.db_map.engine.execute("DELETE FROM relationship")
+        self.db_map.engine.execute("DELETE FROM parameter")
+        self.db_map.engine.execute("DELETE FROM parameter_value")
+        self.db_map.engine.execute("DELETE FROM [commit]")
+        
+        # initialize diff db
+        self.db_map.session = Session(self.db_map.engine, autoflush=False)
+        self.db_map.create_mapping()
+        self.db_map.create_diff_tables_and_mapping()
+        self.db_map.init_next_id()
+
+
+    def tearDown(self):
+        """Overridden method. Runs after each test.
+        Use this to free resources after a test if needed.
+        """
+        # close database connection
+        self.db_map.close()
+    
+    def test_insert_many_objects_and_commiting(self):
+        """Tests inserting many objects into db"""
+        c_id = self.db_map.add_object_classes(*[{'name': 'testclass'}]).all()[0].id
+        self.db_map.add_objects(*[{'name': str(i), 'class_id': c_id} for i in range(1001)])
+        self.db_map.commit_session('test_commit')
+        self.assertEqual(len(self.db_map.session.query(self.db_map.Object).all()), 1001)
+    
+    def test_insert_and_retrive_many_objects(self):
+        """Tests inserting many objects into db and retriving them."""
+        c_id = self.db_map.add_object_classes(*[{'name': 'testclass'}]).all()[0].id
+        objects = self.db_map.add_objects(*[{'name': str(i), 'class_id': c_id} for i in range(1001)])
+        self.assertEqual(len(objects.all()), 1001)
+
+if __name__ == '__main__':
+    unittest.main()