Fix volume backup import test

There is a bug in Cinder (#1455043) and backups are incorrectly imported
into the DB, and once that is fixed current tempest backup import/export
test will fail.

The reason for mentioned failure is that backup imports preserve
original backup id, so we cannot import a backup to a system where it
already exists, as is the case of our test.

This patch fixes this by importing the backup with a "fake" uuid so that
the import doesn't give an error.

Co-Authored-By: Yuriy Nesenenko <ynesenenko@mirantis.com>
Related-Bug: #1476416
Change-Id: I38e1a7b7d269278acd7963b990a263acd3d6e0d5
diff --git a/tempest/api/volume/admin/test_volumes_backup.py b/tempest/api/volume/admin/test_volumes_backup.py
index b09cd2c..1289297 100644
--- a/tempest/api/volume/admin/test_volumes_backup.py
+++ b/tempest/api/volume/admin/test_volumes_backup.py
@@ -13,11 +13,15 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+import base64
+import six
+
+from oslo_serialization import jsonutils as json
+
 from tempest.api.volume import base
 from tempest.common.utils import data_utils
 from tempest.common import waiters
 from tempest import config
-from tempest.lib import decorators
 from tempest import test
 
 CONF = config.CONF
@@ -41,6 +45,20 @@
         self.backups_adm_client.delete_backup(backup_id)
         self.backups_adm_client.wait_for_backup_deletion(backup_id)
 
+    def _decode_url(self, backup_url):
+        return json.loads(base64.decodestring(backup_url))
+
+    def _encode_backup(self, backup):
+        retval = json.dumps(backup)
+        if six.PY3:
+            retval = retval.encode('utf-8')
+        return base64.encodestring(retval)
+
+    def _modify_backup_url(self, backup_url, changes):
+        backup = self._decode_url(backup_url)
+        backup.update(changes)
+        return self._encode_backup(backup)
+
     @test.idempotent_id('a66eb488-8ee1-47d4-8e9f-575a095728c6')
     def test_volume_backup_create_get_detailed_list_restore_delete(self):
         # Create backup
@@ -78,9 +96,13 @@
         waiters.wait_for_volume_status(self.admin_volume_client,
                                        restore['volume_id'], 'available')
 
-    @decorators.skip_because(bug='1455043')
     @test.idempotent_id('a99c54a1-dd80-4724-8a13-13bf58d4068d')
     def test_volume_backup_export_import(self):
+        """Test backup export import functionality.
+
+        Cinder allows exporting DB backup information through its API so it can
+        be imported back in case of a DB loss.
+        """
         # Create backup
         backup_name = data_utils.rand_name('Backup')
         backup = (self.backups_adm_client.create_backup(
@@ -99,25 +121,40 @@
                         'cinder.backup.drivers'))
         self.assertIsNotNone(export_backup['backup_url'])
 
+        # NOTE(geguileo): Backups are imported with the same backup id
+        # (important for incremental backups among other things), so we cannot
+        # import the exported backup information as it is, because that Backup
+        # ID already exists.  So we'll fake the data by changing the backup id
+        # in the exported backup DB info we have retrieved before importing it
+        # back.
+        new_id = data_utils.rand_uuid()
+        new_url = self._modify_backup_url(
+            export_backup['backup_url'], {'id': new_id})
+
         # Import Backup
         import_backup = self.backups_adm_client.import_backup(
             backup_service=export_backup['backup_service'],
-            backup_url=export_backup['backup_url'])['backup']
-        self.addCleanup(self._delete_backup, import_backup['id'])
+            backup_url=new_url)['backup']
+
+        # NOTE(geguileo): We delete both backups, but only one of those
+        # deletions will delete data from the backup back-end because they
+        # were both pointing to the same backend data.
+        self.addCleanup(self._delete_backup, new_id)
         self.assertIn("id", import_backup)
+        self.assertEqual(new_id, import_backup['id'])
         self.backups_adm_client.wait_for_backup_status(import_backup['id'],
                                                        'available')
 
         # Verify Import Backup
         backups = self.backups_adm_client.list_backups(detail=True)['backups']
-        self.assertIn(import_backup['id'], [b['id'] for b in backups])
+        self.assertIn(new_id, [b['id'] for b in backups])
 
         # Restore backup
-        restore = (self.backups_adm_client.restore_backup(import_backup['id'])
-                   ['restore'])
+        restore = self.backups_adm_client.restore_backup(
+            backup['id'])['restore']
         self.addCleanup(self.admin_volume_client.delete_volume,
                         restore['volume_id'])
-        self.assertEqual(import_backup['id'], restore['backup_id'])
+        self.assertEqual(backup['id'], restore['backup_id'])
         waiters.wait_for_volume_status(self.admin_volume_client,
                                        restore['volume_id'], 'available')