tests: make linter happy

Make tests code pass linter rules.

Signed-off-by: Albert Esteve <aesteve@redhat.com>

backup/backup.py

@@ -18,12 +18,12 @@
 import ovirtsdk4 as sdk
 import ovirtsdk4.types as types
 
-import imagetransfer
+from . import imagetransfer
 
 log = logging.getLogger("backup")
 
 
-class Timeout:
+class Timeout(BaseException):
     """
     Raised when starting or stopping a backup times out.
     """
@@ -107,8 +107,8 @@ def download_backup(connection, backup, backup_dir, ca_file=None,
 
     for disk in backup_disks:
         incremental = disk.backup_mode == types.DiskBackupMode.INCREMENTAL
-        file_name = "{}.{}.{}.qcow2".format(
-            backup.to_checkpoint_id, disk.id, disk.backup_mode)
+        file_name = \
+            f"{backup.to_checkpoint_id}.{disk.id}.{disk.backup_mode}.qcow2"
         filename = os.path.join(backup_dir, file_name)
 
         if incremental:
@@ -238,8 +238,8 @@ def _get_backup(backup_service, backup_id):
     """
     try:
         backup = backup_service.get()
-    except sdk.NotFoundError:
-        raise RuntimeError(f"Backup {backup_id} does not exist")
+    except sdk.NotFoundError as exc:
+        raise RuntimeError(f"Backup {backup_id} does not exist") from exc
 
     if backup.phase == types.BackupPhase.FAILED:
         raise RuntimeError(f"Backup {backup_id} has failed")

backup/imagetransfer.py

@@ -56,15 +56,15 @@ def find_host(connection, sd_name):
     # Try to read this host hardware id.
 
     try:
-        with open("/etc/vdsm/vdsm.id") as f:
-            vdsm_id = f.readline().strip()
+        with open("/etc/vdsm/vdsm.id", encoding="utf-8") as file:
+            vdsm_id = file.readline().strip()
     except FileNotFoundError:
         log.debug("Not running on oVirt host, using any host")
         return None
-    except OSError as e:
+    except OSError as exc:
         # Unexpected error when running on ovirt host. Since choosing a host is
         # an optimization, log and continue.
-        log.warning("Cannot read /etc/vdsm/vdsm.id, using any host: %s", e)
+        log.warning("Cannot read /etc/vdsm/vdsm.id, using any host: %s", exc)
         return None
 
     log.debug("Found host hardware id: %s", vdsm_id)
@@ -73,13 +73,12 @@ def find_host(connection, sd_name):
 
     system_service = connection.system_service()
     data_centers = system_service.data_centers_service().list(
-        search='storage.name=%s' % sd_name,
+        search=f'storage.name={sd_name}',
         case_sensitive=True,
     )
     if len(data_centers) == 0:
         raise RuntimeError(
-            "Storage domain {} is not attached to a DC"
-            .format(sd_name))
+            f"Storage domain {sd_name} is not attached to a DC")
 
     data_center = data_centers[0]
     log.debug("Found data center: %s", data_center.name)
@@ -88,8 +87,8 @@ def find_host(connection, sd_name):
 
     hosts_service = system_service.hosts_service()
     hosts = hosts_service.list(
-        search="hw_id={} and datacenter={} and status=Up".format(
-            vdsm_id, data_center.name),
+        search=f"hw_id={vdsm_id} and "
+               f"datacenter={data_center.name} and status=Up",
         case_sensitive=True,
     )
     if len(hosts) == 0:
@@ -182,9 +181,9 @@ def create_transfer(
     while True:
         try:
             transfer = transfer_service.get()
-        except sdk.NotFoundError:
+        except sdk.NotFoundError as exc:
             # The system has removed the disk and the transfer.
-            raise RuntimeError(f"Transfer {transfer.id} was removed")
+            raise RuntimeError(f"Transfer {transfer.id} was removed") from exc
 
         if transfer.phase == types.ImageTransferPhase.FINISHED_FAILURE:
             # The system will remove the disk and the transfer soon.
@@ -281,7 +280,7 @@ def finalize_transfer(connection, transfer, disk, timeout=300):
         time.sleep(1)
         try:
             transfer = transfer_service.get()
-        except sdk.NotFoundError:
+        except sdk.NotFoundError as exc1:
             # Old engine (< 4.4.7): since the transfer was already deleted from
             # the database, we can assume that the disk status is already
             # updated, so we can check it only once.
@@ -290,16 +289,18 @@ def finalize_transfer(connection, transfer, disk, timeout=300):
                                 .disk_service(disk.id))
             try:
                 disk = disk_service.get()
-            except sdk.NotFoundError:
+            except sdk.NotFoundError as exc2:
                 # Disk verification failed and the system removed the disk.
                 raise RuntimeError(
-                    f"Transfer {transfer.id} failed: disk {disk.id} was removed")
+                    f"Transfer {transfer.id} failed: "
+                    f"disk {disk.id} was removed") from exc2
 
             if disk.status == types.DiskStatus.OK:
                 break
 
             raise RuntimeError(
-                f"Transfer {transfer.id} failed: disk {disk.id} status {disk.status}")
+                f"Transfer {transfer.id} failed: "
+                f"disk {disk.id} status {disk.status}") from exc1
 
         log.debug("Transfer %r in phase %r", transfer.id, transfer.phase)