diff --git a/mass_mailing_unique/README.rst b/mass_mailing_unique/README.rst
index 22ddc251..e75c471b 100644
--- a/mass_mailing_unique/README.rst
+++ b/mass_mailing_unique/README.rst
@@ -47,6 +47,7 @@ Contributors
 
 * Jairo Llopis <jairo.llopis@tecnativa.com>
 * Vicent Cubells <vicent.cubells@tecnativa.com>
+* Pedro M. Baeza <pedro.baeza@tecnativa.com>
 
 Maintainer
 ----------
diff --git a/mass_mailing_unique/tests/__init__.py b/mass_mailing_unique/tests/__init__.py
new file mode 100644
index 00000000..e876756a
--- /dev/null
+++ b/mass_mailing_unique/tests/__init__.py
@@ -0,0 +1,4 @@
+# -*- coding: utf-8 -*-
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+from . import test_mass_mailing_unique
diff --git a/mass_mailing_unique/tests/test_mass_mailing_unique.py b/mass_mailing_unique/tests/test_mass_mailing_unique.py
new file mode 100644
index 00000000..0e962fd1
--- /dev/null
+++ b/mass_mailing_unique/tests/test_mass_mailing_unique.py
@@ -0,0 +1,45 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 Tecnativa - Pedro M. Baeza
+# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl.html).
+
+from openerp.tests import common
+from openerp import exceptions
+from ..hooks import pre_init_hook
+
+
+class TestMassMailingUnique(common.SavepointCase):
+    @classmethod
+    def setUpClass(cls):
+        super(TestMassMailingUnique, cls).setUpClass()
+        cls.list = cls.env['mail.mass_mailing.list'].create({
+            'name': 'Test list',
+        })
+        cls.contact1 = cls.env['mail.mass_mailing.contact'].create({
+            'name': 'Contact 1',
+            'email': 'email1@test.com',
+        })
+
+    def test_init_hook_list(self):
+        # Disable temporarily the constraint
+        self.env.cr.execute("""
+            ALTER TABLE mail_mass_mailing_list
+            DROP CONSTRAINT mail_mass_mailing_list_unique_name
+            """)
+        self.env['mail.mass_mailing.list'].create({
+            'name': 'Test list',
+        })
+        with self.assertRaises(exceptions.ValidationError):
+            pre_init_hook(self.env.cr)
+
+    def test_init_hook_contact(self):
+        # Disable temporarily the constraint
+        self.env.cr.execute("""
+            ALTER TABLE mail_mass_mailing_contact
+            DROP CONSTRAINT mail_mass_mailing_contact_unique_mail_per_list
+            """)
+        self.env['mail.mass_mailing.contact'].create({
+            'name': 'Contact 2',
+            'email': 'email1@test.com',
+        })
+        with self.assertRaises(exceptions.ValidationError):
+            pre_init_hook(self.env.cr)