Guard against empty rotation scheme

rotate_backups/__init__.py

@@ -11,7 +11,7 @@
 """
 
 # Semi-standard module versioning.
-__version__ = '2.0'
+__version__ = '2.1'
 
 # Standard library modules.
 import collections
@@ -129,7 +129,12 @@ def __init__(self, rotation_scheme, include_list=None, exclude_list=None, dry_ru
         :param io_scheduling_class: Use ``ionice`` to set the I/O scheduling class
                                     (expected to be one of the strings 'idle',
                                     'best-effort' or 'realtime').
+        :raises: :exc:`~exceptions.ValueError` when the rotation scheme
+                 dictionary is empty (this would cause all backups to be
+                 deleted).
         """
+        if not rotation_scheme:
+            raise ValueError("Refusing to use empty rotation scheme! (all backups would be deleted)")
         self.rotation_scheme = rotation_scheme
         self.include_list = include_list
         self.exclude_list = exclude_list

rotate_backups/tests.py

@@ -16,6 +16,7 @@
 import coloredlogs
 
 # The module we're testing.
+from rotate_backups import RotateBackups
 from rotate_backups.cli import main
 
 # Initialize a logger for this module.
@@ -86,7 +87,9 @@ def setUp(self):
         coloredlogs.install(level=logging.DEBUG)
 
     def test_argument_validation(self):
-        """Test argument validation of the ``ionice`` scheduling class."""
+        """Test argument validation."""
+        # Test that an empty rotation scheme raises an exception.
+        self.assertRaises(ValueError, RotateBackups, rotation_scheme={})
         # Test that an invalid ionice scheduling class causes an error to be reported.
         assert run_cli('--ionice=unsupported-class') != 0
         # Test that an invalid rotation scheme causes an error to be reported.