Fix for the LVM hook erroring when the "--dry-run" flag is used (#1093).

NEWS

@@ -3,6 +3,7 @@
  * #1086: Fix for the "spot" check breaking when the "--progress" flag is used.
  * #1091: Fix for the "config generate" action generating invalid configuration when upgrading
    deprecated command hooks.
+ * #1093: Fix for the LVM hook erroring when the "--dry-run" flag is used.
  * Add support for Borg 2's "s3:" and "b2:" repository URLs, so you can backup to S3 or B2 cloud
    storage services even without using Rclone.
 

borgmatic/hooks/data_source/lvm.py

@@ -230,12 +230,13 @@ def dump_data_sources(
             )
 
         # Get the device path for the snapshot we just created.
-        try:
-            snapshot = get_snapshots(
-                hook_config.get('lvs_command', 'lvs'), snapshot_name=snapshot_name
-            )[0]
-        except IndexError:
-            raise ValueError(f'Cannot find LVM snapshot {snapshot_name}')
+        if not dry_run:
+            try:
+                snapshot = get_snapshots(
+                    hook_config.get('lvs_command', 'lvs'), snapshot_name=snapshot_name
+                )[0]
+            except IndexError:
+                raise ValueError(f'Cannot find LVM snapshot {snapshot_name}')
 
         # Mount the snapshot into a particular named temporary directory so that the snapshot ends
         # up in the Borg archive at the "original" logical volume mount point path.

tests/unit/hooks/data_source/test_lvm.py

@@ -556,16 +556,7 @@ def test_dump_data_sources_with_dry_run_skips_snapshots_and_does_not_touch_patte
     )
     flexmock(module.os).should_receive('getpid').and_return(1234)
     flexmock(module).should_receive('snapshot_logical_volume').never()
-    flexmock(module).should_receive('get_snapshots').with_args(
-        'lvs', snapshot_name='lvolume1_borgmatic-1234'
-    ).and_return(
-        (module.Snapshot(name='lvolume1_borgmatic-1234', device_path='/dev/lvolume1_snap'),)
-    )
-    flexmock(module).should_receive('get_snapshots').with_args(
-        'lvs', snapshot_name='lvolume2_borgmatic-1234'
-    ).and_return(
-        (module.Snapshot(name='lvolume2_borgmatic-1234', device_path='/dev/lvolume2_snap'),)
-    )
+    flexmock(module).should_receive('get_snapshots').never()
     flexmock(module).should_receive('mount_snapshot').never()
 
     assert (