add a --ref option to restore-backup

Author: perrette

papers/__main__.py

@@ -591,7 +591,10 @@ def restorecmd(parser, o, config):
     if not config.git:
         parser.print_help()
         raise PapersExit('only valid with --git enabled')
-    _restore_from_backupdir(config, restore_files=o.restore_files)
+    if o.ref:
+        _git_reset_to_commit(config, o.ref, restore_files=o.restore_files)
+    else:
+        _restore_from_backupdir(config, restore_files=o.restore_files)
 
 
 def gitcmd(parser, o, config):
@@ -1080,6 +1083,7 @@ def get_parser(config=None):
     undop = subparsers.add_parser('undo', parents=[cfg, _restorep, _stepsp], help='Undo changes on bibtex (if --git is not enabled, only back and forth with last modification). If --git-lfs is enabled, the file entry may differ if it does not exist on disk any more, unless --restore-files was passed.')
     redop = subparsers.add_parser('redo', parents=[cfg, _restorep, _stepsp], help='Redo changes on bibtex (if --git is not enabled, this has the same effect as papers undo)')
     restorep = subparsers.add_parser('restore-backup', parents=[cfg, _restorep], help='Restore bibtex from backup. Also restore files if --restore-files if passed (--git-lfs only).')
+    restorep.add_argument('--ref', help='Optional: restore specific commit (execute `papers git whatchanged` to obtain appropriate reference)')
 
     # git
     # ===

tests/test_undo.py

@@ -88,6 +88,15 @@ def test_undo(self):
         current = self.get_commit()
         self.assertEqual(current, commits[-1])
 
+        # Now go to specific commits
+        self.papers(f'restore-backup --ref {commits[0]}')
+        current = self.get_commit()
+        self.assertEqual(current, commits[0])
+
+        self.papers(f'restore-backup --ref {commits[-1]}')
+        current = self.get_commit()
+        self.assertEqual(current, commits[-1])
+
 
 class TestTimeTravelGitLocal(LocalGitInstallTest, TimeTravelBase):
     pass
@@ -115,6 +124,7 @@ def test_undo(self):
 
         self.assertMultiLineEqual(biblio.format(), biblio2.format())
 
+
 class TestUndoGitLocal(LocalGitLFSInstallTest):
 
     def test_undo(self):