diff --git a/nova/tests/test_db_api.py b/nova/tests/test_db_api.py
index 19337855..79005d10 100644
--- a/nova/tests/test_db_api.py
+++ b/nova/tests/test_db_api.py
@@ -45,9 +45,45 @@ class DbApiTestCase(test.TestCase):
 
     def create_instances_with_args(self, **kwargs):
         args = {'reservation_id': 'a', 'image_ref': 1, 'host': 'host1',
-                'project_id': self.project_id}
+                'project_id': self.project_id, 'vm_state': 'fake'}
+        if 'context' in kwargs:
+            ctxt = kwargs.pop('context')
+            args['project_id'] = ctxt.project_id
+        else:
+            ctxt = self.context
         args.update(kwargs)
-        return db.instance_create(self.context, args)
+        return db.instance_create(ctxt, args)
+
+    def test_create_instance_unique_hostname(self):
+        otherprojectcontext = context.RequestContext(self.user_id,
+                                          "%s2" % self.project_id)
+
+        self.create_instances_with_args(hostname='fake_name')
+
+        # With scope 'global' any duplicate should fail, be it this project:
+        self.flags(osapi_compute_unique_server_name_scope='global')
+        self.assertRaises(exception.InstanceExists,
+                          self.create_instances_with_args,
+                          hostname='fake_name')
+
+        # or another:
+        self.assertRaises(exception.InstanceExists,
+                          self.create_instances_with_args,
+                          context=otherprojectcontext,
+                          hostname='fake_name')
+
+        # With scope 'project' a duplicate in the project should fail:
+        self.flags(osapi_compute_unique_server_name_scope='project')
+        self.assertRaises(exception.InstanceExists,
+                          self.create_instances_with_args,
+                          hostname='fake_name')
+
+        # With scope 'project' a duplicate in a different project should work:
+        self.flags(osapi_compute_unique_server_name_scope='project')
+        self.create_instances_with_args(context=otherprojectcontext,
+                                        hostname='fake_name')
+
+        self.flags(osapi_compute_unique_server_name_scope=None)
 
     def test_ec2_ids_not_found_are_printable(self):
         def check_exc_format(method):
@@ -291,6 +327,56 @@ class DbApiTestCase(test.TestCase):
         self.assertEqual(instance['instance_type']['name'],
                 inst_type2['name'])
 
+    def test_instance_update_unique_name(self):
+        otherprojectcontext = context.RequestContext(self.user_id,
+                                          "%s2" % self.project_id)
+
+        inst = self.create_instances_with_args(hostname='fake_name')
+        uuid1p1 = inst['uuid']
+        inst = self.create_instances_with_args(hostname='fake_name2')
+        uuid2p1 = inst['uuid']
+
+        inst = self.create_instances_with_args(context=otherprojectcontext,
+                                               hostname='fake_name3')
+        uuid1p2 = inst['uuid']
+
+        # osapi_compute_unique_server_name_scope is unset so this should work:
+        values = {'hostname': 'fake_name2'}
+        db.instance_update(self.context, uuid1p1, values)
+        values = {'hostname': 'fake_name'}
+        db.instance_update(self.context, uuid1p1, values)
+
+        # With scope 'global' any duplicate should fail.
+        self.flags(osapi_compute_unique_server_name_scope='global')
+        self.assertRaises(exception.InstanceExists,
+                          db.instance_update,
+                          self.context,
+                          uuid2p1,
+                          values)
+
+        self.assertRaises(exception.InstanceExists,
+                          db.instance_update,
+                          otherprojectcontext,
+                          uuid1p2,
+                          values)
+
+        # But we should definitely be able to update our name if we aren't
+        #  really changing it.
+        case_only_values = {'hostname': 'fake_NAME'}
+        db.instance_update(self.context, uuid1p1, case_only_values)
+
+        # With scope 'project' a duplicate in the project should fail:
+        self.flags(osapi_compute_unique_server_name_scope='project')
+        self.assertRaises(exception.InstanceExists,
+                          db.instance_update,
+                          self.context,
+                          uuid2p1,
+                          values)
+
+        # With scope 'project' a duplicate in a different project should work:
+        self.flags(osapi_compute_unique_server_name_scope='project')
+        db.instance_update(otherprojectcontext, uuid1p2, values)
+
     def test_instance_update_with_and_get_original(self):
         ctxt = context.get_admin_context()