Add unique constraints to Cell.

In documentation: "name: Name of the current cell. This must be
unique for each cell"
Added unique constraint 'uniq_cell_name0deleted' ('name','deleted')
to Cell model and migrate sripts.
Added new exception `CellsExists`. Updated cell_create() in db.api.
Tests updated respectively.

blueprint db-enforce-unique-keys

Change-Id: Ib76e167089cb4756e4438613b49013ebf0874afe

2 files changed, 34 insertions, 0 deletions

diff --git a/nova/tests/db/test_db_api.py b/nova/tests/db/test_db_api.py
index df5561ae0..a1f37712f 100644
--- a/nova/tests/db/test_db_api.py
+++ b/nova/tests/db/test_db_api.py
@@ -4929,6 +4929,11 @@ class CellTestCase(test.TestCase, ModelsObjectComparatorMixin):
         self.assertRaises(exception.CellNotFound, db.cell_update, self.ctxt,
                           'cellnotinbase', self._get_cell_base_values())
 
+    def test_cell_create_exists(self):
+        db.cell_create(self.ctxt, self._get_cell_base_values())
+        self.assertRaises(exception.CellExists, db.cell_create,
+                          self.ctxt, self._get_cell_base_values())
+
 
 class ArchiveTestCase(test.TestCase):
 
diff --git a/nova/tests/db/test_migrations.py b/nova/tests/db/test_migrations.py
index dc77a27d7..812f0d8ae 100644
--- a/nova/tests/db/test_migrations.py
+++ b/nova/tests/db/test_migrations.py
@@ -1643,6 +1643,35 @@ class TestNovaMigrations(BaseMigrationTestCase, CommonTestsMixIn):
         rows = services.select().execute().fetchall()
         self.assertFalse('disabled_reason' in rows[0])
 
+    def _pre_upgrade_189(self, engine):
+        cells = db_utils.get_table(engine, 'cells')
+        data = [
+                {'name': 'name_123', 'deleted': 0},
+                {'name': 'name_123', 'deleted': 0},
+                {'name': 'name_345', 'deleted': 0},
+        ]
+        for item in data:
+            cells.insert().values(item).execute()
+        return data
+
+    def _check_189(self, engine, data):
+        cells = db_utils.get_table(engine, 'cells')
+
+        def get_(name, deleted):
+            deleted_value = 0 if not deleted else cells.c.id
+            return cells.select().\
+                   where(cells.c.name == name).\
+                   where(cells.c.deleted == deleted_value).\
+                   execute().\
+                   fetchall()
+
+        self.assertEqual(1, len(get_('name_123', False)))
+        self.assertEqual(1, len(get_('name_123', True)))
+        self.assertEqual(1, len(get_('name_345', False)))
+        self.assertRaises(sqlalchemy.exc.IntegrityError,
+                          cells.insert().execute,
+                          {'name': 'name_123', 'deleted': 0})
+
 
 class TestBaremetalMigrations(BaseMigrationTestCase, CommonTestsMixIn):
     """Test sqlalchemy-migrate migrations."""